Pollutants exhausts from automobiles
Automobiles used in our country are
a) Two wheelers and three wheelers, powered by two stroke petrol engines.
b) Passenger cars, powered by four stroke petrol engines.
c) Trucks and buses, powered by four stroke diesel engines.
The extent of pollution by these automobiles depends upon the enzine design, fuel consumption, operating condition. The emission from petrol engines are classified as follows:
A. Exhaust emissions
Theses are mostly comprised of CO, NOX, particulars containing lead compounds and unburned hydrocarbons. We can control the emission by the following ways
i. Modification of engine design
ii. Modification of operating conditions
iii. Treatment of exhaust gases.
iv. Modification of alternation of fuels.
B. Crank case emissions
It mostly contains hydrocarbons. The quality of blow depends on engine design, operating condition. This emission can be constituted by the following ways
i. By installing positive crank case ventilation system.
C. Evaporation emissions
It is estimated that an average evaporation emission of hydrocarbons from a passenger car is about 20 kg per year. Various methods to control evaporation emission are given below:
a. Stone the fuel vapour in crank case.
b. Modifying fuel by replacing C4 and C5 by corresponding paraffinic hydrocarbons.
c. Introducing suitable mechanical device.
Wednesday, August 24, 2011
Ozone (O3), Peroxy-acyl nitrile(PAN) and Photochemical smog
Ozone (O3), Peroxy-acyl nitrile(PAN) and Photochemical smog
Characteristics of Ozone (O3), Peroxy-acyl nitrile(PAN) and Photochemical smog
a) Pale blue gas.
b) Fairly water soluble, unstable and sweetish odour.
c) Very reactive oxidizing agent.
d) Capable of combining with many organic compounds in cells and tissues as well as rubber and other materials.
e) Ozone (O3) and Peroxy-acyl nitrile(PAN) are harmful to animals and humans.
Biochemical effects of Ozone (O3), Peroxy-acyl nitrile(PAN) and Photochemical smog
a) Oxidize cellular constituents.
b) Produce free radicals which are capable of producing toxic compounds.
c) Damage the DNA and reduce the genetic power.
d) Both Ozone (O3) and Photochemical smog causes eye irritation and respiratory tract.
e) Causing damage of lung capillaries.
f) Ozone may inhibit the activity of some enzyme involved in synthesis of cellulose and lipids in plants.
g) The Sulphur containing amino acid, example: Cystine are strongly attacked by PAN.
Characteristics of Ozone (O3), Peroxy-acyl nitrile(PAN) and Photochemical smog
a) Pale blue gas.
b) Fairly water soluble, unstable and sweetish odour.
c) Very reactive oxidizing agent.
d) Capable of combining with many organic compounds in cells and tissues as well as rubber and other materials.
e) Ozone (O3) and Peroxy-acyl nitrile(PAN) are harmful to animals and humans.
Biochemical effects of Ozone (O3), Peroxy-acyl nitrile(PAN) and Photochemical smog
a) Oxidize cellular constituents.
b) Produce free radicals which are capable of producing toxic compounds.
c) Damage the DNA and reduce the genetic power.
d) Both Ozone (O3) and Photochemical smog causes eye irritation and respiratory tract.
e) Causing damage of lung capillaries.
f) Ozone may inhibit the activity of some enzyme involved in synthesis of cellulose and lipids in plants.
g) The Sulphur containing amino acid, example: Cystine are strongly attacked by PAN.
Oxides of Sulphur
Oxides of Sulphur ( SOX)
Sources of Oxides of Sulphur ( SOX)
a) Combustion of coal
b) Combustion of petroleum products.
c) Burning of refuse
d) Oil refining
e) From power house
f) Sulphuric acid plant
g) Metallurgical operation.
h) Domestic burning of fuel.
Characterisrics of Oxides of Sulphur ( SOX)
a) Comprises of SO2 is 97 to 99 % and SO3 is 3 to 1 %.
b) SO2 is colourless, heavy, water soluble gas with pungent smell and irritating odour.
c) SO2 is rapidly diffusing, acid forming, oxidizing agent.
d) React with water forming H2SO3 and H2SO4 both of which can react with organic matter, metals and other materials.
Biochemical effects of Oxides of Sulphur ( SOX)
a) Absorbs quickly and irritates the upper respiratory tract.
b) Reacts with cellular constituent, example is enzyme.
c) The sulphuric acid forms lowers pH, which impairs enzymatic funtions and destroys various functional molecules.
d) Lung clearance and impaired pulmonary function are occurred.
Control of Oxides of Sulphur ( SOX)
a) Absorb SO2 is from the air.
b) Separate Sulphur from fuel.
c) Minimize the use of Sulphur fuel.
d) Use of natural gas instead of Sulphur fuel.
Sources of Oxides of Sulphur ( SOX)
a) Combustion of coal
b) Combustion of petroleum products.
c) Burning of refuse
d) Oil refining
e) From power house
f) Sulphuric acid plant
g) Metallurgical operation.
h) Domestic burning of fuel.
Characterisrics of Oxides of Sulphur ( SOX)
a) Comprises of SO2 is 97 to 99 % and SO3 is 3 to 1 %.
b) SO2 is colourless, heavy, water soluble gas with pungent smell and irritating odour.
c) SO2 is rapidly diffusing, acid forming, oxidizing agent.
d) React with water forming H2SO3 and H2SO4 both of which can react with organic matter, metals and other materials.
Biochemical effects of Oxides of Sulphur ( SOX)
a) Absorbs quickly and irritates the upper respiratory tract.
b) Reacts with cellular constituent, example is enzyme.
c) The sulphuric acid forms lowers pH, which impairs enzymatic funtions and destroys various functional molecules.
d) Lung clearance and impaired pulmonary function are occurred.
Control of Oxides of Sulphur ( SOX)
a) Absorb SO2 is from the air.
b) Separate Sulphur from fuel.
c) Minimize the use of Sulphur fuel.
d) Use of natural gas instead of Sulphur fuel.
Oxides of Nitrogen
Oxides of Nitrogen (NOX)
Sources
a) Automobile exhausts
b) Coal fire, gas fire furnace
c) Various boiler, power plant
d) Explosive industry
e) Fertilizer industry
f) Manufacturer of nitric acid
g) Firing of refuse
Characteristics of Oxides of Nitrogen
a) It comprises of NO, NO2, N2O
b) NO is colorless gas, slightly soluble in water.
c) NO2 is radish brown
d) N2O is soluble in water
e) NO2 is a oxidizing agent and form nitric acid by reaction in water.
f) Capable of reaction with all metal or organic compounds.
g) Involve in formation of ozone in atmosphere.
Biochemical effects of Oxides of Nitrogen
a) It can oxidize cellular lipids.
b) They can form bonds with hemoglobin.
c) They can reduce the efficiency of oxygen transport.
d) They can reduce destroy the catalytic power of enzyme.
e) No may be bonded with hemoglobin and form additional compound which is harmful for the body.
Effects of Oxides of Nitrogen on plants
a) Higher concentration of NO2 may be cause of damage of the leaves of plants.
b) May damage the tissue of the plants.
c) NO2 is highly destructive to plant and damage the vegetation power.
Control of Oxides of Nitrogen
a) Moderate a system to absorb the automobile exhausts.
b) Lowering the temperature in fertilizer industry.
c) Catalytic decomposition.
d) Reaction between NO and NO2.
e) Control of unwanted firing.
Sources
a) Automobile exhausts
b) Coal fire, gas fire furnace
c) Various boiler, power plant
d) Explosive industry
e) Fertilizer industry
f) Manufacturer of nitric acid
g) Firing of refuse
Characteristics of Oxides of Nitrogen
a) It comprises of NO, NO2, N2O
b) NO is colorless gas, slightly soluble in water.
c) NO2 is radish brown
d) N2O is soluble in water
e) NO2 is a oxidizing agent and form nitric acid by reaction in water.
f) Capable of reaction with all metal or organic compounds.
g) Involve in formation of ozone in atmosphere.
Biochemical effects of Oxides of Nitrogen
a) It can oxidize cellular lipids.
b) They can form bonds with hemoglobin.
c) They can reduce the efficiency of oxygen transport.
d) They can reduce destroy the catalytic power of enzyme.
e) No may be bonded with hemoglobin and form additional compound which is harmful for the body.
Effects of Oxides of Nitrogen on plants
a) Higher concentration of NO2 may be cause of damage of the leaves of plants.
b) May damage the tissue of the plants.
c) NO2 is highly destructive to plant and damage the vegetation power.
Control of Oxides of Nitrogen
a) Moderate a system to absorb the automobile exhausts.
b) Lowering the temperature in fertilizer industry.
c) Catalytic decomposition.
d) Reaction between NO and NO2.
e) Control of unwanted firing.
Friday, August 19, 2011
Air Pollution and Air Pollutants
Air Pollution
Air Pollution may be defined as the presence in the outer atmosphere of one or more contaminants or pollutants or combination of those substances in such quantities and of such duration as may be or may tend to be injuries to human, plant or animal life or property.
Classification of air pollutants
The air pollutants may be classified in different ways as follows
1. According to Origin
a) Primary pollutants: Directly emitted into the atmosphere. Example: CO, NO2, SO2 and hydrocarbons.
b) Secondary pollutants : divided from the primary pollutants due to chemical or photo-chemical reaction. Example: Ozone, PAN (0peroxy acyl nitrate), Photochemical smog.
2. According to chemical composition:
a) Organic pollutants: Example: Hydrocarbons, aldehydes, ketones, amines, alcohols.
b) Inorganic pollutants: Example: Carbon compounds( CO and Carbonates), Nitrogen Compounds(NOX, NH3), Halogen Compounds( HF, HCl), Oxidising agents( O3)
3. According to state of matter:
a) Gaseous pollutants: Get mixed with the air and do not settle out. Example: CO, NOX, SO2.
b) Particulate pollutants: Comprise of finely divided solids or liquids and often exist in colloid state as aerosols. Example: Smoke, fumes, dust, mist, fog.
Air Pollution may be defined as the presence in the outer atmosphere of one or more contaminants or pollutants or combination of those substances in such quantities and of such duration as may be or may tend to be injuries to human, plant or animal life or property.
Classification of air pollutants
The air pollutants may be classified in different ways as follows
1. According to Origin
a) Primary pollutants: Directly emitted into the atmosphere. Example: CO, NO2, SO2 and hydrocarbons.
b) Secondary pollutants : divided from the primary pollutants due to chemical or photo-chemical reaction. Example: Ozone, PAN (0peroxy acyl nitrate), Photochemical smog.
2. According to chemical composition:
a) Organic pollutants: Example: Hydrocarbons, aldehydes, ketones, amines, alcohols.
b) Inorganic pollutants: Example: Carbon compounds( CO and Carbonates), Nitrogen Compounds(NOX, NH3), Halogen Compounds( HF, HCl), Oxidising agents( O3)
3. According to state of matter:
a) Gaseous pollutants: Get mixed with the air and do not settle out. Example: CO, NOX, SO2.
b) Particulate pollutants: Comprise of finely divided solids or liquids and often exist in colloid state as aerosols. Example: Smoke, fumes, dust, mist, fog.
Carcinogen, Pesticides and Bio-warfare Agent
Carcinogen
The term carcinogen means a group of chemicals which cause cancer in animal and human. The carcinogens affect DNA, preventing it from giving the necessary direction for the synthesis of substances which control the cell growth.
Carcinogens to which workers should not be exposed. Some compounds:
1. 4-nitro phenyl
Uses: Chemical analysis
Hazards: may cause blader cancer.
2. α-napthyl amine
Uses:Antioxident, dye manufacturing, colour, film manufacter
Hazards: may cause blader cancer.
3. β –napthyl amine
Uses: dye manufacturing, reagent.
Hazards: May cause bladder cancer.
4. benzidine
Uses: manufactur of Dye, Rubber, plstic
Hazards:it may cause bladder.
5. 3,3 dichlorobenzidine:
Uses: dye manufacturer
Hazards: known carcinogen
6. veinyl chloride:
Uses: PVC manufacture
Hazards: liver cancer
7. ethylene dichloride :
Uses: industrial solvent, gasoline additive
Hazards: lung cancer
Biochemical Effects of Pesticides
Biochemical processes constitute the major mechanism by which pesticides in the environment are degraded and detoxified.
Among the pesticides, the biological action of DDT on the environment has been most extensively studied. The central nervous system is the target of DDT, like many other insecticides. DDT dissolves in lipid (fat) tissue and accumulates in the fatty membrane surrounding nerve cells. The net result is disruption of the central nervous system killing the target insect.
While DDT is fairly insoluble and persist in the environment, the other groups organophosphates and carbamates degrades quite rapidly in the environment. The later react with oxygen (O2) and water (H2O) undergoes decomposition within a few days in the environment.
DDT accumulates in the food chain as
Plankton (0.04 ppm DDT) >> Fish (0.17 to o.27 DDT) >> Fish eating birds (3.1 to 75.5 ppm)
Fish (0.17 to o.27 DDT) >> Clams 0.42 ppm DDT >> Plankton (0.04 ppm DDT)
Bio-warfare Agent
The bio-warfare agent which are harmful to human being are called bio-warfare agent.
1. Anthrax
Definition: bacteria in spore form not contagious
Attack: inhalation, ingestion, skin abrasion
Symptoms: flue like symptoms lead to breathing problem
Treatment: treatment by antibiotics or pre-vaccine
2. Plague
Definition: agent is rodents, contagious
Attack: through aerosol cans
Symptoms: fever, headaches and weakness
Duration of Death: 2-4 days
Treatment: Treatment by antibiotics
3. Small pox
Definition: it is deadly and highly contigious
Attack: through aerosol cans
Symptoms: fever, fatigue and body aches
Duration of Death: first 2 weeks.
Treatment: vaccine
4. Chlorine
Definition: green yellow pungent smelling gas
The term carcinogen means a group of chemicals which cause cancer in animal and human. The carcinogens affect DNA, preventing it from giving the necessary direction for the synthesis of substances which control the cell growth.
Carcinogens to which workers should not be exposed. Some compounds:
1. 4-nitro phenyl
Uses: Chemical analysis
Hazards: may cause blader cancer.
2. α-napthyl amine
Uses:Antioxident, dye manufacturing, colour, film manufacter
Hazards: may cause blader cancer.
3. β –napthyl amine
Uses: dye manufacturing, reagent.
Hazards: May cause bladder cancer.
4. benzidine
Uses: manufactur of Dye, Rubber, plstic
Hazards:it may cause bladder.
5. 3,3 dichlorobenzidine:
Uses: dye manufacturer
Hazards: known carcinogen
6. veinyl chloride:
Uses: PVC manufacture
Hazards: liver cancer
7. ethylene dichloride :
Uses: industrial solvent, gasoline additive
Hazards: lung cancer
Biochemical Effects of Pesticides
Biochemical processes constitute the major mechanism by which pesticides in the environment are degraded and detoxified.
Among the pesticides, the biological action of DDT on the environment has been most extensively studied. The central nervous system is the target of DDT, like many other insecticides. DDT dissolves in lipid (fat) tissue and accumulates in the fatty membrane surrounding nerve cells. The net result is disruption of the central nervous system killing the target insect.
While DDT is fairly insoluble and persist in the environment, the other groups organophosphates and carbamates degrades quite rapidly in the environment. The later react with oxygen (O2) and water (H2O) undergoes decomposition within a few days in the environment.
DDT accumulates in the food chain as
Plankton (0.04 ppm DDT) >> Fish (0.17 to o.27 DDT) >> Fish eating birds (3.1 to 75.5 ppm)
Fish (0.17 to o.27 DDT) >> Clams 0.42 ppm DDT >> Plankton (0.04 ppm DDT)
Bio-warfare Agent
The bio-warfare agent which are harmful to human being are called bio-warfare agent.
1. Anthrax
Definition: bacteria in spore form not contagious
Attack: inhalation, ingestion, skin abrasion
Symptoms: flue like symptoms lead to breathing problem
Treatment: treatment by antibiotics or pre-vaccine
2. Plague
Definition: agent is rodents, contagious
Attack: through aerosol cans
Symptoms: fever, headaches and weakness
Duration of Death: 2-4 days
Treatment: Treatment by antibiotics
3. Small pox
Definition: it is deadly and highly contigious
Attack: through aerosol cans
Symptoms: fever, fatigue and body aches
Duration of Death: first 2 weeks.
Treatment: vaccine
4. Chlorine
Definition: green yellow pungent smelling gas
Wednesday, August 17, 2011
Toxicity of Mercury and Cyanide
Sources and Toxicity of Mercury (Hg)
Sources: Industrial mining, waste, pesticides, coal etc.
The Toxicity of Mercury depends on its chemical species as shown below
1) Properties of Mercury (Hg)
o Elemental Hg is fairly inert and non-toxic.
o Vapour highly toxic when inhailed
o If swallowed, it excreted without serious damage.
2) Mercuous ion(Hg2+)
o Insoluble as chloride
o Low toxicity
3) Mercuric ion(Hg3+)
o Toxic but not across biological membrane
o It attacks the sulphur containing amino acid of protein.
4) Organomercurials
o Highly toxic
o Partially causes irreversible nerve and brain damage.
o Easily transported to the biological membrane.
o Stored in flat tissue.
5) Diorganomercurials
o Low toxic
o Can be converted into Organomercurials.
6) Mercuric Sulphide (HgS): highly insoluble and non-toxic.
Biochemical effects of Cyanides
Cyanides occurs in seeds of fruits such as apples, apricots, cherries, peaches and plums. Cyanide in the plant is bonded to glycoside(sugar) called amygdalin and is released by enzymatic or acidic hydrolysis. Cyanide enters the environment from many sources. HCN is employed as a fumigating agent to destroy rodents in grain bins, building in electroplating and metal cleaning industry.
Cyanide exerts its toxic action by inhibiting oxidative enzymes from mediating the process by which oxygen is utilized to complete the production of ATP n the mitochondria
In the first step cyanide bind to ferricoytochrome oxydase. The important products are the ATP
Step 1: Fe (3)-oxide + glucose >> Fe (2)-oxide
Step 2: Fe (2)-oxide + 2H+ + 1/2O2 >> Fe(3) + H2O + ADP/ATP
Cyanide interferes with step 1 above by forming a bond with Fe(3)-oxide, which is thereby inactivated so that the reaction in step 2, the energy producing process is prevented.
Biochemical Effects of Arsenic, Cadmium and Lead
Biochemical Effects of Arsenic
Arsenic commonly occur in insecticides , fungicides and herbicides. Arsenic exerts its toxic action by attacking SH groups of an enzyme, thereby inhibiting action
SH(Enzyme)SH + O2As(O) >> S (Enzyme)S-As-O + 2OH-
The enzymes which generate cellular energy in the citric acid cycle are adversely affected. The inhibitory action is based on inactivation of pyruvate dehydrogenase by complexation with As, were by generation of ATP is prevented.
A more important step is ATP generation is the enzymatic synthesis of 1,3 diphosphoglycerate from glyceraldehyde 3-phosphate . Arsenic interacts by producing 1-arseno-3-phosphoglycerate instead of 1, 3 diphosphoglycerate.
Biochemical Effects of Cadmium
Cadmium occurs in nature in association of zinc minerals. The biochemical effects of cadmium are
a) At high levels cadmium causes kidney problems, aneamia and bone mammrow disorder.
b) The major portion of cadmium ingested our body is trapped in the kidneys and eliminated
c) Small portion is bound most effectively by the body protein, present in the kidney and rest is stored in the body.
d) When the excessive amount cadmium ion are ingested, it replaces zinc ion at the key enzymatic sites, causing metabolic disorder.
e) High level of cadmium ion causes renal dysfunction, hypertension and cancer.
Biochemical Effects of Lead
Lead is a relative abundant of metal in nature occurring in lead minerals.
a) The major biochemical effect of lead is that its interference with heme-synthesis, which lead to hematological damage. Pb inhibit the several of key enzyme involved in the overall process of heme-synthesis whereby the metabolic intermediate accumulate.
b) The overall effect is the disruption of the synthesis of hemoglobin.
c) Pb does not permit the utilization of O2 and glucose for life sustanency energy production.
d) Higher level of Pb causes anaemia.
e) Elevated Pb levels in blood causes kidney dysfunction.
f) Elevated Pb levels in blood causes brain damage.
Tuesday, August 16, 2011
Classification of Toxic Chemicals
Classification of Toxic Chemicals
Toxic chemicals may be classified according to their function and effects. According to the “international resister of potentially toxic chemical” of the United Nations environment programme, there are four million known chemicals in the world today and another 30000 new compound are added to the list every year. Among these 60000 to 70000 chemicals are commodity used.
According to environment on which it present toxic chemicals are divided into two class:
1. Toxic chemicals in Air
2. Toxic chemicals in water.
1. Toxic chemicals in Air
About 24 extremely hazardous substances in the atmosphere. These are given below:
a) Acrylonitrile
b) As
c) Asbestos
d) Benzene
e) Be
f) Cd
g) Chlorinated solvent
h) CFC
i) Chromates
j) Coke oven emission
k) Diethyl stillbesterol
l) Dibromomonochloropropane
m) Ethylene dibromate
n) Ethylene oxide
o) Pb
p) Hg
q) Nitrosoamine
r) Ozone
s) Polybromominated biphenyl
t) Polychlorinated biphenyl
u) Radiation
v) Sulpher Dioxide
w) Vinyl chloride
x) Toxic waste.
2. Toxic chemicals in water.
A. Arsenic
Sources: mining by-product, pesticides, chem. Waste, etc.
Effects: Toxic, possibly carcinogenic, etc.
B. Cadmium
Sources: Industrial discharge, mining waste, metal plating, water pipes, etc.
Effects: Replaces Zn biochemical, causes high blood pressure, kidney damage, destruction of testicular tissue and red blood cell, toxicology to aquatic bio, etc.
C. Boron
Sources: Coal, Detergent formation, industrial waste, etc.
Effects: toxic to plants, etc.
D. Chromium
Sources: Metal plating, cooling tower, water additives, normally found as chromium polluted water, etc.
Effects: essential trace element, possibly carcinogenic, etc.
E. Copper
Sources: metal plating, industrial and domestic waste, mining, mineral leaching, etc.
Effects: Essential trace element not very toxic to animals, toxic to plant and algae at moderate levels, etc.
F. Fluorine
Sources: Natural geological sources, industrial waste and water additives, etc.
Effects: Prevent tooth decay about 1 mg/l.
G. Lead
Sources: Industry, mining, plumbing, coal, gasoline, etc.
Effects: Toxic, wild-life destroyed, etc.
H. Manganese
Sources: mining, industrial wastes, acid mine drainage, microbial action on manganese minerals at low potential, etc.
Effects: relatively non-toxic to animal, toxic to plant at higher level, stains material, etc.
I. Mercury
Sources: Industrial waste, mining, pesticide, coal, etc.
Effects: highly toxic, etc.
J. Molybdenum
Sources: industrial waste, industrial sources, etc.
Effects: possibly toxic to animal, essential to plant, etc.
K. Selenium
Sources: Natural geological sources, sulphur, coal, etc.
Effects: essential at low level and toxic at high level, etc.
L. Zinc
Sources: Industrial waste, metal plating, plumbing, etc.
Effects: Essential in many metallo-enzyme toxic to plant at higher level, etc.
M. Beryllium
Sources: Coal, nuclear power and space industry, etc.
Effects: Acute and chrome toxicity, possibly carcinogenic, etc.
Toxic Chemicals and its Effect on Enzeme
Toxic Chemicals
There are number of chemicals in the environment. Some of these are toxic and rest are non-toxic. The toxic chemicals are discharged by industries into air, water and soil. They get into human food chain from the environment. Once they enter our biological system, they disturb our biological processes leading in some caases to fatal diseases. Chemical toxicology is a branch of the modern technology for study of toxic chemicals and mode of action.
Schwardz used the term “concentration window” to draw the arbitrary lines of demarcation.
a) Essential at trace level for substance of trace level.
b) Deficient at lower than (a) causing metabolic disorder.
c) Toxic at higher than (a) causing adverse effect.
The effects of Toxic Chemicals on Enzyme
In general toxic chemicals attack the active sites of enzymes inhibiting essential enzyme function. Heavy metal atom e.g., Hg2+, Pb2+, Cd2+ act as a effective enzyme inhibitors. They have affinity for sulphur containing ligands e.g., SCH3 and –SH in methionic and cystonic amino acid which are the part of enzyme structure.
SH(Enzyme)SH + Hg2+ >>> S (Enzyme)SHg + 2H+
Metalloenzymes contain metals in their structures. Their action is inhibited when one metal ion of metallo-enzymes is replaced by another metal ion of similar size and charge.
As for example, Zn2+ in some metallo-enzymes is substituted by Cd+2 which leads to cadmium toxiacity. The enzyme inhibited by Cd2+ include alcohol dehydrogenase amylase, peptidase.
Monday, August 8, 2011
Fertilizer industry waste water treatment
Fertilizer industry waste water treatment
Sources:
Spill overs from manufactured of acids used as raw materials, spill over of the final fertilizer products, boiler blow down, cooling waters etc.
Properties
i. Effluent from ammonia production is highly alkaline.
ii. Effluent from phosphoric acid manufacturer is acidic.
iii. High amount of fluoride present in the phophatic fertilizer.
Bad Effects
i. Fertilizer effluents cause eutrophication due to algal bloom.
ii. Enrich the fluoride content of receiving waters causing dental skeletal fluorosis to human.
iii. Presence of Cr, CN-, NH3 are harmful to aquatic life.
iv. Abnormal calcification of bones in animals.
How to Treatment those
a) Segregation of wastes.
b) Removal of urea by hydrolysis.
c) Removal of fluoride and phosphate by precipating with chalk.
d) Removal of oil and greases by mechanical oil separation.
Sources:
Spill overs from manufactured of acids used as raw materials, spill over of the final fertilizer products, boiler blow down, cooling waters etc.
Properties
i. Effluent from ammonia production is highly alkaline.
ii. Effluent from phosphoric acid manufacturer is acidic.
iii. High amount of fluoride present in the phophatic fertilizer.
Bad Effects
i. Fertilizer effluents cause eutrophication due to algal bloom.
ii. Enrich the fluoride content of receiving waters causing dental skeletal fluorosis to human.
iii. Presence of Cr, CN-, NH3 are harmful to aquatic life.
iv. Abnormal calcification of bones in animals.
How to Treatment those
a) Segregation of wastes.
b) Removal of urea by hydrolysis.
c) Removal of fluoride and phosphate by precipating with chalk.
d) Removal of oil and greases by mechanical oil separation.
Waste water treatment of Leather Tanning Industries
Waste water treatment of Leather Tanning Industries
Sources:
Beam house washing, processing, soaking, tanning, liming, dehairing, deflushing, deliming, bating, picking, dyeing are the main source of waste water.
Characteristics
i. It contain excess NaCl.
ii. It has bad-odour.
iii. It has dark color.
iv. It has a high BOD value.
v. It has a high COD value.
vi. It contain suspended solids.
Bad Effects
i. The constituents of tannery effluent are deleterious and irrerespective.
ii. It imparts persistent dull brown to the receiving water.
iii. Highly repulsive odour is imparted to the receiving water.
iv. The acidic or alkaline effluent are corrosive to concrete and metal pipe.
v. Excess NaCl is corrosive.
vi. The effluent may be contain pathogenic bacteria..
vii. Dissolved Cr is harmful for fish.
viii. It has nonclear water.
How to Treatment those
i. Primary treatment includes screening to remove hairs, fleshing, fats etc.
ii. Secondary treatment includes processes such as chemicals coagulation and biological treatment.
iii. Removal of chromium followed by activated sludge process.
Sources:
Beam house washing, processing, soaking, tanning, liming, dehairing, deflushing, deliming, bating, picking, dyeing are the main source of waste water.
Characteristics
i. It contain excess NaCl.
ii. It has bad-odour.
iii. It has dark color.
iv. It has a high BOD value.
v. It has a high COD value.
vi. It contain suspended solids.
Bad Effects
i. The constituents of tannery effluent are deleterious and irrerespective.
ii. It imparts persistent dull brown to the receiving water.
iii. Highly repulsive odour is imparted to the receiving water.
iv. The acidic or alkaline effluent are corrosive to concrete and metal pipe.
v. Excess NaCl is corrosive.
vi. The effluent may be contain pathogenic bacteria..
vii. Dissolved Cr is harmful for fish.
viii. It has nonclear water.
How to Treatment those
i. Primary treatment includes screening to remove hairs, fleshing, fats etc.
ii. Secondary treatment includes processes such as chemicals coagulation and biological treatment.
iii. Removal of chromium followed by activated sludge process.
Waste water treatment from Electroplating Industries
Waste water treatment from Electroplating Industries
Sources: surface cleaning, pickling, stripping, electroplating, contribute alkali waste containg NaOH, carbonates, silicates wetting, greases and organic emulsifiers. Electroplating bath contains Cu, Ni, Ag, Zn, Cd, Cr, Sn, Pb, Fe etc.
Characteristics
i. The waste water contain some solvent such as trilene, benzene, petrol, aldehyde etc.
ii. It contain unused acids.
iii. It contains oil, greases as contaminant.
iv. It contain biodegradable solids.
v. It contain suspended solids.
vi. It has bad odour.
Bad Effects
i. Plating effeluent are highly toxic and corrosive.
ii. The toxicity of chemicals to microorgsnisms inhibits self purification properly of the stream.
iii. Fe, Sn etc. impart colour to the receiving stream.
iv. Phosphates and nitrates present in the effluent help in excessive algal growth.
v. Colloidal and suspended impurities impart unaesthetic appearance to the stream.
How to Treatment those
i. Segregation of cyanide wastes, chromium, wastes and other toxic metals bearing wastes.
ii. Treatment of cyanide waste by alkaline chlorination.
iii. Treatment of chromium bearing effluent.
iv. After the treatment of cyanide and chromium waste setting down the precipitation. Then the sludge may be dried on sand and disposed in landfills.
v. Scraping of the floating oils and greases from holding task.
vi. The rinse water may be reused after removing the ionic impurities.
Sources: surface cleaning, pickling, stripping, electroplating, contribute alkali waste containg NaOH, carbonates, silicates wetting, greases and organic emulsifiers. Electroplating bath contains Cu, Ni, Ag, Zn, Cd, Cr, Sn, Pb, Fe etc.
Characteristics
i. The waste water contain some solvent such as trilene, benzene, petrol, aldehyde etc.
ii. It contain unused acids.
iii. It contains oil, greases as contaminant.
iv. It contain biodegradable solids.
v. It contain suspended solids.
vi. It has bad odour.
Bad Effects
i. Plating effeluent are highly toxic and corrosive.
ii. The toxicity of chemicals to microorgsnisms inhibits self purification properly of the stream.
iii. Fe, Sn etc. impart colour to the receiving stream.
iv. Phosphates and nitrates present in the effluent help in excessive algal growth.
v. Colloidal and suspended impurities impart unaesthetic appearance to the stream.
How to Treatment those
i. Segregation of cyanide wastes, chromium, wastes and other toxic metals bearing wastes.
ii. Treatment of cyanide waste by alkaline chlorination.
iii. Treatment of chromium bearing effluent.
iv. After the treatment of cyanide and chromium waste setting down the precipitation. Then the sludge may be dried on sand and disposed in landfills.
v. Scraping of the floating oils and greases from holding task.
vi. The rinse water may be reused after removing the ionic impurities.
Saturday, August 6, 2011
Waste water treatment from Pulp and Paper Industries
Waste water treatment from Pulp and Paper Industries
Sources
The raw material preparation, pulping, washing, bleaching, chemical recovery, screening of pulp and paper making contribute to wash effluents.
Characteristics
i. The water is dark brown.
ii. It contain high percent of suspended solid.
iii. It contain high percent of dissolved solid.
iv. It has bad odour.
v. It has high COD.
vi. Resistant to biological oxidation.
Effects
i. The dark vlour imparts persistent colour to the receiving water stream and inhibits photosynthesis.
ii. The immediate oxygen demand of the effluent brings about depletion of oxygen of the receiving stream.
iii. The chemical present in the effluent are harmful to fauna and flora of the receiving water.
Treatment option
i. Recovery of bi-products.
ii. Preliminary and primary operation carried out to remove suspended matter.
iii. Chemical treatment to remove dissolved organics.
iv. Lagoonong for storage and biodegradation of organic matter.
Sources
The raw material preparation, pulping, washing, bleaching, chemical recovery, screening of pulp and paper making contribute to wash effluents.
Characteristics
i. The water is dark brown.
ii. It contain high percent of suspended solid.
iii. It contain high percent of dissolved solid.
iv. It has bad odour.
v. It has high COD.
vi. Resistant to biological oxidation.
Effects
i. The dark vlour imparts persistent colour to the receiving water stream and inhibits photosynthesis.
ii. The immediate oxygen demand of the effluent brings about depletion of oxygen of the receiving stream.
iii. The chemical present in the effluent are harmful to fauna and flora of the receiving water.
Treatment option
i. Recovery of bi-products.
ii. Preliminary and primary operation carried out to remove suspended matter.
iii. Chemical treatment to remove dissolved organics.
iv. Lagoonong for storage and biodegradation of organic matter.
Waste water treatment from Textile Industries
Textile Industry
Sources:
i. Cotton textile industry: Various operations involved in a cotton textile mill are combing, spinning, sizing, weaving and knitting are the main source of waste water.
ii. Synthetic textile industry: The operations like scouring, dyeing, rinsing, bleaching and finishing are the source of waste water.
iii. Wool industry: Various operations involved in a cotton textile mill are combing, spinning, sizing, weaving and knitting are the main source of waste water in wool industryalso.
Characteristics
i. The waste water generally coloured.
ii. It contain starch, polyvinyl alcohol and softners.
iii. It has a high BOD and high dissolved minerals.
iv. It contains suspended solids.
v. It contains soap-alkaly etec.
Effects
i. The dyes present impart persistent colour to the receiving sterams and interfere with photosynthesis of phytoplankton.
ii. The high pH is deleterious to aquatic life.
iii. The colloidal and suspended impurities causes turbidity in the receiving waters.
iv. The oil present interferes with the oxygenation of the receiving water stream.
v. The dissolved minerals increase salinity of the water.
vi. The toxic chemicals destroys fish and other microbial organism.
vii. It depletes the dissolved oxygen.
viii. The dissolved solid form incrustations on the surface of the surface of the sewers.
ix. The dissolved impurities cause corrosion in the metallic parts.
Treatment options
i. Segregation of wasters.
ii. Screening to remove coarse suspended matter.
iii. Removal of grease by equalization, neutralization.
iv. Chemical coagulation to remove colour, suspended and colloidal impurities.
v. Aerobic biological treatment.
vi. Finally tertiary treatment to remove dissolved solid.
Sources:
i. Cotton textile industry: Various operations involved in a cotton textile mill are combing, spinning, sizing, weaving and knitting are the main source of waste water.
ii. Synthetic textile industry: The operations like scouring, dyeing, rinsing, bleaching and finishing are the source of waste water.
iii. Wool industry: Various operations involved in a cotton textile mill are combing, spinning, sizing, weaving and knitting are the main source of waste water in wool industryalso.
Characteristics
i. The waste water generally coloured.
ii. It contain starch, polyvinyl alcohol and softners.
iii. It has a high BOD and high dissolved minerals.
iv. It contains suspended solids.
v. It contains soap-alkaly etec.
Effects
i. The dyes present impart persistent colour to the receiving sterams and interfere with photosynthesis of phytoplankton.
ii. The high pH is deleterious to aquatic life.
iii. The colloidal and suspended impurities causes turbidity in the receiving waters.
iv. The oil present interferes with the oxygenation of the receiving water stream.
v. The dissolved minerals increase salinity of the water.
vi. The toxic chemicals destroys fish and other microbial organism.
vii. It depletes the dissolved oxygen.
viii. The dissolved solid form incrustations on the surface of the surface of the sewers.
ix. The dissolved impurities cause corrosion in the metallic parts.
Treatment options
i. Segregation of wasters.
ii. Screening to remove coarse suspended matter.
iii. Removal of grease by equalization, neutralization.
iv. Chemical coagulation to remove colour, suspended and colloidal impurities.
v. Aerobic biological treatment.
vi. Finally tertiary treatment to remove dissolved solid.
Water Treatment
Water Treatment
The various methods used in sewage and industrial waste water treatment are as follows-
1. Preliminary treatment : The principle objectives of preliminary treatment are the removal of gross solid, i.e., large floating and suspended solid matters, girt, oil and grease if they present in considerable quantities.
2. Primary treatment: After removal of gross solids, gritty materials and excessive quantities of oil and grease, the next step is to remove the remaining suspended solids as much as possible. The step is aimed at reducing the strength of the waste water and also to facilate secondary treatment.
The methods used for primary treatment are-
a) Sedimentation
b) Sedimentation aids
c) Mechanical flocculation
d) Chemical coagulation
e) Coagulants acids
f) Equalization
g) Neutralization
3. Secondary treatment: In this treatment, the dissolved and colloidal organic matter present in waste waters is removed by biological process involving bacteria and other microorganisms. This treatment is of two types-
a) Aerobic process: In this process, bacteria and other microorganisms consume organic matters as food.
i. Activated sludge process
ii. Lagooning process
b) Anaerobic process: This is mainly used for the digestion of sludges.
4. Biochemical treatment :
i. Aerated lagoons
ii. Trickling filters
iii. Activated sludge process
iv. Oxidation ditch process
v. Oxidation pond
vi. Anaerobic digestion
5. Tertiary treatment: Tertiary treatment is the final treatment meant for polishing the effluents from the secondary treatment processes to improve its quality further. The major objectives of tertiary treatment are –
a) Removal of fine suspended solids
b) Removal of bacteria
c) Removal of dissolved inorganic solid
d) Removal of final traces of organic.
The various methods used in sewage and industrial waste water treatment are as follows-
1. Preliminary treatment : The principle objectives of preliminary treatment are the removal of gross solid, i.e., large floating and suspended solid matters, girt, oil and grease if they present in considerable quantities.
2. Primary treatment: After removal of gross solids, gritty materials and excessive quantities of oil and grease, the next step is to remove the remaining suspended solids as much as possible. The step is aimed at reducing the strength of the waste water and also to facilate secondary treatment.
The methods used for primary treatment are-
a) Sedimentation
b) Sedimentation aids
c) Mechanical flocculation
d) Chemical coagulation
e) Coagulants acids
f) Equalization
g) Neutralization
3. Secondary treatment: In this treatment, the dissolved and colloidal organic matter present in waste waters is removed by biological process involving bacteria and other microorganisms. This treatment is of two types-
a) Aerobic process: In this process, bacteria and other microorganisms consume organic matters as food.
i. Activated sludge process
ii. Lagooning process
b) Anaerobic process: This is mainly used for the digestion of sludges.
4. Biochemical treatment :
i. Aerated lagoons
ii. Trickling filters
iii. Activated sludge process
iv. Oxidation ditch process
v. Oxidation pond
vi. Anaerobic digestion
5. Tertiary treatment: Tertiary treatment is the final treatment meant for polishing the effluents from the secondary treatment processes to improve its quality further. The major objectives of tertiary treatment are –
a) Removal of fine suspended solids
b) Removal of bacteria
c) Removal of dissolved inorganic solid
d) Removal of final traces of organic.
Wednesday, August 3, 2011
Water Pollutants
Water Pollutants
Water pollutants mainly classified into five class. These are-
1. Organic pollutants
2. inorganic pollutants
3. Suspended solids and sediment
4. Radio active material
5. Heat
1. Organic pollutants
Organic pollutants may be further categorized as follows
A. Oxygen demanding wastes: these include domestic and animal sewage biodegradable organic compounds and industrial waste, food processing plants, slaughter-houses, paper and pulp mills, tanneries etc. as well as agricultural run-off. All these wastes under degradation and decomposition by bacterial activity in presence of dissolved oxygen.
B. Disease causing waste: These include pathogenic microorganism in which may enter the water along with sewage and other wastes and may cause tremendous damage to public health. These microbes comprising mainly of virus and bacteria can cause dangerous water-born diseases such as cholera, typhoid, dysentery, polio and infections hepatitis in humans.
C. Synthetic organic compound: These are the man-made materials such as synthetic pesticides, synthetic detergent, food-additives, pharmaceuticals, insecticides, paints, synthetic fibers, elastomers, solvents, plasticizers, plastic and other industrial chemicals. Most of these chemicals are potentially toxic to plants, animal and human.
D. Sewage and agricultural run-off: Sewage and run-off from agricultural landssupply plant nutrients, which may stimulate the growth of algae and aquatic weeds in the receiving water body. This unwidely plant-growth results in the degradation of the value of the water body intented for reactional and other uses. Further, the water body loses all its Dissolved Oxygen in the long run up as a dead pool of water.
E. Oil : Oil pollution may take place because of oil spills from cargo oil tankers on the seas, losses during off-shore exploration and production of oil, accidental fires in ships and oil tankers, accidental or intentional oil slicks and leakage from oil pipe line, crossing water ways and reservoirs.
2.Inorganic pollutants
These comprise of mineral acids, inorganic salts, finely devided metals or metal componds, trace elements, cyanides, sulphates, nitrates, organometallic compounds and complexes of metals with organic compound present in the natural water. The trace element include Hg, As, Cd, Pb, Sb, Se etc.
3. Suspended solids and sediment: It denotes the particles floating, immersed and sedimented in the water and water body.
4. Radio-active element: The radio-active water pollutants may originate from anthropogenic activities:
A. Mining or processing of ores e.g., Uranium tailing.
B. Increasing the use of radioactive isotopes in the research, agricultural, industrial and mechanical application.
C. Radioactive material from nuclear power plant and reactor.
D. Radioactive material from testing and use of nuclear weaponry.
5. Heat: Waste heat is produced in all process iin which heat is converted into mechanical work. Thus consideration thermal pollution results from thermal power plants, particularly nuclear power based electrically plants.
Water pollutants mainly classified into five class. These are-
1. Organic pollutants
2. inorganic pollutants
3. Suspended solids and sediment
4. Radio active material
5. Heat
1. Organic pollutants
Organic pollutants may be further categorized as follows
A. Oxygen demanding wastes: these include domestic and animal sewage biodegradable organic compounds and industrial waste, food processing plants, slaughter-houses, paper and pulp mills, tanneries etc. as well as agricultural run-off. All these wastes under degradation and decomposition by bacterial activity in presence of dissolved oxygen.
B. Disease causing waste: These include pathogenic microorganism in which may enter the water along with sewage and other wastes and may cause tremendous damage to public health. These microbes comprising mainly of virus and bacteria can cause dangerous water-born diseases such as cholera, typhoid, dysentery, polio and infections hepatitis in humans.
C. Synthetic organic compound: These are the man-made materials such as synthetic pesticides, synthetic detergent, food-additives, pharmaceuticals, insecticides, paints, synthetic fibers, elastomers, solvents, plasticizers, plastic and other industrial chemicals. Most of these chemicals are potentially toxic to plants, animal and human.
D. Sewage and agricultural run-off: Sewage and run-off from agricultural landssupply plant nutrients, which may stimulate the growth of algae and aquatic weeds in the receiving water body. This unwidely plant-growth results in the degradation of the value of the water body intented for reactional and other uses. Further, the water body loses all its Dissolved Oxygen in the long run up as a dead pool of water.
E. Oil : Oil pollution may take place because of oil spills from cargo oil tankers on the seas, losses during off-shore exploration and production of oil, accidental fires in ships and oil tankers, accidental or intentional oil slicks and leakage from oil pipe line, crossing water ways and reservoirs.
2.Inorganic pollutants
These comprise of mineral acids, inorganic salts, finely devided metals or metal componds, trace elements, cyanides, sulphates, nitrates, organometallic compounds and complexes of metals with organic compound present in the natural water. The trace element include Hg, As, Cd, Pb, Sb, Se etc.
3. Suspended solids and sediment: It denotes the particles floating, immersed and sedimented in the water and water body.
4. Radio-active element: The radio-active water pollutants may originate from anthropogenic activities:
A. Mining or processing of ores e.g., Uranium tailing.
B. Increasing the use of radioactive isotopes in the research, agricultural, industrial and mechanical application.
C. Radioactive material from nuclear power plant and reactor.
D. Radioactive material from testing and use of nuclear weaponry.
5. Heat: Waste heat is produced in all process iin which heat is converted into mechanical work. Thus consideration thermal pollution results from thermal power plants, particularly nuclear power based electrically plants.
COD
COD
COD means chemical oxygen demand. COD is a measure of the oxygen equivalent to that portion of organic matter present in the waste matter sample that is suscsptible to oxidation by potassium dichromate.
Amount of oxygen required by organic matter in a sample of water for its oxidation by strong chemical. Oxidizing agent such as potassium dichromate. According to the ASTM, COD is defined as the amount of oxygen consumed under specified conditions in the oxidation of organic matter and oxidisable inorganic matter, corrected for the influence of chlorine.
COD is important and quickly measured parameter for stream, sewage and industrial waste samples to determine their pollutional strength.
Determination of COD
The principle involved in the determination of COD is that when the waste water sample is refluxed with a known excess of potassium dichromate in a 50% sulphuric acid solution in presence of AgSO4 and HgSO4, the organic matter of the sample is oxidized to water, CO2 and NH3. The excess dichromate remaining unreacted in the solution is titrated with a standard solution of ferrous ammonium sulphate. The COD of the sample is calculated as follows
(V2- V1) × N × 8 × 1000
COD = -----------------------------------------
X
Where, V1 and V2 are volumes of ferrous ammonium sulphate, N is normality run down in the blank and test experients respectively and X is the volume of the sample taken for the test.
COD means chemical oxygen demand. COD is a measure of the oxygen equivalent to that portion of organic matter present in the waste matter sample that is suscsptible to oxidation by potassium dichromate.
Amount of oxygen required by organic matter in a sample of water for its oxidation by strong chemical. Oxidizing agent such as potassium dichromate. According to the ASTM, COD is defined as the amount of oxygen consumed under specified conditions in the oxidation of organic matter and oxidisable inorganic matter, corrected for the influence of chlorine.
COD is important and quickly measured parameter for stream, sewage and industrial waste samples to determine their pollutional strength.
Determination of COD
The principle involved in the determination of COD is that when the waste water sample is refluxed with a known excess of potassium dichromate in a 50% sulphuric acid solution in presence of AgSO4 and HgSO4, the organic matter of the sample is oxidized to water, CO2 and NH3. The excess dichromate remaining unreacted in the solution is titrated with a standard solution of ferrous ammonium sulphate. The COD of the sample is calculated as follows
(V2- V1) × N × 8 × 1000
COD = -----------------------------------------
X
Where, V1 and V2 are volumes of ferrous ammonium sulphate, N is normality run down in the blank and test experients respectively and X is the volume of the sample taken for the test.
BOD
BOD
BOD means Biochemical Oxygen Demand. BOD represents the quantity of oxygen required by bacteria and other microorganisms during the biochemical degradation and transformation of organic matter present in waste water under aerobic conditions.
BOD test is important-
1. In analysis of sewage.
2. In analysis of industrial effluents.
3. In analysis of polluted water.
4. For assessing organic pollution.
5. For containing stream pollution.
Determination of BOD
The BOD test is essentially consists of measurements of dissolved oxygen content of the sample, before and after incubation at 20 °C for 5 days. If the sample does not contain any oxygen, it supplied with oxygen and the depletion caused is calculated as the measure of BOD.
Number of gram of oxygen required
Thus BOD = --------------------------------------------------------------
Number of liters of sample
While carrying out the BOD test, microbial organism may be also be provided if necessary. The BOD is usually expressed as mg/l.
BOD means Biochemical Oxygen Demand. BOD represents the quantity of oxygen required by bacteria and other microorganisms during the biochemical degradation and transformation of organic matter present in waste water under aerobic conditions.
BOD test is important-
1. In analysis of sewage.
2. In analysis of industrial effluents.
3. In analysis of polluted water.
4. For assessing organic pollution.
5. For containing stream pollution.
Determination of BOD
The BOD test is essentially consists of measurements of dissolved oxygen content of the sample, before and after incubation at 20 °C for 5 days. If the sample does not contain any oxygen, it supplied with oxygen and the depletion caused is calculated as the measure of BOD.
Number of gram of oxygen required
Thus BOD = --------------------------------------------------------------
Number of liters of sample
While carrying out the BOD test, microbial organism may be also be provided if necessary. The BOD is usually expressed as mg/l.
Water Pollution and DO
Water Pollution
Any human activity that impairs the use of water as a resource may be called water pollution.
Therefore, addition of excess of undesirable substances to water that makes it harmful to man, animal and aquatic life or other wise causes significant departures from the normal activity of various living communities in and around water is called water pollution.
Dissolved Oxygen
DO means Dissolved Oxygen. The optimum DO in natural waters is 4-6 ppm, which is essential for supporting aquatic life. Any decrease in this DO value is an index of pollution. Many aquatic organisms can not survive at lower DO levels in water.
Determination of Dissolved Oxygen
The DO content of a water sample is determined iodometrically by the Modified Winker’s method. The principle involved in this method is that when manganous sulphate is added to the water sample containing alkaline potassium iodide, manganese hydroxide is formed.
This is oxidized to basic manganic oxide by the DO present in the water sample. When the sulphuric acid is added, the basic manganic oxide liberates iodine, which is equivalent the DO originally present in the water sample. The liberated iodine is titrated with standard hypo solution, using starch as a indicator.
Interference due to nitrate can be determined by adding sodium azide to the alkaline potassium iodide solution used above.
MnSO4 + 2KOH >> Mn(OH)2 + K2SO4
2Mn(OH)2 + O2 (from DO) >> 2MnO(OH)2
2MnO(OH)2 + 2 H2SO4 >> Mn(SO4)2 + H2O
Mn(SO4)2 + KI >> MnSO4 + K2SO4 + I2
2 Na2S2O3 + I2 >> Na2S4O6 + 2NaI
The DO is usually expressed as mg/l (ppm).
Any human activity that impairs the use of water as a resource may be called water pollution.
Therefore, addition of excess of undesirable substances to water that makes it harmful to man, animal and aquatic life or other wise causes significant departures from the normal activity of various living communities in and around water is called water pollution.
Dissolved Oxygen
DO means Dissolved Oxygen. The optimum DO in natural waters is 4-6 ppm, which is essential for supporting aquatic life. Any decrease in this DO value is an index of pollution. Many aquatic organisms can not survive at lower DO levels in water.
Determination of Dissolved Oxygen
The DO content of a water sample is determined iodometrically by the Modified Winker’s method. The principle involved in this method is that when manganous sulphate is added to the water sample containing alkaline potassium iodide, manganese hydroxide is formed.
This is oxidized to basic manganic oxide by the DO present in the water sample. When the sulphuric acid is added, the basic manganic oxide liberates iodine, which is equivalent the DO originally present in the water sample. The liberated iodine is titrated with standard hypo solution, using starch as a indicator.
Interference due to nitrate can be determined by adding sodium azide to the alkaline potassium iodide solution used above.
MnSO4 + 2KOH >> Mn(OH)2 + K2SO4
2Mn(OH)2 + O2 (from DO) >> 2MnO(OH)2
2MnO(OH)2 + 2 H2SO4 >> Mn(SO4)2 + H2O
Mn(SO4)2 + KI >> MnSO4 + K2SO4 + I2
2 Na2S2O3 + I2 >> Na2S4O6 + 2NaI
The DO is usually expressed as mg/l (ppm).
Saturday, July 23, 2011
Photochemical Smog
Photochemical Smog
When atmosphere is loaded with large quantities of automobile exhausts, during warm sunny days with gentle winds and low level inversion, then the exausts gases are trapped by the inversion layers with stagnant air masses and simultaneously exposed to intense sunlight. Then a number of photochemical reactions involving NO2 , hydrocarbons and other organic compound and free radicals take place leading to the formation of ozone, peroxides and other photochemical oxidants in the atmosphere. This gives rises to the phenomenon of photochemical smog which is characterized by the formation of aerosols that reduced visibility, generation of brown hazy fomes that irritate eyes and lungs.
Generally, the smog which is formed by photochemical reaction is known as photochemical smog.
Smoke + Fog >> Smog
The main components of photochemical smog are unsaturated hydrocarbons, NOX, CO and some S compound.
Formation of photochemical smog/PAN
The mechanism of smog formation includes the following steps-
1. Reactive hydrocarbons (which have C=C groups) from automobile exhaust interact with ozone to form Hydrocarbon free radical (RCH2).
2. RCH2 rapidly reacts with oxygen to form another free radical RCH2O2.
3. RCH2O2. rapidly reacts with NO to produce NO2 and free radical RCH2O.
4. This new free radical next interacts with oxygen to yield a stable aldehyde RCHO and hydroperoxy radical HO2.
5. Then HO2. reacts with NO and form NO2 and free radical HO.
6. HO. Is extremely reactive and rapidly reacts with a stable hydrocarbon RCH3 to yield H2O and regenerate the hydrocarbon free radical RCH2., there by completing cycle.
This goes on and on as a chain reactions, one complete cycle yields, two molecules of NO2, one molecule of aldehyde RCHO and regenerate the free radical RCH2 to start all over again, very soon there is rapidly build up of smog product.
7. the aldehyde RCHO may initiate another root by interaction with the HO. Radical, leading to the formation of an acyl radical RC=O which then reacts with oxygen gives peroxyacyl radical (RCOOO). At last this active radical reacts with NO2 and gives peroxy acyl nitrite (PAN).
For Details and Suggestion, please E-mail: zamansgs@gmail.com
When atmosphere is loaded with large quantities of automobile exhausts, during warm sunny days with gentle winds and low level inversion, then the exausts gases are trapped by the inversion layers with stagnant air masses and simultaneously exposed to intense sunlight. Then a number of photochemical reactions involving NO2 , hydrocarbons and other organic compound and free radicals take place leading to the formation of ozone, peroxides and other photochemical oxidants in the atmosphere. This gives rises to the phenomenon of photochemical smog which is characterized by the formation of aerosols that reduced visibility, generation of brown hazy fomes that irritate eyes and lungs.
Generally, the smog which is formed by photochemical reaction is known as photochemical smog.
Smoke + Fog >> Smog
The main components of photochemical smog are unsaturated hydrocarbons, NOX, CO and some S compound.
Formation of photochemical smog/PAN
The mechanism of smog formation includes the following steps-
1. Reactive hydrocarbons (which have C=C groups) from automobile exhaust interact with ozone to form Hydrocarbon free radical (RCH2).
2. RCH2 rapidly reacts with oxygen to form another free radical RCH2O2.
3. RCH2O2. rapidly reacts with NO to produce NO2 and free radical RCH2O.
4. This new free radical next interacts with oxygen to yield a stable aldehyde RCHO and hydroperoxy radical HO2.
5. Then HO2. reacts with NO and form NO2 and free radical HO.
6. HO. Is extremely reactive and rapidly reacts with a stable hydrocarbon RCH3 to yield H2O and regenerate the hydrocarbon free radical RCH2., there by completing cycle.
This goes on and on as a chain reactions, one complete cycle yields, two molecules of NO2, one molecule of aldehyde RCHO and regenerate the free radical RCH2 to start all over again, very soon there is rapidly build up of smog product.
7. the aldehyde RCHO may initiate another root by interaction with the HO. Radical, leading to the formation of an acyl radical RC=O which then reacts with oxygen gives peroxyacyl radical (RCOOO). At last this active radical reacts with NO2 and gives peroxy acyl nitrite (PAN).
For Details and Suggestion, please E-mail: zamansgs@gmail.com
Effects of Photochemical Smog and Composition of Atmosphere
Effect of photochemical smog
The effects of photochemical smog are given below-
• both ozone and PAN cause irritation of eyes creating lachrymation and affect the respiratory tract of human being.
• Photochemical smog oxidizes the cellular constituents of our body and thus destroys them.
• Exposure for a period of two produces extreme fatigue and lack of CO. ordination in central nerves system.
• Inactive the enzyme.(Glucose 6 phosphate dehydrogenase).
• Free radical produced from PAN may destroy DNA.
• Exposure to PAN for several hours causes great loss of vegetation.
• Photochemical smog causes corrosion of metals, stones, building materials, textile etc.
Los Angles Smog
photochemical smog forms a serious air pollution during 1944 in some part of Los Angles, which was characterized by reduced visibility. That is why it is sometimes referred to as Los Angles Smog. It causes eye irritation and plant damage.
Composition of atmosphere
The atmosphere has three categories of constituents-
A. Major constituents-
1. Nitrogen >> 78.09 %
2. Oxygen >> 20.94 %
3. Water Vapour >> 0.1 to 5 %
B. Minor constituents-
1. Argon >> 0.934 %
2. Carbon Dioxide >> 0.0325 %
C. Trace component-
1. Ne >> 0.00182 %
2. He >> 0.000524 %
3. C2H6 >> 0.00018 %
4. Kr >> 0.00011 %
5. N2O >> 0.000025 %
6. Hydrogen >> 0.00005 %
7. CO >> 0.000012 %
8. Xe >> 0.0000087 %
9. Ozone >> 0.000002 %
10. Ammonia >> 0.000001 %
11. SO2 >> 0.0000002 %
12. NO2 >> 0.0000001 %
13. Iodine >> trace amount
For Details and Suggestion, please E-mail: zamansgs@gmail.com
The effects of photochemical smog are given below-
• both ozone and PAN cause irritation of eyes creating lachrymation and affect the respiratory tract of human being.
• Photochemical smog oxidizes the cellular constituents of our body and thus destroys them.
• Exposure for a period of two produces extreme fatigue and lack of CO. ordination in central nerves system.
• Inactive the enzyme.(Glucose 6 phosphate dehydrogenase).
• Free radical produced from PAN may destroy DNA.
• Exposure to PAN for several hours causes great loss of vegetation.
• Photochemical smog causes corrosion of metals, stones, building materials, textile etc.
Los Angles Smog
photochemical smog forms a serious air pollution during 1944 in some part of Los Angles, which was characterized by reduced visibility. That is why it is sometimes referred to as Los Angles Smog. It causes eye irritation and plant damage.
Composition of atmosphere
The atmosphere has three categories of constituents-
A. Major constituents-
1. Nitrogen >> 78.09 %
2. Oxygen >> 20.94 %
3. Water Vapour >> 0.1 to 5 %
B. Minor constituents-
1. Argon >> 0.934 %
2. Carbon Dioxide >> 0.0325 %
C. Trace component-
1. Ne >> 0.00182 %
2. He >> 0.000524 %
3. C2H6 >> 0.00018 %
4. Kr >> 0.00011 %
5. N2O >> 0.000025 %
6. Hydrogen >> 0.00005 %
7. CO >> 0.000012 %
8. Xe >> 0.0000087 %
9. Ozone >> 0.000002 %
10. Ammonia >> 0.000001 %
11. SO2 >> 0.0000002 %
12. NO2 >> 0.0000001 %
13. Iodine >> trace amount
For Details and Suggestion, please E-mail: zamansgs@gmail.com
Thursday, July 21, 2011
Reactions in Atmosphere
Reactions in Atmosphere
The various chemical and photochemical reactions taking place in atmosphere, mostly depends upon, temperature, composition, humidity and intensity of sunlight. Photochemical reaction take place by the absorption of solar radiations in the UV region. Absorption of photons by chemical species gives rise to electrochemically exited molecules, which can bring about cetain reactions. The electrochemically excited molecules may undergo any of the following changes-
• Reaction with other molecules on collision.
• Polymerization.
• Internal rearrangement.
• Dissociation
• De-excitation or de-activation of fluorescence.
Photochemical reaction included the following three steps-
1. absorption of radiation
2. Primary reaction
3. Secondary reaction.
Three steps of compound mainly gives photochemical reaction-
1. reaction involve in oxide of N2 (NO, NO2, NO3 etc)
2. Reaction involve in oxide of sulphuric (SO2, SO3 etc).
3. Oxidation of organic compound.
Reaction involve in oxide of Nitrogen
The oxide of nitrogen in the atmosphere are NO, NO2 and N2O. In the stratosphere N2O undergo photochemical decomposition to NO, which in turn depletes the protective ozone layer.
N2O + hv N2 + O.
N2O + O. N O. + N O.
N O. + O3 NO2 + O2
The most important photochemical reaction is dissociation of NO2
N2O + hv NO + O.
This nitric acid (NO) and pungent red-brown nitrogen dioxide (NO2) are important constituent of polluted air. The NO so formed may be O3 or more slowly by O2. thus leading to a cyclic chain reaction. The chain may be broken when the nitrogen dioxide is completely converted into HNO3 by hydration and cyclic oxidation in presence of fog or photochemical smog.
The reaction may take place are-
2NO + O2 2NO2
NO + O 3 NO2 + O2
2NO2 + O3 N2O5 + O2
4NO2 + O2 + 2H2O 4 HNO3
N2O5 + H2O 2HNO2 + O2
The HNO2 and HNO3 may also undergo photochemical dissociation as follows-
HNO3 + hv NO2 + HO.
HNO2 + hv NO + HO.
HNO2 + hv NO2 + H.
In strarosphere, NO2 may reacts with HO. And form nitric acid.
NO2 + HO. HNO3
The HNO3 so formed as acid rain or is converted into particulate nitrates due to neutralization by NH3 or particulate lime.
Reaction involves oxides of sulphur
SO2 present in the atmosphere, absorb solar radiation in the range of 300-400 nm and produces electrochemically exited ststes of SO2. This undergo oxidation to SO3 and in presence of water vapour
This converted to H2SO4.
SO2 + hv SO2.
SO2. + O2 SO4.
SO4. + O2 SO3 + O3
SO3 + H2O H2SO4
The overall reaction in the presence of sunlight and relative humidity 30-90 % may be represented as-
SO2 + O2 + H2O H2SO4
This photochemical oxidation of SO2 to H2SO4, aerosol is greatly accelerated in the presence of olefinic hydrocarbons and oxides of nitrogen which are usually present photochemically smog.
The oxidation of SO2 also take place by interaction with the free radical HO. Present in photochemical smog.
SO2 + HO. HOSO2.
HOSO2. + O2 HOSO2O2.
HOSO2O2. HOSO2O. + NO2.
In relative humid atmosphere, SO2 may also oxidize by water droplets of aerosols, which are accelerated in presence of ammonia catalysts such as oxides of Mn, Fe, Cu, Ni etc.
NH3 + SO2 + H2O NH4+ + HSO3-
NH3 + HSO3- NH4+ + SO32 –
SO2 is a pollutant responsible for smog formation, acid rain and corrosion of metals and alloys.
Reaction involves in oxidation of organic compound
Organic compounds, e.g., hydrocarbons, aldehyde, ketone, absorb solar radiations and undergo various photochemical and chemical reaction involving free radicals, some of these reactions are catalysed by sort and metal oxides-
CH4 + O2 H3C + HO.
CH4 + HO. H3C + H2O
H3C + O2 + M (third body) H3COO. + M
CH3CH CH2 + HO. CH3C.H CH2OH
RCHO + hv R. + HC.O
RCRO + hv R. + R.CO
RCOOO. + NO RCOOONO2 (peroxyacetyl nitrile PAN)
Where, R is an alkyl or aryl radical or even a H2 atom. The alkyl radical, which may reacts with oxygen to form a peroxy radical, which in turn may reacts with another oxygen atom to give O3. The peroxy radical may reacts with NO2 to give peroxy acyl nitrile(PAN), formaldehyde and various polymeric compounds which reduce visibility.
The various chemical and photochemical reactions taking place in atmosphere, mostly depends upon, temperature, composition, humidity and intensity of sunlight. Photochemical reaction take place by the absorption of solar radiations in the UV region. Absorption of photons by chemical species gives rise to electrochemically exited molecules, which can bring about cetain reactions. The electrochemically excited molecules may undergo any of the following changes-
• Reaction with other molecules on collision.
• Polymerization.
• Internal rearrangement.
• Dissociation
• De-excitation or de-activation of fluorescence.
Photochemical reaction included the following three steps-
1. absorption of radiation
2. Primary reaction
3. Secondary reaction.
Three steps of compound mainly gives photochemical reaction-
1. reaction involve in oxide of N2 (NO, NO2, NO3 etc)
2. Reaction involve in oxide of sulphuric (SO2, SO3 etc).
3. Oxidation of organic compound.
Reaction involve in oxide of Nitrogen
The oxide of nitrogen in the atmosphere are NO, NO2 and N2O. In the stratosphere N2O undergo photochemical decomposition to NO, which in turn depletes the protective ozone layer.
N2O + hv N2 + O.
N2O + O. N O. + N O.
N O. + O3 NO2 + O2
The most important photochemical reaction is dissociation of NO2
N2O + hv NO + O.
This nitric acid (NO) and pungent red-brown nitrogen dioxide (NO2) are important constituent of polluted air. The NO so formed may be O3 or more slowly by O2. thus leading to a cyclic chain reaction. The chain may be broken when the nitrogen dioxide is completely converted into HNO3 by hydration and cyclic oxidation in presence of fog or photochemical smog.
The reaction may take place are-
2NO + O2 2NO2
NO + O 3 NO2 + O2
2NO2 + O3 N2O5 + O2
4NO2 + O2 + 2H2O 4 HNO3
N2O5 + H2O 2HNO2 + O2
The HNO2 and HNO3 may also undergo photochemical dissociation as follows-
HNO3 + hv NO2 + HO.
HNO2 + hv NO + HO.
HNO2 + hv NO2 + H.
In strarosphere, NO2 may reacts with HO. And form nitric acid.
NO2 + HO. HNO3
The HNO3 so formed as acid rain or is converted into particulate nitrates due to neutralization by NH3 or particulate lime.
Reaction involves oxides of sulphur
SO2 present in the atmosphere, absorb solar radiation in the range of 300-400 nm and produces electrochemically exited ststes of SO2. This undergo oxidation to SO3 and in presence of water vapour
This converted to H2SO4.
SO2 + hv SO2.
SO2. + O2 SO4.
SO4. + O2 SO3 + O3
SO3 + H2O H2SO4
The overall reaction in the presence of sunlight and relative humidity 30-90 % may be represented as-
SO2 + O2 + H2O H2SO4
This photochemical oxidation of SO2 to H2SO4, aerosol is greatly accelerated in the presence of olefinic hydrocarbons and oxides of nitrogen which are usually present photochemically smog.
The oxidation of SO2 also take place by interaction with the free radical HO. Present in photochemical smog.
SO2 + HO. HOSO2.
HOSO2. + O2 HOSO2O2.
HOSO2O2. HOSO2O. + NO2.
In relative humid atmosphere, SO2 may also oxidize by water droplets of aerosols, which are accelerated in presence of ammonia catalysts such as oxides of Mn, Fe, Cu, Ni etc.
NH3 + SO2 + H2O NH4+ + HSO3-
NH3 + HSO3- NH4+ + SO32 –
SO2 is a pollutant responsible for smog formation, acid rain and corrosion of metals and alloys.
Reaction involves in oxidation of organic compound
Organic compounds, e.g., hydrocarbons, aldehyde, ketone, absorb solar radiations and undergo various photochemical and chemical reaction involving free radicals, some of these reactions are catalysed by sort and metal oxides-
CH4 + O2 H3C + HO.
CH4 + HO. H3C + H2O
H3C + O2 + M (third body) H3COO. + M
CH3CH CH2 + HO. CH3C.H CH2OH
RCHO + hv R. + HC.O
RCRO + hv R. + R.CO
RCOOO. + NO RCOOONO2 (peroxyacetyl nitrile PAN)
Where, R is an alkyl or aryl radical or even a H2 atom. The alkyl radical, which may reacts with oxygen to form a peroxy radical, which in turn may reacts with another oxygen atom to give O3. The peroxy radical may reacts with NO2 to give peroxy acyl nitrile(PAN), formaldehyde and various polymeric compounds which reduce visibility.
Environmental Segments
Environmental segments
The environmental segments are following below
1. Atmosphere
2. Hydrosphere
3. Biosphere
4. Lithosphere
Atmosphere
The cover of air that envelopes the earth is known as the atmosphere. It is the protective thick gaseous mantle, surrounding the earth, which sustais life on earth and save it from unfriendly environment of outer surface.
Characteristics of atmosphere
1. Weight :( 4.5 to 5) ×105 metric ton.
2. Pressure : 1 atm. to 3× 107 at 100 km above sea level.
3. Temperature:-100 to 1200 °C, depending on altitude.
4. Density : 0.0013 gm/m3
The atmosphere protects the earth from dangerous cosmic radiations. It screens the dangerous radiations from the sun (< 300 nm ) and transmit only 300 nm – 2500 nm radiations. It plays a vital role in maintaining the heat balance on earth by absorbing radiation from sun and earth.
The Atmospheric Structure
Name of the Region Height of the earth
(km) Temperature,°C Major chemical species
Troposphere 1 to 11 15 to -56 O2, N2, CO2, H2O
Stratosphere 11 to 50 -56 to -2 O3
Mesosphere 50 to 85 -2 to -92 O2+ , NO+
Thermosphere 85 to 500 -92 to 1200 O2+ , NO+, O+
Troposphere
This is the nearest region to earth’s surface and extends up to on altitude an altitude of 11 km.
Characteristics
• It is account for over 70% of the total atmospheric mass.
• The temp. of air in this region decreases exponentially with increasing altitude.
• The temperature rages 15 to -56 °C.
• The top of troposphere is troposphere, it makes temp. Inversion.
• Major chemical species are O2, N2, CO2, and H2O.
Stratosphere
The region above tropopause is called stratosphere.
Characteristics
• Height above the earth surface ranges from 11 to 50 km.
• Temperature ranges -56 to -2 °C.
• Due to its low temperature, clouds, dust and water vapor is absent in this region.
• Major chemical species O3.
• The temperature rises with increasing altitude.
• The top of stratosphere is stratopause.
Mesosphere
It is the region above the trapause , it extends up to 85 km height.
Characteristics
• Here temperature decreases with height.
• The decrease in temperature is due to low absorption of UV radiation by ozone.
• Temperature ranges from -2 to -92 °C.
• Mesosphere is the coldest region of atmosphere.
• Major chemical species are O2+, NO+, O+, and N2.
• The layer immediately above the mesosphere is mesospause.
Thermosphere
It is the region immediately above the mesospause.
Characteristics
• The Temperature rises very rapidly with increasing altitude.
• The Temperature ranges from -92 to 1200 °C.
• It extends up to 85 to 500 km.
• It has lower pressure and low density.
• Major chemical species are O2+, NO+, and O+.
The environmental segments are following below
1. Atmosphere
2. Hydrosphere
3. Biosphere
4. Lithosphere
Atmosphere
The cover of air that envelopes the earth is known as the atmosphere. It is the protective thick gaseous mantle, surrounding the earth, which sustais life on earth and save it from unfriendly environment of outer surface.
Characteristics of atmosphere
1. Weight :( 4.5 to 5) ×105 metric ton.
2. Pressure : 1 atm. to 3× 107 at 100 km above sea level.
3. Temperature:-100 to 1200 °C, depending on altitude.
4. Density : 0.0013 gm/m3
The atmosphere protects the earth from dangerous cosmic radiations. It screens the dangerous radiations from the sun (< 300 nm ) and transmit only 300 nm – 2500 nm radiations. It plays a vital role in maintaining the heat balance on earth by absorbing radiation from sun and earth.
The Atmospheric Structure
Name of the Region Height of the earth
(km) Temperature,°C Major chemical species
Troposphere 1 to 11 15 to -56 O2, N2, CO2, H2O
Stratosphere 11 to 50 -56 to -2 O3
Mesosphere 50 to 85 -2 to -92 O2+ , NO+
Thermosphere 85 to 500 -92 to 1200 O2+ , NO+, O+
Troposphere
This is the nearest region to earth’s surface and extends up to on altitude an altitude of 11 km.
Characteristics
• It is account for over 70% of the total atmospheric mass.
• The temp. of air in this region decreases exponentially with increasing altitude.
• The temperature rages 15 to -56 °C.
• The top of troposphere is troposphere, it makes temp. Inversion.
• Major chemical species are O2, N2, CO2, and H2O.
Stratosphere
The region above tropopause is called stratosphere.
Characteristics
• Height above the earth surface ranges from 11 to 50 km.
• Temperature ranges -56 to -2 °C.
• Due to its low temperature, clouds, dust and water vapor is absent in this region.
• Major chemical species O3.
• The temperature rises with increasing altitude.
• The top of stratosphere is stratopause.
Mesosphere
It is the region above the trapause , it extends up to 85 km height.
Characteristics
• Here temperature decreases with height.
• The decrease in temperature is due to low absorption of UV radiation by ozone.
• Temperature ranges from -2 to -92 °C.
• Mesosphere is the coldest region of atmosphere.
• Major chemical species are O2+, NO+, O+, and N2.
• The layer immediately above the mesosphere is mesospause.
Thermosphere
It is the region immediately above the mesospause.
Characteristics
• The Temperature rises very rapidly with increasing altitude.
• The Temperature ranges from -92 to 1200 °C.
• It extends up to 85 to 500 km.
• It has lower pressure and low density.
• Major chemical species are O2+, NO+, and O+.
Contaminant, Receptor, Sink, Treshold limit Value, Lapse Rate and Temperature Inversion
Contaminant
The unfavorable substances which do not occur in nature but are introduced by human activity into the environment (affecting its composition) are known as contaminant.
Example: Chlorine gas(Cl2) which is not present in nature but to the escaption of derailed railway tank car its occurs in nature, which is contaminant.
CFC (Chlorofluoro carbon) one of the most important contaminant is introduced in nature due to the use of the re-frigerator, circular, etc.
The process by which contaminants are introduced in our fresh environment is known as contamination.
Receptor
The medium which accept pollutants is called receptor. Human beings, plants are the example of receptor.
We can also say that the medium which is affected by pollutant is known as receptor.
Sink
The medium which retains and interacts with long live pollutants. A marbal wall will act as a sink for atmospheric sulphuric acid and ultimately get damage.
Threshold limit value
This indicates the permissible level of toxic pollutants in atmosphere to which a healthy industrial worker is exposed during an eight hour day without any adverse effect.
If an industrial environment contain 0.002 mg/m3 Be and 1.00 mg/m3 Zn, then a healthy industrial worker, worked that environment without any adverse effect. Thus the threshold limit vakue for Be is 0.002 mg/m3 and for Zn is 1.00 mg/m3 .
Lapse Rate
The change of atmosphere air temperature with attitude is called lapse rate.
Lapse rate is of two types:
1. Positive Lapse Rate
2. Negative Lapse Rate
Positive Lapse Rate
The decrease of temperature with increasing altitude is called the Positive Lapse Rate.
For example: In troposphere the temperature decreases as 15°C to -56 °C with the increase of altitude. It is positive lapse rate.
Negative Lapse Rate
The increase of temperature with increase of altitude is called negative lapse rate.
For example: In stratosphere, the temperature increases as -56 °C to -2°C as the increase of increase of altitude. Thus this negative lapse rate.
Temperature Inversion
The transition from positive lapse rate to negative lapse rate at the top is called temperature inversion. In other words, the increase of temp. with the increase of altitude is known as temperature inversion. Thus temp. inversion is also called negative lapse rate. Temperature inversion occurs in the atmosphere due to two reactions.
1. Radiation Inversion: This occurs when the air near the earth’s surface get cooled because of the loss of the heat by earth by emitting long wave radiations.
2. Subsidence inversion: This occurs when the upper layers of air subsides during a developing anticyclone.
The unfavorable substances which do not occur in nature but are introduced by human activity into the environment (affecting its composition) are known as contaminant.
Example: Chlorine gas(Cl2) which is not present in nature but to the escaption of derailed railway tank car its occurs in nature, which is contaminant.
CFC (Chlorofluoro carbon) one of the most important contaminant is introduced in nature due to the use of the re-frigerator, circular, etc.
The process by which contaminants are introduced in our fresh environment is known as contamination.
Receptor
The medium which accept pollutants is called receptor. Human beings, plants are the example of receptor.
We can also say that the medium which is affected by pollutant is known as receptor.
Sink
The medium which retains and interacts with long live pollutants. A marbal wall will act as a sink for atmospheric sulphuric acid and ultimately get damage.
Threshold limit value
This indicates the permissible level of toxic pollutants in atmosphere to which a healthy industrial worker is exposed during an eight hour day without any adverse effect.
If an industrial environment contain 0.002 mg/m3 Be and 1.00 mg/m3 Zn, then a healthy industrial worker, worked that environment without any adverse effect. Thus the threshold limit vakue for Be is 0.002 mg/m3 and for Zn is 1.00 mg/m3 .
Lapse Rate
The change of atmosphere air temperature with attitude is called lapse rate.
Lapse rate is of two types:
1. Positive Lapse Rate
2. Negative Lapse Rate
Positive Lapse Rate
The decrease of temperature with increasing altitude is called the Positive Lapse Rate.
For example: In troposphere the temperature decreases as 15°C to -56 °C with the increase of altitude. It is positive lapse rate.
Negative Lapse Rate
The increase of temperature with increase of altitude is called negative lapse rate.
For example: In stratosphere, the temperature increases as -56 °C to -2°C as the increase of increase of altitude. Thus this negative lapse rate.
Temperature Inversion
The transition from positive lapse rate to negative lapse rate at the top is called temperature inversion. In other words, the increase of temp. with the increase of altitude is known as temperature inversion. Thus temp. inversion is also called negative lapse rate. Temperature inversion occurs in the atmosphere due to two reactions.
1. Radiation Inversion: This occurs when the air near the earth’s surface get cooled because of the loss of the heat by earth by emitting long wave radiations.
2. Subsidence inversion: This occurs when the upper layers of air subsides during a developing anticyclone.
Environment/chemistry, Pollution and Pollutant
Environment
The term environment is the sum of all social, economical, biological, physical or chemical factors which is constitute of the surrounding of man, which is both creator or moulder of this environment. It is a holistic view of the world as it functions at anytime with a multitude of special elemental and social-economical systems distinguished by quality and attributes of space and mode behaviour of biotic and abotic forms.
Environmental Chemistry
Environmental Chemistry is a branch of science which deals with the environmental segments, constitutes and it sources. It is not only relates with chemicals but also non-chemist such as material science, engineering etc.
The main object of environmental chemistry is to determine the nature as well as quantity of specific pollutants in the environment.
Basic Concept of Environmental Chemistry
• Environmental Chemistry not only relates with chemist but also non-chemist such as material science, engineering etc.
• Bad effect of environmental chemistry segment on living organism and how to overcome this problem.
Importance/Objectives of Environmental Chemistry
•To determine the nature as well as quality of specific pollutants in the environment.
•To enlighten the public, particularly student about the importance of protection of conservation of our environment and need to restrain human activity which lead to indiscriminate release of pollutants into environment.
• Environmental Chemistry requires high sensitivity & accuracy in determining the environmental pollutants.
Pollution
Pollution means the addition of any foreign materials like organic/inorganic, biological or radiological or any physical change occurring in the nature which may harm or effect living organism directly or indirectly, immediately or after a long time.
The root cause of pollution has been the man’s misbehaviour with the nature.
Pollutants
The materials which cause pollution of environment are called pollutants. Pollutants may be organic/inorganic, biological or radiological unfavourable substances. Pollutants are harmful solid, liquid or gaseous substances present in nature in such concentration which tends to be injuries for the living organism.
Examples: Lead, Mercury, Sulpher-dioxide, carbon monoxide, etc.
Thus we may conclude as such types of substances which are undesirable and present in wrong place at wrong time and wrong quantity in the environment known as pollutants.
Path-ways pollutants
The mechanism by which the pollutants are distributed from its sources in to the environmental segments is known as path-ways of pollutants.
Source > Environment > Receptor
In gasoline/in automobile petrol
Pb(C2H5)4 PbCl3+ PbBr2(Air)
Auto exhausts
To food crops & Food chain PbCl2+PbBr2 (soil)
The term environment is the sum of all social, economical, biological, physical or chemical factors which is constitute of the surrounding of man, which is both creator or moulder of this environment. It is a holistic view of the world as it functions at anytime with a multitude of special elemental and social-economical systems distinguished by quality and attributes of space and mode behaviour of biotic and abotic forms.
Environmental Chemistry
Environmental Chemistry is a branch of science which deals with the environmental segments, constitutes and it sources. It is not only relates with chemicals but also non-chemist such as material science, engineering etc.
The main object of environmental chemistry is to determine the nature as well as quantity of specific pollutants in the environment.
Basic Concept of Environmental Chemistry
• Environmental Chemistry not only relates with chemist but also non-chemist such as material science, engineering etc.
• Bad effect of environmental chemistry segment on living organism and how to overcome this problem.
Importance/Objectives of Environmental Chemistry
•To determine the nature as well as quality of specific pollutants in the environment.
•To enlighten the public, particularly student about the importance of protection of conservation of our environment and need to restrain human activity which lead to indiscriminate release of pollutants into environment.
• Environmental Chemistry requires high sensitivity & accuracy in determining the environmental pollutants.
Pollution
Pollution means the addition of any foreign materials like organic/inorganic, biological or radiological or any physical change occurring in the nature which may harm or effect living organism directly or indirectly, immediately or after a long time.
The root cause of pollution has been the man’s misbehaviour with the nature.
Pollutants
The materials which cause pollution of environment are called pollutants. Pollutants may be organic/inorganic, biological or radiological unfavourable substances. Pollutants are harmful solid, liquid or gaseous substances present in nature in such concentration which tends to be injuries for the living organism.
Examples: Lead, Mercury, Sulpher-dioxide, carbon monoxide, etc.
Thus we may conclude as such types of substances which are undesirable and present in wrong place at wrong time and wrong quantity in the environment known as pollutants.
Path-ways pollutants
The mechanism by which the pollutants are distributed from its sources in to the environmental segments is known as path-ways of pollutants.
Source > Environment > Receptor
In gasoline/in automobile petrol
Pb(C2H5)4 PbCl3+ PbBr2(Air)
Auto exhausts
To food crops & Food chain PbCl2+PbBr2 (soil)
Tuesday, July 12, 2011
Microbial degradation and degradation product
Microbial degradation of some odorous substances and the degradation product
Serial No. Substrate Microorganism Degradation products
1 Phenol Pseudomonas Putida
Trichosporon Cutaneum Aldehyde and pyrovate Acetyl CoA and Succinate
2 Dimethyl sulphide Hypomicrobium SPP H2SO4, SO2, CO2
3 Pyridine, 4-methyl pyridine Pseudomonas SPP
4 Dimethyl amine Pseudomonas aminovorans Methyl amine and formaldehyde
5 Anilline Nocardia SPP Pyrocatechol
6 Benzaldehyde Acetobactor asendens Benzylalcohol and benzoic acid
7 Indole Chromobacterium violaceum Tryptophan
8 n-propyl amine Microbacterium convolutum Propionate
Serial No. Substrate Microorganism Degradation products
1 Phenol Pseudomonas Putida
Trichosporon Cutaneum Aldehyde and pyrovate Acetyl CoA and Succinate
2 Dimethyl sulphide Hypomicrobium SPP H2SO4, SO2, CO2
3 Pyridine, 4-methyl pyridine Pseudomonas SPP
4 Dimethyl amine Pseudomonas aminovorans Methyl amine and formaldehyde
5 Anilline Nocardia SPP Pyrocatechol
6 Benzaldehyde Acetobactor asendens Benzylalcohol and benzoic acid
7 Indole Chromobacterium violaceum Tryptophan
8 n-propyl amine Microbacterium convolutum Propionate
Bioremediation and Deodorization
Bioremediation
Bioremediation is the use of biological system for the reduction of pollution from air or from aquatic system. Microorganism and plants are the biological systems which are generally used. Bio-degradation with microorganism with is the most frequently occurring bioremediation option. Microorganosm can break down most compounds for their growth and energy need. Bioremediation is the microbial clean up approach. It employs biological agents to render hazardous waste to non-hazardous or less hazardous waste. Microbs can acclimatize themselves to toxic wastes and new resistant strains develop naturally. Such strains can be used for pollution control and environmental protection.
Examples
• Some of algae and bacteria can accumulate large quanties of metals. Such as pseudomonous aerugensa can accumulate Uranium and thiobacillus can accumulate silver.
• Mixture of microbes and enzymes are used to clean up chemical wastes such as detergent, pesticides, etc.
Biological deodorization
Deodorization process include physical, chemical and biological. In biological deodorization, fuel smelling compounds are decomposed by exploiting metabolic process of the microorganisms. An exhaust gas treatment system for H2S and SO2 based on Thiobacillus ferroxidan bacteria is already practice in Japan.
Bioscubbing involves scrubbing of waste effluents using microbial methods to detoxify or de-odourise certain constituents in the waste effluents. Hypomcrobium SSP can be used to oxidize the malodourous dimethylsulphide aerobically or anaerobically.
Aerobic process H2S + 2O2 H2SO4
(CH3)2S + SO2 H2SO4 + 2CO2 + 2H2O
Anaerobic process
Hypomicrobium
5H2S + 8 NaNO2 H2SO4 + 4NaSO4 + 4N2 + 4H2O
SSP
(CH3)2S + 4NaNO2 NaSO4 + 2 CO2 + 2N2 + 2NaOH + 2H2O
Bioremediation is the use of biological system for the reduction of pollution from air or from aquatic system. Microorganism and plants are the biological systems which are generally used. Bio-degradation with microorganism with is the most frequently occurring bioremediation option. Microorganosm can break down most compounds for their growth and energy need. Bioremediation is the microbial clean up approach. It employs biological agents to render hazardous waste to non-hazardous or less hazardous waste. Microbs can acclimatize themselves to toxic wastes and new resistant strains develop naturally. Such strains can be used for pollution control and environmental protection.
Examples
• Some of algae and bacteria can accumulate large quanties of metals. Such as pseudomonous aerugensa can accumulate Uranium and thiobacillus can accumulate silver.
• Mixture of microbes and enzymes are used to clean up chemical wastes such as detergent, pesticides, etc.
Biological deodorization
Deodorization process include physical, chemical and biological. In biological deodorization, fuel smelling compounds are decomposed by exploiting metabolic process of the microorganisms. An exhaust gas treatment system for H2S and SO2 based on Thiobacillus ferroxidan bacteria is already practice in Japan.
Bioscubbing involves scrubbing of waste effluents using microbial methods to detoxify or de-odourise certain constituents in the waste effluents. Hypomcrobium SSP can be used to oxidize the malodourous dimethylsulphide aerobically or anaerobically.
Aerobic process H2S + 2O2 H2SO4
(CH3)2S + SO2 H2SO4 + 2CO2 + 2H2O
Anaerobic process
Hypomicrobium
5H2S + 8 NaNO2 H2SO4 + 4NaSO4 + 4N2 + 4H2O
SSP
(CH3)2S + 4NaNO2 NaSO4 + 2 CO2 + 2N2 + 2NaOH + 2H2O
Bioinformatics and Biosensors
Bio-informatics
Bio-informatics is an interdisciplinary field which addresses biological problems using computations techniques and makes the rapid organization and analysis of biological data possible. The field may also be referred to as computational biology and can be defined as—
“Conceptualizing biology in terms of molecules and then applying informatics technique to understand and organize the information associated with these molecules on a large scale.”
Bio-informatics plays a key role in various areas such as functional genomics, structural genomcs and proteomics and forms a key component in the biotechnology and pharmaceutical sector.
Biosensor
A biosensor is an analytical gadget comprising of an immobilized layer of a biological material (Example: enzyme, antibody, hormone) inconjunction with a transducer which analyses the biological signals and converts them into an electrical signal.
Example: BOD sensor, Nitrate sensor, Ammonia sensor, sulfide ion sensor.
Bio-sensor works on the following principle
A layer of suitable biological material is immobilized on a permeable membrane which is kept in the close vicinity of a sensor. The substance to be measured passes through the membrane and interact with the immobilized material and yield a product. The product passes through another membrane to the transducer. The transducer converts into an clectrical signal which is amplified and displayed or recorder.
Bio-informatics is an interdisciplinary field which addresses biological problems using computations techniques and makes the rapid organization and analysis of biological data possible. The field may also be referred to as computational biology and can be defined as—
“Conceptualizing biology in terms of molecules and then applying informatics technique to understand and organize the information associated with these molecules on a large scale.”
Bio-informatics plays a key role in various areas such as functional genomics, structural genomcs and proteomics and forms a key component in the biotechnology and pharmaceutical sector.
Biosensor
A biosensor is an analytical gadget comprising of an immobilized layer of a biological material (Example: enzyme, antibody, hormone) inconjunction with a transducer which analyses the biological signals and converts them into an electrical signal.
Example: BOD sensor, Nitrate sensor, Ammonia sensor, sulfide ion sensor.
Bio-sensor works on the following principle
A layer of suitable biological material is immobilized on a permeable membrane which is kept in the close vicinity of a sensor. The substance to be measured passes through the membrane and interact with the immobilized material and yield a product. The product passes through another membrane to the transducer. The transducer converts into an clectrical signal which is amplified and displayed or recorder.
Biotechnology on pollution control
Biotechnology on pollution control
Biotechnology compromise of integrated application of theoretical and practical knowledge of biochemistry, microbiology, physiology, genetics and chemical engineering to exploit the properties of microbes and cultures for various beneficial technological uses. Environmental biotechnology is a very broad field which includes environmental monitoring and safety, waste treatment recovery, restoration of environment quality. Substitution of non-renewable resource-base with renewable resources, research and development of various processes for the benefit of mankind with due regard to socio-economic legal and environment safety consideration.
Important applications of biotechnology in pollution control and waste management include
A. Improvement of existing processes
Example: uses of bio-science and biochemical engineering to obtain knowledge about applicaton of mixed cultures such as-
• Improvement in sewage treatment
• Use of starter cultures for tratement processes
• Used in immobilized microbial cells in waste water treatment.
B. Treatment of toxic wastes using genetically improved organism:
Example: Genes which can bring about degradation of toxic environmental pollution(Such as toluene, chloro-organics etc.) have indentified. For degradation of toxic chemials, enzymes are encloded by specific gene present in plasmid. Such as-
• OCT plasmid degrades oxane, hexane and decame.
• XYL plasmid degrades xylenes & toluenes.
• CAM plasmid decompose camphor.
• NAH plasmid degrades naphthalene.
C. Recoveryly of useful product from waste material.
Example: Recovery of methane, metals etc. from waste material.
D. Development of new catalysts, new bioreactors, novel biosensors and automation of waste water treatment process.
Example
• Use of immobilized organisms and heavy metals as new catalyst and bioreactors.
• Use of trace of toxic organic as new sensor.
• Design of cadmium binding synthetic adsorbent.
Biotechnology compromise of integrated application of theoretical and practical knowledge of biochemistry, microbiology, physiology, genetics and chemical engineering to exploit the properties of microbes and cultures for various beneficial technological uses. Environmental biotechnology is a very broad field which includes environmental monitoring and safety, waste treatment recovery, restoration of environment quality. Substitution of non-renewable resource-base with renewable resources, research and development of various processes for the benefit of mankind with due regard to socio-economic legal and environment safety consideration.
Important applications of biotechnology in pollution control and waste management include
A. Improvement of existing processes
Example: uses of bio-science and biochemical engineering to obtain knowledge about applicaton of mixed cultures such as-
• Improvement in sewage treatment
• Use of starter cultures for tratement processes
• Used in immobilized microbial cells in waste water treatment.
B. Treatment of toxic wastes using genetically improved organism:
Example: Genes which can bring about degradation of toxic environmental pollution(Such as toluene, chloro-organics etc.) have indentified. For degradation of toxic chemials, enzymes are encloded by specific gene present in plasmid. Such as-
• OCT plasmid degrades oxane, hexane and decame.
• XYL plasmid degrades xylenes & toluenes.
• CAM plasmid decompose camphor.
• NAH plasmid degrades naphthalene.
C. Recoveryly of useful product from waste material.
Example: Recovery of methane, metals etc. from waste material.
D. Development of new catalysts, new bioreactors, novel biosensors and automation of waste water treatment process.
Example
• Use of immobilized organisms and heavy metals as new catalyst and bioreactors.
• Use of trace of toxic organic as new sensor.
• Design of cadmium binding synthetic adsorbent.
Biotechnology and pllution control
Environmental biotechnology and biotechnology
Environmental Biotechnology: The application of biotechnology in the natural environment is called environmental biotechnology .This could be primarily sustaining the environment by using eco-friendly biological process. Some of these processes could be used to solve the most demanding environment problems like enrolling air emissions and water pollution.
Bio-technology: Bio-technology is a field of applied biology that involves the use of living organisms and bioprocesses in engineering technology medicine and other fields requiring bio-products.
The United Nations Convention on Biological Diversity (UNCBD) defines biotechnology as
“Any technological application that uses biological systems living organisms or derivatives there of to modify product or process for specific use.”
Application of biotechnology in Environment protection
The Application f bio technologies in environment protection are
1. It is used for the treatment of municipal sewage treatment plants and filters to purify town gas.
2. Bio-technological techniques to treat waste before or after it has been brought into the environment.
3. Domestic solid waste may also treated by this process.
4. Toxic waste many also be neutralize by using micro-organism.
5. Micro-organism may also be used to treat the common pollutant in Industrial effluent before discharging it into water.
For more information and suggestion : zamansgs@gmail.com
Environmental Biotechnology: The application of biotechnology in the natural environment is called environmental biotechnology .This could be primarily sustaining the environment by using eco-friendly biological process. Some of these processes could be used to solve the most demanding environment problems like enrolling air emissions and water pollution.
Bio-technology: Bio-technology is a field of applied biology that involves the use of living organisms and bioprocesses in engineering technology medicine and other fields requiring bio-products.
The United Nations Convention on Biological Diversity (UNCBD) defines biotechnology as
“Any technological application that uses biological systems living organisms or derivatives there of to modify product or process for specific use.”
Application of biotechnology in Environment protection
The Application f bio technologies in environment protection are
1. It is used for the treatment of municipal sewage treatment plants and filters to purify town gas.
2. Bio-technological techniques to treat waste before or after it has been brought into the environment.
3. Domestic solid waste may also treated by this process.
4. Toxic waste many also be neutralize by using micro-organism.
5. Micro-organism may also be used to treat the common pollutant in Industrial effluent before discharging it into water.
For more information and suggestion : zamansgs@gmail.com
Tuesday, June 28, 2011
Measurement of Tensile Strength
Measurement of Tensile Strength
Okra bast fibres were cut into small pieces of length 30 cm and the length of each specimen between the jaws of the machine was maintained 10 cm. One twist per 2 cm was given along the length of the fibre between the jaws of the machine for measuring breaking strength of okra bast fibre. 0.5 gm of each specimen was weight out and the tensile strength of it was measured (by Torsee,s Scopper Type-OS-100). The breaking load was gradually increased after starting the machine and at a particular point the specimen was broken down. The machine was stopped at the point of break. The breaking load was shown on the scale of the tensile tester in N. In each experiment tensile strength for 10 cm specimens were taken and the mean of 10 readings was the breaking strength of okra bast fibre.
Knowing the breaking load, the tensile strength/tenacity was calculated by the following formula:
Tenacity = Average breaking load /Denier (gm/denier)
From the weight and length, the denier of okra bast fibre sample was calculated according to the formula:
Denier = Weight of sample in gm/Length of the sample in meter x 9000
Weight and length of the sample were measured between the jaws of the tensile strength tester. By calculating average breaking strength and denier, tensile strength or tenacity of undyed and dyed bleached and modified okra bast fibres were measured.
Okra bast fibres were cut into small pieces of length 30 cm and the length of each specimen between the jaws of the machine was maintained 10 cm. One twist per 2 cm was given along the length of the fibre between the jaws of the machine for measuring breaking strength of okra bast fibre. 0.5 gm of each specimen was weight out and the tensile strength of it was measured (by Torsee,s Scopper Type-OS-100). The breaking load was gradually increased after starting the machine and at a particular point the specimen was broken down. The machine was stopped at the point of break. The breaking load was shown on the scale of the tensile tester in N. In each experiment tensile strength for 10 cm specimens were taken and the mean of 10 readings was the breaking strength of okra bast fibre.
Knowing the breaking load, the tensile strength/tenacity was calculated by the following formula:
Tenacity = Average breaking load /Denier (gm/denier)
From the weight and length, the denier of okra bast fibre sample was calculated according to the formula:
Denier = Weight of sample in gm/Length of the sample in meter x 9000
Weight and length of the sample were measured between the jaws of the tensile strength tester. By calculating average breaking strength and denier, tensile strength or tenacity of undyed and dyed bleached and modified okra bast fibres were measured.
Degradation Method
Degradation Method
Thermo-oxidative Degradation
The thermo-oxidative degradation of undyed, bleached dyed and modified okra bast fibres were studied. Okra bast fibres were cut into equal length of 30 cm and placed in an electric oven in presence of air. After heating the experimental samples at 50, 100, 150, 200 and 250°C for 1 h, the fibre samples were collected. The change in colour of samples were assessed with Grey Scale.
Photo-Oxidative Degradation
Both undyed and bleached dyed and modified okra bast fibres were attached on a flat board separately and placed on the roof of a building for exposure in open air under the sun for 50, 100, 150, 200 and 250 hours without any protection from weather. Care was taken so that the effect of weathering would be confined to the surface of the fibre. After exposing the fibres were collected from the board for experimental purpose. The change in colour of samples was assessed with Grey Scale.
Thermo-oxidative Degradation
The thermo-oxidative degradation of undyed, bleached dyed and modified okra bast fibres were studied. Okra bast fibres were cut into equal length of 30 cm and placed in an electric oven in presence of air. After heating the experimental samples at 50, 100, 150, 200 and 250°C for 1 h, the fibre samples were collected. The change in colour of samples were assessed with Grey Scale.
Photo-Oxidative Degradation
Both undyed and bleached dyed and modified okra bast fibres were attached on a flat board separately and placed on the roof of a building for exposure in open air under the sun for 50, 100, 150, 200 and 250 hours without any protection from weather. Care was taken so that the effect of weathering would be confined to the surface of the fibre. After exposing the fibres were collected from the board for experimental purpose. The change in colour of samples was assessed with Grey Scale.
Colour Fastness to Spotting: Acid and Alkali
Colour Fastness to Spotting: Acid and Alkali
Undyed and dyed (bleached & modified) okra bast fibres were combed and compressed enough to form a sheet of 10 cm × 4 cm. The specimens were spotted with two drops of acid or alkali solution at room temperature. The surface of the specimens were gently rubbed with the glass rod to ensure penetration. The specimens were dried by hanging them in open air at room temperature. The change in colour of the specimens was assessed after drying with Grey Scale. In the same way, the change in colour was assessed by the solution given below.
(i) Acetic acid solution containing 10 g/l.
(ii) Nitric acid solution containing 10 g/l.
(iii) Sulphuric acid solution containing 10 g/l.
(iv) Sodium carbonate solution containing 10 g/l.
(v) Ammonia solution containing 10 g/l.
(vi) Sodium hydroxide solution containing 10 g/l.
Undyed and dyed (bleached & modified) okra bast fibres were combed and compressed enough to form a sheet of 10 cm × 4 cm. The specimens were spotted with two drops of acid or alkali solution at room temperature. The surface of the specimens were gently rubbed with the glass rod to ensure penetration. The specimens were dried by hanging them in open air at room temperature. The change in colour of the specimens was assessed after drying with Grey Scale. In the same way, the change in colour was assessed by the solution given below.
(i) Acetic acid solution containing 10 g/l.
(ii) Nitric acid solution containing 10 g/l.
(iii) Sulphuric acid solution containing 10 g/l.
(iv) Sodium carbonate solution containing 10 g/l.
(v) Ammonia solution containing 10 g/l.
(vi) Sodium hydroxide solution containing 10 g/l.
Colour Fastness to Sunlight
Colour Fastness to Sunlight
Light fastness test was carried out of both the bleached dyed and modified dyed fibres. Specimens of the fibre were attached separately on a board by a glass rod and placed on the roof of a building for exposure in the open air under the sun without any protection from weathering, but was protected form rain, dews,dust etc. The specimens were exposed under the sun for seven hours each day and continued for 250 h. After every 50 h, the fastness was assessed by comparing the change in colour of specimen with that of the standard or original.
Measurement of DL*, Da*and Db*
In addition to visual assessments, the samples were evaluated objectly by measuring the CIE Lab values (DL*, Da*and Db*) of dyed samples before and after washing using a Macbath CE-3100 spectrometer and then calculating the colour change. Illuminant D65 and 10° observer geometry were used throughout for the colour measurement.
Light fastness test was carried out of both the bleached dyed and modified dyed fibres. Specimens of the fibre were attached separately on a board by a glass rod and placed on the roof of a building for exposure in the open air under the sun without any protection from weathering, but was protected form rain, dews,dust etc. The specimens were exposed under the sun for seven hours each day and continued for 250 h. After every 50 h, the fastness was assessed by comparing the change in colour of specimen with that of the standard or original.
Measurement of DL*, Da*and Db*
In addition to visual assessments, the samples were evaluated objectly by measuring the CIE Lab values (DL*, Da*and Db*) of dyed samples before and after washing using a Macbath CE-3100 spectrometer and then calculating the colour change. Illuminant D65 and 10° observer geometry were used throughout for the colour measurement.
Measurement of Colour Strength (K/S value)
Measurement of Colour Strength (K/S value)
The colour yield of both bleached and grafted dyed fibres was evaluated by light reflectance measurements using Macbeth CE-3100 spectrometer.
The colour strength (K/S) value was assesed using the Kubelka-Munk equation:
(1-R)(1-R)
K/S =-------------
2R
Where R is the decimal fraction of the reflectance of dyed fibre.
The colour yield of both bleached and grafted dyed fibres was evaluated by light reflectance measurements using Macbeth CE-3100 spectrometer.
The colour strength (K/S) value was assesed using the Kubelka-Munk equation:
(1-R)(1-R)
K/S =-------------
2R
Where R is the decimal fraction of the reflectance of dyed fibre.
Method of Dyeing
Method of Dyeing
Direct green 27 and Direct Red 28 were dissolved at first by making paste with little distilled water and then by adding cold distilled water, the dye baths were prepared by taking 5 % dye concentration and 5% electrolyte (Na2SO4) concentration (on the basis of weight of okra fibre). The fibre-liquor ratio was maintained at 1:50. Before immersing the fibre in the dye bath it was treated well in distilled water and squeezed for even absorption of dye particles. Dyeing temperature was fixed at 70°C and it was continued for 60 min. The dye bath was occasional stirring by a glass rod and then allowed for further 30 min as the bath cools down. During dyeing the dye bath were slightly alkaline with 2% sodium carbonate solution to attain the fast reaction and also hot distilled water was added to the dye bath in order to maintain the fibre-liquor ratio 1:50 throughout the experiment.
Direct green 27 and Direct Red 28 were dissolved at first by making paste with little distilled water and then by adding cold distilled water, the dye baths were prepared by taking 5 % dye concentration and 5% electrolyte (Na2SO4) concentration (on the basis of weight of okra fibre). The fibre-liquor ratio was maintained at 1:50. Before immersing the fibre in the dye bath it was treated well in distilled water and squeezed for even absorption of dye particles. Dyeing temperature was fixed at 70°C and it was continued for 60 min. The dye bath was occasional stirring by a glass rod and then allowed for further 30 min as the bath cools down. During dyeing the dye bath were slightly alkaline with 2% sodium carbonate solution to attain the fast reaction and also hot distilled water was added to the dye bath in order to maintain the fibre-liquor ratio 1:50 throughout the experiment.
Measurement of Water Absorption
Method for the measurement of water absorption
Water absorption tests of untreated and chemically modified okra bast fibres are carried out by taking a small amount (about 0.5 g) of the fibre. Fibre samples were first dried by heating in an electric oven at 70°C for about 2 h, weighed and then soaked in a bath of conductivity water at room temperature. After 24 h, the fibre samples were removed from water, dried by a cotton cloth and weighed again.
A-B
Percentage of water absorption by fibres =------------100
B
Where,
A = The weight of the fibres after water absorption.
B = The weight of the fibres before water absorption
(drying sample).
Water absorption tests of untreated and chemically modified okra bast fibres are carried out by taking a small amount (about 0.5 g) of the fibre. Fibre samples were first dried by heating in an electric oven at 70°C for about 2 h, weighed and then soaked in a bath of conductivity water at room temperature. After 24 h, the fibre samples were removed from water, dried by a cotton cloth and weighed again.
A-B
Percentage of water absorption by fibres =------------100
B
Where,
A = The weight of the fibres after water absorption.
B = The weight of the fibres before water absorption
(drying sample).
Scanning Electron Microscopy (SEM)
Scanning Electron Microscopy (SEM)
A scanning electron microscopy (SEM) machine was used to study the surface morphology of the acrylonitrile treated OBF. The microscopic utmost importance in characterizing the structural changes that have occurred upon treatment.
Scanning Electron Microscope:
Model: Philips XL-30
Specification of SEM: Magnification 100000X
Excitation voltage 30 kv
Equipped with vacuum pump
Equipped with EDS
A scanning electron microscopy (SEM) machine was used to study the surface morphology of the acrylonitrile treated OBF. The microscopic utmost importance in characterizing the structural changes that have occurred upon treatment.
Scanning Electron Microscope:
Model: Philips XL-30
Specification of SEM: Magnification 100000X
Excitation voltage 30 kv
Equipped with vacuum pump
Equipped with EDS
Fourier Transform Infrared Spectroscopy (FTIR) measurement
Fourier Transform Infrared Spectroscopy (FTIR) measurement
The measurements were performed using a Shemazdu Spectrometer. A total 100 scans were taken with a resolution of 2 cm-1 for each sample. The fibre was cut in a size range between 106 and 212 micrometer. A mixture of 5.0 mg of dried fibres and 200 mg of KBr was pressed into a disk for FTIR measurement.
The measurements were performed using a Shemazdu Spectrometer. A total 100 scans were taken with a resolution of 2 cm-1 for each sample. The fibre was cut in a size range between 106 and 212 micrometer. A mixture of 5.0 mg of dried fibres and 200 mg of KBr was pressed into a disk for FTIR measurement.
Method of Modification of Okra Bast Fiber
Method of Modification of Okra Bast Fiber
Vinyl monomer (Acrylonitrile) was dissolved in cold distilled water. Initiator and catalyst solutions were also prepared with cold distilled water. The modifying baths were prepared by adding required amount of monomer, initiator and catalyst. The fibre-liquor ratio was maintained at 1:50. Modification was started at 30°C and then the temperature was slowly increased upto 90°C with 30 min and continued for 240 min with occasional stirring by a glass rod and allowed for further 30 min as the bath cools down. Hot distilled water was added to the modifying baths in order to maintain the fibre-liquor ratio 1:50 throughout the experiment. After modification the fibres were washed with hot distilled water to remove the suspended homopolymer on the okra bast fibre sample and dried at room temperature.
Percentage of grafting was calculated according to the following formula:
A-B
Percentage of grafting = ---------- 100
B
Where,
A = The weight of the okra bast fibre after modification
B = The weight of bleached okra bast fibre before modification
Selection of Optimum Modification Conditions
In order to select the optimum conditions of modification of okra bast fibre, monomer concentration, initiator concentration, catalyst concentration, modification time and modification temperature were selected accordingly.
Selection of Monomer Concentration
Ten baths were prepared with 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M and 0.1M acrylonitrile monomer. Keeping constant all other parameters (Initiator 0.1M, catalyst-0.1M, time 90 min, temperature 70°C, fibre-liquor ratio1:50), the monomer concentration which gave the maximum percentage of grafting was selected for modification.
Selection of Initiator Concentration
The selected monomer concentration and other parameters (catalyst 0.1M, time 90 min, temperature 70°C, fibre-liquor ratio 1:50) were kept constant and the ten modifying baths were prepared with 0.001M, 0.005M, 0.01M, 0.015M, 0.02M, 0.025M, 0.03M, 0.035M, 0.04, and 0.045M potassium persulphate (K2S2O8) initiator solution. The initiator concentration which gave the maximum grafting was selected for modification.
Selection of Catalyst Concentration
The selected monomer and initiator concentration and other parameters (time 90 min, temperature 70°C, fibre-liquor ratio 1:50) were kept constant and then ten modifying baths were prepared with 0.001M, 0.002M, 0.003M,
0.004M, 0.006M, 0.007M, 0.008M, 0.009M, 0.01M,and 0.02M ferrous sulphate (FeSO4) as catalyst to catalyse the initiator. The catalyst concentration which gave the maximum grafting was selected for modification.
Selection of Modification Time
Eight modifying baths each containing selected monomer, initiator and catalyst concentrations were prepared and the fibres were modified at 70°C for 30, 60, 90, 120, 150, 180, 210 and 240 min. The time of modification which gave maximum grafting was selected for modification.
Selection of Modification Temperature
Seven modifying baths, each containing selected monomer, initiator and catalyst concentrations were prepared and then the okra fibre were modified at 30° (room temperature), 40°, 50°, 60°, 70°, 80° and 90°C for selected time. The temperature, which gave maximum grafting, was selected for modification.
Vinyl monomer (Acrylonitrile) was dissolved in cold distilled water. Initiator and catalyst solutions were also prepared with cold distilled water. The modifying baths were prepared by adding required amount of monomer, initiator and catalyst. The fibre-liquor ratio was maintained at 1:50. Modification was started at 30°C and then the temperature was slowly increased upto 90°C with 30 min and continued for 240 min with occasional stirring by a glass rod and allowed for further 30 min as the bath cools down. Hot distilled water was added to the modifying baths in order to maintain the fibre-liquor ratio 1:50 throughout the experiment. After modification the fibres were washed with hot distilled water to remove the suspended homopolymer on the okra bast fibre sample and dried at room temperature.
Percentage of grafting was calculated according to the following formula:
A-B
Percentage of grafting = ---------- 100
B
Where,
A = The weight of the okra bast fibre after modification
B = The weight of bleached okra bast fibre before modification
Selection of Optimum Modification Conditions
In order to select the optimum conditions of modification of okra bast fibre, monomer concentration, initiator concentration, catalyst concentration, modification time and modification temperature were selected accordingly.
Selection of Monomer Concentration
Ten baths were prepared with 0.01M, 0.02M, 0.03M, 0.04M, 0.05M, 0.06M, 0.07M, 0.08M, 0.09M and 0.1M acrylonitrile monomer. Keeping constant all other parameters (Initiator 0.1M, catalyst-0.1M, time 90 min, temperature 70°C, fibre-liquor ratio1:50), the monomer concentration which gave the maximum percentage of grafting was selected for modification.
Selection of Initiator Concentration
The selected monomer concentration and other parameters (catalyst 0.1M, time 90 min, temperature 70°C, fibre-liquor ratio 1:50) were kept constant and the ten modifying baths were prepared with 0.001M, 0.005M, 0.01M, 0.015M, 0.02M, 0.025M, 0.03M, 0.035M, 0.04, and 0.045M potassium persulphate (K2S2O8) initiator solution. The initiator concentration which gave the maximum grafting was selected for modification.
Selection of Catalyst Concentration
The selected monomer and initiator concentration and other parameters (time 90 min, temperature 70°C, fibre-liquor ratio 1:50) were kept constant and then ten modifying baths were prepared with 0.001M, 0.002M, 0.003M,
0.004M, 0.006M, 0.007M, 0.008M, 0.009M, 0.01M,and 0.02M ferrous sulphate (FeSO4) as catalyst to catalyse the initiator. The catalyst concentration which gave the maximum grafting was selected for modification.
Selection of Modification Time
Eight modifying baths each containing selected monomer, initiator and catalyst concentrations were prepared and the fibres were modified at 70°C for 30, 60, 90, 120, 150, 180, 210 and 240 min. The time of modification which gave maximum grafting was selected for modification.
Selection of Modification Temperature
Seven modifying baths, each containing selected monomer, initiator and catalyst concentrations were prepared and then the okra fibre were modified at 30° (room temperature), 40°, 50°, 60°, 70°, 80° and 90°C for selected time. The temperature, which gave maximum grafting, was selected for modification.
Bleaching of Okra with Sodium Chlorite
Bleaching of Okra Bast Fibre With Sodium Chlorite
For bleaching, about 1 gm dewaxed okra bast fibre dried at 105°C was treated with 0.7% sodium chlorite (NaClO2) solution buffered at pH 4. Required amount of sodium chlorite was dissolved in a known volume of water, and its pH, which was 10.6, was lowered to 4 by the gradual addition of 0.2N acetic acid. pH readings were taken with pH meter (Pocket). The pH meter was standardized with a buffer solution of known pH and was checked
with another buffer solution of known pH. A buffer mixture of pH 4 (acetic acid-sodium acetate) was prepared and added to the chlorite CH3COOH-CH3COONa buffer solution in the proportion of 1 ml of buffer solution for every 10 ml of chlorite solution, to ensure that pH remained at 4 throughout the progress of the reaction. This pH maintaining is necessary because many organic acids are liberated during bleaching and unless the mixture is buffered the pH of the medium would change. The bleaching process was carried out by digesting the fiber for about 2 h at 90-95°C. For each gram of the fiber 80 ml of the mixture was used. After bleaching the fibre was filtered over a sintered funnel and washed thoroughly with distilled water. It was then treated with 2% sodium metabisulphite solution for 15 min. The fiber-liquor ratio was 1:50. Again the fiber was filtered and washed thoroughly with distilled water. The bleached okra bast fibre on the sintered funnel was then dried and preserved in a desicator.
For bleaching, about 1 gm dewaxed okra bast fibre dried at 105°C was treated with 0.7% sodium chlorite (NaClO2) solution buffered at pH 4. Required amount of sodium chlorite was dissolved in a known volume of water, and its pH, which was 10.6, was lowered to 4 by the gradual addition of 0.2N acetic acid. pH readings were taken with pH meter (Pocket). The pH meter was standardized with a buffer solution of known pH and was checked
with another buffer solution of known pH. A buffer mixture of pH 4 (acetic acid-sodium acetate) was prepared and added to the chlorite CH3COOH-CH3COONa buffer solution in the proportion of 1 ml of buffer solution for every 10 ml of chlorite solution, to ensure that pH remained at 4 throughout the progress of the reaction. This pH maintaining is necessary because many organic acids are liberated during bleaching and unless the mixture is buffered the pH of the medium would change. The bleaching process was carried out by digesting the fiber for about 2 h at 90-95°C. For each gram of the fiber 80 ml of the mixture was used. After bleaching the fibre was filtered over a sintered funnel and washed thoroughly with distilled water. It was then treated with 2% sodium metabisulphite solution for 15 min. The fiber-liquor ratio was 1:50. Again the fiber was filtered and washed thoroughly with distilled water. The bleached okra bast fibre on the sintered funnel was then dried and preserved in a desicator.
Scouring of Okra Bast Fiber
Scouring of Okra Bast Fibre
The removal of impurities such as dirty materials, fatty, waxy and gummy substances from textile materials is called scouring. It is carried out by the use of surface-active agents, such as soda and detergents.
About 30 cm from the bottom of the fibre was discarded and it was then cut into three equal parts (20 cm) viz. the top, the middle and the bottom. Middle portion of the fiber was used for investigation. Okra bast fibre was scoured in a solution containing 5 mg Na2CO3 and 5 gm detergent per liter of water in a large beaker. The ratio of the fiber to solution was 1:50. The solution with okra fibre was heated at 60°C for 30 min. Then the fiber was thoroughly washed with distilled water for several times. Finally it is dried at 80-90°C in an electric oven and stored in a desiccator.
The removal of impurities such as dirty materials, fatty, waxy and gummy substances from textile materials is called scouring. It is carried out by the use of surface-active agents, such as soda and detergents.
About 30 cm from the bottom of the fibre was discarded and it was then cut into three equal parts (20 cm) viz. the top, the middle and the bottom. Middle portion of the fiber was used for investigation. Okra bast fibre was scoured in a solution containing 5 mg Na2CO3 and 5 gm detergent per liter of water in a large beaker. The ratio of the fiber to solution was 1:50. The solution with okra fibre was heated at 60°C for 30 min. Then the fiber was thoroughly washed with distilled water for several times. Finally it is dried at 80-90°C in an electric oven and stored in a desiccator.
Collection and Preparation of Okra Fiber
Collection and Preparation of Okra Fibre
The okra fibre of different species are found in the various regions in Bangladesh. For our investigation the okra fiber was collected from Jhenidah district region. The plant is first retted into water for 13 to 15 days, the fibre was then separated from cementing and gummy materials. The fibre was washed in clean water for several times and dried in air without exposing sunlight. Finally the fibre was dried in an electric oven at 105°C and stored in a desicator.
The okra fibre of different species are found in the various regions in Bangladesh. For our investigation the okra fiber was collected from Jhenidah district region. The plant is first retted into water for 13 to 15 days, the fibre was then separated from cementing and gummy materials. The fibre was washed in clean water for several times and dried in air without exposing sunlight. Finally the fibre was dried in an electric oven at 105°C and stored in a desicator.
Sunday, June 26, 2011
My Investigation on Natural Okra Fiber
MY OF THE PRESENT INVESTIGATION
Okra bast fibre is a lignocellulosic fibre which contains higher percentage of α-cellulose. So it is indeed a very fascinating field of research with unlimited future possibilities for improving the desired properties of the fibre. They are generally biodegradable but do not possess the necessary and sufficent properties desirable for engineering or commodity plastics. Besides, like other vegetable fibres okra bast fibre possess few weak points i.e., rub resistance, colour fastness, wash and wear properties and very much prone to creasing, possibly because of high degree of orientation of cellulose in the fibre. This defect of creasing of cellulosic fiber may be remedied remarkably by the crease-resisting process in which resins are synthesized within the cellulosic materials in different proportions. In order to improve the textile properties of okra bast fibre it is an urgent need to improve several properties such as whiteness, softness, washing, dyeing behaviour, colour fastness, light resistance, thermal resistance, etc. So an attempt has been made to improve those characteristics of okra fiber through chemical modification and dyeing.
In the view of the above considerations, the following efforts have been exerted in the present investigation:
> To synthesize acrylonitrile resin onto okra bast fibre are focused on fiber-surface treatment methods and the resultant effects on the physical and mechanical properties of the fibre. The modification of okra bast fibre with acrylonitrile was carried out at varying initiator concentration, catalyst concentration, modification time, modification temperature.
> FTIR was employed to assess the relation between structure and properties after modification.
> SEM was used to observe the microstructure and the surface morphology of treated and untreated okra bast fibre.
> The bleached and modified okra bast fibres have been dyed with Direct Red 28 and Direct Green 27 in presence of sodium sulphate as an electrolyte. Electrolyte is used for obtaining better hue and level dyeing.
> The colour strength and CIE lab values of dyed samples are measured in Macbeth CE-3100 spectrophotometer.
> The colour fastness undyed and dyed (bleached and modified) okra bast fibre have been studied on the exposure to sunlight, wishing, acid spotting, alkali spotting and heat.
> The effect of various influences such as heat and light on tensile strength of bleached and modified okra bast fibre and their dyed fibre has been studied.
Okra bast fibre is a lignocellulosic fibre which contains higher percentage of α-cellulose. So it is indeed a very fascinating field of research with unlimited future possibilities for improving the desired properties of the fibre. They are generally biodegradable but do not possess the necessary and sufficent properties desirable for engineering or commodity plastics. Besides, like other vegetable fibres okra bast fibre possess few weak points i.e., rub resistance, colour fastness, wash and wear properties and very much prone to creasing, possibly because of high degree of orientation of cellulose in the fibre. This defect of creasing of cellulosic fiber may be remedied remarkably by the crease-resisting process in which resins are synthesized within the cellulosic materials in different proportions. In order to improve the textile properties of okra bast fibre it is an urgent need to improve several properties such as whiteness, softness, washing, dyeing behaviour, colour fastness, light resistance, thermal resistance, etc. So an attempt has been made to improve those characteristics of okra fiber through chemical modification and dyeing.
In the view of the above considerations, the following efforts have been exerted in the present investigation:
> To synthesize acrylonitrile resin onto okra bast fibre are focused on fiber-surface treatment methods and the resultant effects on the physical and mechanical properties of the fibre. The modification of okra bast fibre with acrylonitrile was carried out at varying initiator concentration, catalyst concentration, modification time, modification temperature.
> FTIR was employed to assess the relation between structure and properties after modification.
> SEM was used to observe the microstructure and the surface morphology of treated and untreated okra bast fibre.
> The bleached and modified okra bast fibres have been dyed with Direct Red 28 and Direct Green 27 in presence of sodium sulphate as an electrolyte. Electrolyte is used for obtaining better hue and level dyeing.
> The colour strength and CIE lab values of dyed samples are measured in Macbeth CE-3100 spectrophotometer.
> The colour fastness undyed and dyed (bleached and modified) okra bast fibre have been studied on the exposure to sunlight, wishing, acid spotting, alkali spotting and heat.
> The effect of various influences such as heat and light on tensile strength of bleached and modified okra bast fibre and their dyed fibre has been studied.
Moisture Absorption, Desorption and Swelling
Moisture Absorption, Desorption and Swelling
Moisture sorption is a physicochemical phenomenon. The hydroxyl groups of the carbohydrate fraction attract water molecules and attachment occurs due to hydrogen bonding. In a bone-dry fiber, water molecules can diffuse in to form such bonds ini-tially. Late-arriving molecules can attach themselves either to existing water molecules (indirect attachment) or to the other hydroxyl groups (direct attachment). Diffusion of water molecules does not take place in the crystalline regions of native cellulose in the fiber because of the relatively tight packing of the molecules therein. Thus, absorp¬tion of water is proportional to the extent of the fiber’s noncrystalline, less-oriented regions. Since hemicelluloses and polyuronides are not crystalline, their presence in the fiber will increase its regain. On the other hand, the presence of lignin decreases moisture absorption, since lignin is hydrophobic. In addition, layers of lignin in the inner middle lamella and close to the fiber surface will hinder penetration of moisture into the cellulosic cell wall.
According to Lewin, the small affinity of the lignin for moisture was, according to these investigators in accordance with the small changes in swelling behavior of the jute fiber after a considerable part of the lignin was removed. This is also the obvious explanation of the high moisture absorption in flax in spite of its well known high degree of crystallinity. If it is assumed that the regain of nonlignin middle lamella components in jute and flax is similar, it follows that, in the light of the much lower lignin content of flax, a higher regain should be expected for flax than jute. The lower crystallinity of a-cellulose in jute explains this discrepancy. It should be pointed out that the information on the contribution of the middle lamella and its constituents toward moisture absorption in bast and leaf fibers, other than flax and jute, is very scarce and limited.
Conventionally, the moisture sorption characteristics of fibers are depicted by ab-sorption/desorption isotherms. In practice, it is difficult to compare isotherms of dif-ferent fibers over the whole range of rh (relative humidity) and temperature values. It is often sufficient to compare their regains at the standard conditions of 65% rh and 21 °C (70°F). List gives absorption regains for a few fibers, together with the differences between absorption and desorption regains.
Fiber Absorption regain (%)
At 65% rh 700 F Difference between
desorption and absorption regains 65% rh 700 F
Abaca 9.5 --
Sisal 11.0 --
Cotton 7-8 0.9
Hemp 8 --
Jute 12 1.5
Kapok 10 --
Ramie (bleached) 6 --
Wool (scoured) 14 20
Coir 10 --
Banana 15.2 --
Okra Bast Fiber 9 1.2
Moisture sorption is a physicochemical phenomenon. The hydroxyl groups of the carbohydrate fraction attract water molecules and attachment occurs due to hydrogen bonding. In a bone-dry fiber, water molecules can diffuse in to form such bonds ini-tially. Late-arriving molecules can attach themselves either to existing water molecules (indirect attachment) or to the other hydroxyl groups (direct attachment). Diffusion of water molecules does not take place in the crystalline regions of native cellulose in the fiber because of the relatively tight packing of the molecules therein. Thus, absorp¬tion of water is proportional to the extent of the fiber’s noncrystalline, less-oriented regions. Since hemicelluloses and polyuronides are not crystalline, their presence in the fiber will increase its regain. On the other hand, the presence of lignin decreases moisture absorption, since lignin is hydrophobic. In addition, layers of lignin in the inner middle lamella and close to the fiber surface will hinder penetration of moisture into the cellulosic cell wall.
According to Lewin, the small affinity of the lignin for moisture was, according to these investigators in accordance with the small changes in swelling behavior of the jute fiber after a considerable part of the lignin was removed. This is also the obvious explanation of the high moisture absorption in flax in spite of its well known high degree of crystallinity. If it is assumed that the regain of nonlignin middle lamella components in jute and flax is similar, it follows that, in the light of the much lower lignin content of flax, a higher regain should be expected for flax than jute. The lower crystallinity of a-cellulose in jute explains this discrepancy. It should be pointed out that the information on the contribution of the middle lamella and its constituents toward moisture absorption in bast and leaf fibers, other than flax and jute, is very scarce and limited.
Conventionally, the moisture sorption characteristics of fibers are depicted by ab-sorption/desorption isotherms. In practice, it is difficult to compare isotherms of dif-ferent fibers over the whole range of rh (relative humidity) and temperature values. It is often sufficient to compare their regains at the standard conditions of 65% rh and 21 °C (70°F). List gives absorption regains for a few fibers, together with the differences between absorption and desorption regains.
Fiber Absorption regain (%)
At 65% rh 700 F Difference between
desorption and absorption regains 65% rh 700 F
Abaca 9.5 --
Sisal 11.0 --
Cotton 7-8 0.9
Hemp 8 --
Jute 12 1.5
Kapok 10 --
Ramie (bleached) 6 --
Wool (scoured) 14 20
Coir 10 --
Banana 15.2 --
Okra Bast Fiber 9 1.2
Auto-oxidation mechanism
Auto-oxidation mechanism
Degradation of polymers by chemical reactions is a typical consecutive property and chemical changes occur due to reaction with components in the environment. The most important of these degrading reagents is oxygen. Oxidation may be induced and accelerated by radiation (photo-oxidation) or by thermal energy (thermal oxidation). Thermal oxidation, like photo-oxidation is caused by auto-oxidation. In photochemical degradation the energy of activation is supplied by sunlight. In the most ordinary chemical reactions, the activation energy changes between 60 to 270 KJ/mol ranges. This is energetically equivalent to radiation of wavelengths between 1900 and 440 nm. Above room temperature, polymers degrade in air after an induction period by thermal aging.
Oxidation phenomenon of polymers was investigated very early in connection with the aging of natural rubber. Hofmann realized the connection between aging and the absorption of oxygen. Based on the fact that hydrocarbon compounds react with molecular oxygen forming oxidation products, the auto-oxidation developed by a free-radical chain reaction. Boland and Gee showed that the oxidation of hydrocarbons proceeds autocatalytically. The reaction is slow at the start, generally associated with shorter induction period. In this period, the polymer does not show any obvious changes and there is no evidence of oxygen absorption.
This period is nevertheless important in the process of polymer oxidation, because small amounts of hydroperoxides are formed which initiate the subsequent rapid auto-oxidation of the polymer. As a rule an increase in temperature reduces the induction period and accelerates the auto-oxidation. In some cases, when the polymer contains trace amounts of peroxide impurities or catalysts such as metallic salts, the induction period is not observed at all and the process of catalytic oxidation begins immediately. The decomposition of the hydroperoxides is commonly recognized as the process for the further rapid oxidation. The free-radical initiated chain reaction of auto-oxidation is depicted schematically in Figure . The radical processes during the thermal or photo-degradation of polypropylenes are identical. The basic oxidation mechanism has generally been believed to consist of the following three steps:
(i) Initiation:
RH > R.
(ii) PropagatioO2n:
R. + O2 > ROO.
(Peroxy radical)
This reaction is very fast and quickly converted into-
ROO. + RH > R. + ROOH
ROOH is very important species (unstable) which is responsible for degradation.
Chain branching:
ROOH > RO. + .OH
Termination:
2ROO. > ROOR + O2
Degradation of polymers by chemical reactions is a typical consecutive property and chemical changes occur due to reaction with components in the environment. The most important of these degrading reagents is oxygen. Oxidation may be induced and accelerated by radiation (photo-oxidation) or by thermal energy (thermal oxidation). Thermal oxidation, like photo-oxidation is caused by auto-oxidation. In photochemical degradation the energy of activation is supplied by sunlight. In the most ordinary chemical reactions, the activation energy changes between 60 to 270 KJ/mol ranges. This is energetically equivalent to radiation of wavelengths between 1900 and 440 nm. Above room temperature, polymers degrade in air after an induction period by thermal aging.
Oxidation phenomenon of polymers was investigated very early in connection with the aging of natural rubber. Hofmann realized the connection between aging and the absorption of oxygen. Based on the fact that hydrocarbon compounds react with molecular oxygen forming oxidation products, the auto-oxidation developed by a free-radical chain reaction. Boland and Gee showed that the oxidation of hydrocarbons proceeds autocatalytically. The reaction is slow at the start, generally associated with shorter induction period. In this period, the polymer does not show any obvious changes and there is no evidence of oxygen absorption.
This period is nevertheless important in the process of polymer oxidation, because small amounts of hydroperoxides are formed which initiate the subsequent rapid auto-oxidation of the polymer. As a rule an increase in temperature reduces the induction period and accelerates the auto-oxidation. In some cases, when the polymer contains trace amounts of peroxide impurities or catalysts such as metallic salts, the induction period is not observed at all and the process of catalytic oxidation begins immediately. The decomposition of the hydroperoxides is commonly recognized as the process for the further rapid oxidation. The free-radical initiated chain reaction of auto-oxidation is depicted schematically in Figure . The radical processes during the thermal or photo-degradation of polypropylenes are identical. The basic oxidation mechanism has generally been believed to consist of the following three steps:
(i) Initiation:
RH > R.
(ii) PropagatioO2n:
R. + O2 > ROO.
(Peroxy radical)
This reaction is very fast and quickly converted into-
ROO. + RH > R. + ROOH
ROOH is very important species (unstable) which is responsible for degradation.
Chain branching:
ROOH > RO. + .OH
Termination:
2ROO. > ROOR + O2
Degradation and Degrading Agents
DEGRADATION OF TEXTILE FIBRE
Concept of degradation
Polymer degradation involving light and heat is defined as a combination of chemical and physical changes occurring during the processing, storage and usage. This results in the loss of some useful properties of the polymeric material. These changes are mainly due to the competing chemical processes of macromolecular degradation and cross-linking. Polymer degradation and cross-linking involve a variety of conjugated chain-radical, ionic and molecular reactions.
The degradation reaction is broadly of two types: (1) Chain-end degradation and (2) random degradation. In the first type, the degradation starts from the chain-ends, resulting in a successive release of the monomeric units. This type of degradation is also called depolymerization (unzipping), the reverse of the propagation step in chain polymerization. The second type of degradation occurs at any random point along the polymer chain is called random degradation (zipping) which is the reverse of the polycondensation process. A distinguishing characteristic between the two types of degradation is that generally in the random process the molecular weight falls rapidly but considerably more slowly than in depolymerization.
Degrading agents
Types of degradation in the presence of various influences
Degrading Agents Types of degradation
1.Light (UV, visible) 1. Photochemical degradation
2. X-ray, gama-ray, fast electrous etc. 2. High energy radiation induced
degradation.
3. Laser light 3. Ablative photo degradation
4. Electrical field 4. Electrical Aging.
5. Plasma 5. corrosive degradation, etching.
6. Microorganism 6. Bio degradation.
7. Enzymes 7. Bio crosion.
8. Stress forces 8. Mechanical degradation
9. Ultra sound 9. Ultrasonic degradation
10. Chemicals (Acid, base etc.) 10. Chemical degradation
11. Heat 11. Thermal degradation and/or
decomposition
12. Oxygen, Ozone 12. Oxidative degradation (oxidation),
ozonolysis
13. Heat and oxygen 13. Thermoxidative degradation and/or
decomposition combustion
14. Light and O2 14. Photo oxidation
Concept of degradation
Polymer degradation involving light and heat is defined as a combination of chemical and physical changes occurring during the processing, storage and usage. This results in the loss of some useful properties of the polymeric material. These changes are mainly due to the competing chemical processes of macromolecular degradation and cross-linking. Polymer degradation and cross-linking involve a variety of conjugated chain-radical, ionic and molecular reactions.
The degradation reaction is broadly of two types: (1) Chain-end degradation and (2) random degradation. In the first type, the degradation starts from the chain-ends, resulting in a successive release of the monomeric units. This type of degradation is also called depolymerization (unzipping), the reverse of the propagation step in chain polymerization. The second type of degradation occurs at any random point along the polymer chain is called random degradation (zipping) which is the reverse of the polycondensation process. A distinguishing characteristic between the two types of degradation is that generally in the random process the molecular weight falls rapidly but considerably more slowly than in depolymerization.
Degrading agents
Types of degradation in the presence of various influences
Degrading Agents Types of degradation
1.Light (UV, visible) 1. Photochemical degradation
2. X-ray, gama-ray, fast electrous etc. 2. High energy radiation induced
degradation.
3. Laser light 3. Ablative photo degradation
4. Electrical field 4. Electrical Aging.
5. Plasma 5. corrosive degradation, etching.
6. Microorganism 6. Bio degradation.
7. Enzymes 7. Bio crosion.
8. Stress forces 8. Mechanical degradation
9. Ultra sound 9. Ultrasonic degradation
10. Chemicals (Acid, base etc.) 10. Chemical degradation
11. Heat 11. Thermal degradation and/or
decomposition
12. Oxygen, Ozone 12. Oxidative degradation (oxidation),
ozonolysis
13. Heat and oxygen 13. Thermoxidative degradation and/or
decomposition combustion
14. Light and O2 14. Photo oxidation
General Theory of Dyeing
The General Theory of Dyeing
Dyeing is the process of coloring textile materials by immersing them in an aqueous solution of dye, called dye liquor. Normally the dye liquor consists of dye, water and an auxiliary. To improve the effectiveness of dyeing, heat is usually applied to the dye liquor. The theory of aqueous dyeing, as explained below, is modified when an organic solvent is substituted for water. The general theory of dyeing explains the interaction between dyes, fiber, water and dye auxiliary. More specifically, it explains:
Forces of repulsion which are developed between the dye molecules and water. Forces of attraction which are development between the dye molecules and fibers.
These forces are responsible for the dye molecules leaving the aqueous dye liquor and entering and attaching themselves to the polymers of the fiber.
Dye molecules are organic molecules which can be classified according to the causing part of the color are listed bellow:
i) Anionic: In which the color is caused by the anionic part of the dye molecule.
ii) Cationic: In which the color is caused by the cationic part of the dye molecule.
iii) Disperse: In which the color is caused by the whole molecule.
Dyeing is the process of coloring textile materials by immersing them in an aqueous solution of dye, called dye liquor. Normally the dye liquor consists of dye, water and an auxiliary. To improve the effectiveness of dyeing, heat is usually applied to the dye liquor. The theory of aqueous dyeing, as explained below, is modified when an organic solvent is substituted for water. The general theory of dyeing explains the interaction between dyes, fiber, water and dye auxiliary. More specifically, it explains:
Forces of repulsion which are developed between the dye molecules and water. Forces of attraction which are development between the dye molecules and fibers.
These forces are responsible for the dye molecules leaving the aqueous dye liquor and entering and attaching themselves to the polymers of the fiber.
Dye molecules are organic molecules which can be classified according to the causing part of the color are listed bellow:
i) Anionic: In which the color is caused by the anionic part of the dye molecule.
ii) Cationic: In which the color is caused by the cationic part of the dye molecule.
iii) Disperse: In which the color is caused by the whole molecule.
Why Okra Bast Fiber is Dyed
Why a (Okra Bast Fiber) textile fiber is dyed
A textile material is dyed generally in order to enhance its appearance by the attraction of hue. Textiles may also be dyed for other special purposes, not necessarily involving attractive hues, e.g. camouflage, identification etc. The color is expected to withstand those agencies (exposure to light, weather, moisture, washing etc) which is likely to meet in use to a reasonable degree. In other words, dyeing are expected to be fast to a dyed textiles is that the hue should be uniform over the whole. The satisfactory achievement of these three attributes correct hue, satisfactory fastness and uniformity of hue comprises the art of dyeing.
A textile material is dyed generally in order to enhance its appearance by the attraction of hue. Textiles may also be dyed for other special purposes, not necessarily involving attractive hues, e.g. camouflage, identification etc. The color is expected to withstand those agencies (exposure to light, weather, moisture, washing etc) which is likely to meet in use to a reasonable degree. In other words, dyeing are expected to be fast to a dyed textiles is that the hue should be uniform over the whole. The satisfactory achievement of these three attributes correct hue, satisfactory fastness and uniformity of hue comprises the art of dyeing.
Colour and Vision
Color and vision
The ordinary light is composed of electromagnetic radiation of varying wavelength. On the basis of wavelength of light, the electromagnetic radiation can be divided into three types which are as follows:
Range of wave length of light (˚A) Part of time
1000 – 4000 Ultraviolet
4000 – 7500 Visible part (White light)
7500 – 1000000 Infra – red
Since our eyes are sensitive only to the electromagnetic radiation of wavelengths 4000 – 7500 ˚A., it is this region which produces a definite color in a particular substance. The UV radiation (wave length more than 7500 A) are not visible to human eyes.
When white light falls on a substance the color is obtained in different ways as:
• When the white light is reflected completely the substance will appear white.
• When the white light is absorbed completely the substance will appear black.
• When all the wavelengths of white light is absorbed except one single narrow bond which is reflected. Then the color of the substance will correspond to the color of the reflected band of light.
• When only a single bond of white light is absorbed the substance will have the complimentary color of the absorbed band of the light e.g. If the color absorbed lies in the range 4000 – 4350˚A. Then the color absorbed is violet and so the complementary color obtained will be yellow green.
The ordinary light is composed of electromagnetic radiation of varying wavelength. On the basis of wavelength of light, the electromagnetic radiation can be divided into three types which are as follows:
Range of wave length of light (˚A) Part of time
1000 – 4000 Ultraviolet
4000 – 7500 Visible part (White light)
7500 – 1000000 Infra – red
Since our eyes are sensitive only to the electromagnetic radiation of wavelengths 4000 – 7500 ˚A., it is this region which produces a definite color in a particular substance. The UV radiation (wave length more than 7500 A) are not visible to human eyes.
When white light falls on a substance the color is obtained in different ways as:
• When the white light is reflected completely the substance will appear white.
• When the white light is absorbed completely the substance will appear black.
• When all the wavelengths of white light is absorbed except one single narrow bond which is reflected. Then the color of the substance will correspond to the color of the reflected band of light.
• When only a single bond of white light is absorbed the substance will have the complimentary color of the absorbed band of the light e.g. If the color absorbed lies in the range 4000 – 4350˚A. Then the color absorbed is violet and so the complementary color obtained will be yellow green.
Requirements of True Dye
Requirements of True Dye
For a substance to act as a dye certain conditions must be fulfilled and these are as follows.
• It must have a suitable color
• It must have an attractive color
• It must be able to fix itself or be capable of being fixed to the fabric
• The substrate to be dyed must have affinity for an appropriate dye and must be able to absorb it from solution or aqueous dispersion, if necessary in the presence of auxiliary substances under suitable conditions of concentration, temperature and pH
• It must be soluble in water or must form a stable and good dispersion in water. Alternatively, it must be soluble in the medium other than water. However, it is to be remembered that the pick up of the dye from the medium should be good.
The fixed dye must have fastness properties, e.g.,
• Fastness to light,
• Fastness to temperature,
• Resistance to the action of water, dilute acids, alkalis and various organic solvents and soap solution.
For a substance to act as a dye certain conditions must be fulfilled and these are as follows.
• It must have a suitable color
• It must have an attractive color
• It must be able to fix itself or be capable of being fixed to the fabric
• The substrate to be dyed must have affinity for an appropriate dye and must be able to absorb it from solution or aqueous dispersion, if necessary in the presence of auxiliary substances under suitable conditions of concentration, temperature and pH
• It must be soluble in water or must form a stable and good dispersion in water. Alternatively, it must be soluble in the medium other than water. However, it is to be remembered that the pick up of the dye from the medium should be good.
The fixed dye must have fastness properties, e.g.,
• Fastness to light,
• Fastness to temperature,
• Resistance to the action of water, dilute acids, alkalis and various organic solvents and soap solution.
Dyeing and Dyes
Dyeing
The most important view of dyeing is for colouring textile material. Other than textiles there are other materials that are coloured by dyeing viz. paper products, leather products, cosmetics, foods etc. The dyeing usually is done to make the product attractive. Dyeing of textile materials is a process of applying a dye so that the materials not only change their color but also lastly retain the dye. The process that results in the materials acquiring one color is called plain dyeing or simply dyeing; the application of color to the material at separate places or of several colors forming a design is called pattern printing. The subject of dyeing includes two objects: the dyestuffs and the fiber and relation between them at certain conditions.
Dyes
Generally, a dye may be defined as a color substance which when applied to the fabrics a permanent color and the color is not usually removed by washing with water, soap or no exposure to sunlight. In other words, compounds containing charomophore and auxochrome groups are called dyes. Chromophore group is responsible for dye colour due to their unsaturation or multiple bonds e.g. --NO2, – N=O, --N = N--, quinonoid structure, >C = O etc.
Auxochrome group is responsible for dye fiber reaction e.g –OH, COOH, SO3H, –NH2, Cl- etc.
All colored substances are not necessarily dyes. For example, though both picric acid and trinitrotoluene are yellow in color but only picric acid can fix to a cloth where trinitrotoluene does no fix to a cloth and so it is not a dye.
Direct dyes
The characteristic features of direct dyes are:
(1) The shapes are long, narrow and flat
(2) The constitutive groups are -OH, -NH2 , -N=N– which may form hydrogen bond with --OH groups of the cellulosic chain and
(3) Two or more ion forming groups usually SO3Na which help the dissolution of dyes in water.
Direct dyes are used to dye animal fibers as well as cotton or the vegetable fibers without mordant directly. Some of them are also employed for dyeing union goods (cotton and wool or cotton and silk). These dyes are also called salt dyes, because of the fact that dyeing is usually carried out in presence of common salt or Glauber’s salt to the dye bath. The dye is applied to the fabric by immersing the fabric in hot boiling solution and then removing and drying the fiber. Addition of common salt increases the solubility of the dye and hence cause better exhaustion of it forms the dyeing solution.
The most important view of dyeing is for colouring textile material. Other than textiles there are other materials that are coloured by dyeing viz. paper products, leather products, cosmetics, foods etc. The dyeing usually is done to make the product attractive. Dyeing of textile materials is a process of applying a dye so that the materials not only change their color but also lastly retain the dye. The process that results in the materials acquiring one color is called plain dyeing or simply dyeing; the application of color to the material at separate places or of several colors forming a design is called pattern printing. The subject of dyeing includes two objects: the dyestuffs and the fiber and relation between them at certain conditions.
Dyes
Generally, a dye may be defined as a color substance which when applied to the fabrics a permanent color and the color is not usually removed by washing with water, soap or no exposure to sunlight. In other words, compounds containing charomophore and auxochrome groups are called dyes. Chromophore group is responsible for dye colour due to their unsaturation or multiple bonds e.g. --NO2, – N=O, --N = N--, quinonoid structure, >C = O etc.
Auxochrome group is responsible for dye fiber reaction e.g –OH, COOH, SO3H, –NH2, Cl- etc.
All colored substances are not necessarily dyes. For example, though both picric acid and trinitrotoluene are yellow in color but only picric acid can fix to a cloth where trinitrotoluene does no fix to a cloth and so it is not a dye.
Direct dyes
The characteristic features of direct dyes are:
(1) The shapes are long, narrow and flat
(2) The constitutive groups are -OH, -NH2 , -N=N– which may form hydrogen bond with --OH groups of the cellulosic chain and
(3) Two or more ion forming groups usually SO3Na which help the dissolution of dyes in water.
Direct dyes are used to dye animal fibers as well as cotton or the vegetable fibers without mordant directly. Some of them are also employed for dyeing union goods (cotton and wool or cotton and silk). These dyes are also called salt dyes, because of the fact that dyeing is usually carried out in presence of common salt or Glauber’s salt to the dye bath. The dye is applied to the fabric by immersing the fabric in hot boiling solution and then removing and drying the fiber. Addition of common salt increases the solubility of the dye and hence cause better exhaustion of it forms the dyeing solution.
Monomer, Initiator and Catalyst
MONOMER
Low molecular weight compounds having a functionality of two or more from which polymers are formed are called monomers. To polymerise them, it only renders a suitable reaction conditions. Then, these monomer molecules add each other to form fewer but higher molecular weight compound.
The functionality of a monomer depends on the number of reactive sites it has. A compound assumes functionality because of the presence of reactive functional groups like -OH, -COOH, - NH2 etc. The number of functional groups per molecule of the compound defines its functionality.
Some compounds which do not contain any reactive functional group but the presence of double or triple bonds in molecule bestows poly-functionality on them are called vinyl monomers. For example, ethylene which can take on two atoms of hydrogen, because of the presence of a double bond and hence, functionality two.
CH2=CH2 + H2 = CH3-CH3
Similar is the ease with other homologous of ethylene and vinyl compounds such as methacrylic acid [H2C=C(CH3)COOH], acrylamide [H2C=CH-CONll2], methyl methacrylate [H2C=C(CH3)COOCH3], methyl acrylate [H2C=CHCOOCH3], acrylonitrile [CH2=CH-CN], etc. Acetylene has a functionality of four i.e. [HC CH].
There are some other compounds in which the presence of easily replaceable hydrogen atoms contributes functionality. Phenol is an example of such type.
INITIATIOR
The initiation reaction of polymerisation is carried out by initiators. Initiators are thermally unstable compounds and decompose into products called free radicals. These free radicals can attack monomers and initiate the polymerisation reaction.
If R- R is an initiator and the pair of electrons forming the bond between two ‘R’ can be represented by dots, the initiator can be written as R:R. Initiators are decomposed by homolytic dissociation and are splited into two symmetrical components. Each component carries with it one of the electrons from the electron pair, is called free-radieal, i.e. R – R 2R•. The decomposition of the initiator to form free radicals can be introduced by heat energy, light, catalyst etc. Potassium persulphate (K2S2O8), azo compounds, peroxides, hydroxides, peracids and peresters are useful initiators.
CATALYST
The catalyst may be responsible for peculiar chain initiation and possess a metal atom with some + ionic character. The reason for their presence varies from reaction to reaction. For instance, in the vinyl type reactions, the catalysis are required to produce initiating centres. Many metallic salts such as FeSO4, FeCl3, Fe2(SO4)3, CuSO4, ZnSO4, K2SO4, CoSO4 , H2SO4 etc. are used as catalyst for graft copolymerisation of cellulosic materials.
Low molecular weight compounds having a functionality of two or more from which polymers are formed are called monomers. To polymerise them, it only renders a suitable reaction conditions. Then, these monomer molecules add each other to form fewer but higher molecular weight compound.
The functionality of a monomer depends on the number of reactive sites it has. A compound assumes functionality because of the presence of reactive functional groups like -OH, -COOH, - NH2 etc. The number of functional groups per molecule of the compound defines its functionality.
Some compounds which do not contain any reactive functional group but the presence of double or triple bonds in molecule bestows poly-functionality on them are called vinyl monomers. For example, ethylene which can take on two atoms of hydrogen, because of the presence of a double bond and hence, functionality two.
CH2=CH2 + H2 = CH3-CH3
Similar is the ease with other homologous of ethylene and vinyl compounds such as methacrylic acid [H2C=C(CH3)COOH], acrylamide [H2C=CH-CONll2], methyl methacrylate [H2C=C(CH3)COOCH3], methyl acrylate [H2C=CHCOOCH3], acrylonitrile [CH2=CH-CN], etc. Acetylene has a functionality of four i.e. [HC CH].
There are some other compounds in which the presence of easily replaceable hydrogen atoms contributes functionality. Phenol is an example of such type.
INITIATIOR
The initiation reaction of polymerisation is carried out by initiators. Initiators are thermally unstable compounds and decompose into products called free radicals. These free radicals can attack monomers and initiate the polymerisation reaction.
If R- R is an initiator and the pair of electrons forming the bond between two ‘R’ can be represented by dots, the initiator can be written as R:R. Initiators are decomposed by homolytic dissociation and are splited into two symmetrical components. Each component carries with it one of the electrons from the electron pair, is called free-radieal, i.e. R – R 2R•. The decomposition of the initiator to form free radicals can be introduced by heat energy, light, catalyst etc. Potassium persulphate (K2S2O8), azo compounds, peroxides, hydroxides, peracids and peresters are useful initiators.
CATALYST
The catalyst may be responsible for peculiar chain initiation and possess a metal atom with some + ionic character. The reason for their presence varies from reaction to reaction. For instance, in the vinyl type reactions, the catalysis are required to produce initiating centres. Many metallic salts such as FeSO4, FeCl3, Fe2(SO4)3, CuSO4, ZnSO4, K2SO4, CoSO4 , H2SO4 etc. are used as catalyst for graft copolymerisation of cellulosic materials.
Grafting Sites on the Cellulose and Mechanism for Okra Bast Fiber
GRAFTING SITES ON THE CELLULOSE AND MECHANISM
Okra bast basically is a cellulosic fibre. The structural unit of cellulose is C6H10O5 or anhydroglucose unit. In the presence of monomer, chain radicals such as (I), (II) and (III) load to graft copolymers, whereas (IV), (V) will give rise to block copolymers.
Actually both types of reactions are found to take place. In addition there will be radicals formed by radiolysis of the monomer and if there is a solvent present by radiolysis of the solvent, these monomer and solvent radicals lead to formation of homopolymer.
Cellulose is not simply possible to modified the properties owing to the fact that the cellulose chains become part of a three dimensions network, the material becomes harder and more rigid.
Grafting onto cellulose is therefore of necessity a heterogeneous reaction in which the physical structures and states of aggregation of the cellulose plays a significant role. The synthesis of cellulose graft copolymer differs from the fully synthetic graft copolymer by the fact that cellulose insoluble in all common organic solvents. Okra bast cellulose is a naturally occurring polymer which is not simply possible to modify in its properties. However, since the greatest number of synthesis involved heterogeneous grafting reactions these will form the first and most important part of the discussion of grafting methods. The polymerization of vinyl monomers may be initiated by free radicals or by certain ions. Free radicals can be generated on a cellulose chain by hydrogen abstraction oxidation, ceric-ion method, diazotisation and introduction of unsaturated groups or by irradiation. If a vinyl monomer is polymerized in the presence of cellulose by a free radical process, a hydrogen atom may be abstracted from the cellulose by growing chain radical or by a radical formed by the polymerization catalyst. This leads to an unshared electron on the cellulosic chain is capable of grafting.
It should be pointed out here that cellulose is a very poor transfer agent (1) and that very little graft copolymer results from the abstraction of hydrogen atoms by a growing chain radical. In most cases it is not the growing chain radical but a radical produced by the initiator which is responsible for formation of graft copolymer.
Thus in case of redox initiation with potassium persulphate (K2S2O8) and ferrous sulphate (FeSO4), •OH free radicals are generated which abstracts a hydrogen atom from the cellulose and thereby leads to grafting.
1 i) K2 S2O8 = 2K+ + S2 O8=
ii) FeSO4 = Fe++ + SO4=
2 i) S2 O8= + Fe (II) Adduct
ii) Adduct Fe (III) + 2SO4-
3 i) Fe (III) + H2O Fe (II) + + H+ HO.
ii) SO4- + H2O SO=4 + + H+
Okra bast basically is a cellulosic fibre. The structural unit of cellulose is C6H10O5 or anhydroglucose unit. In the presence of monomer, chain radicals such as (I), (II) and (III) load to graft copolymers, whereas (IV), (V) will give rise to block copolymers.
Actually both types of reactions are found to take place. In addition there will be radicals formed by radiolysis of the monomer and if there is a solvent present by radiolysis of the solvent, these monomer and solvent radicals lead to formation of homopolymer.
Cellulose is not simply possible to modified the properties owing to the fact that the cellulose chains become part of a three dimensions network, the material becomes harder and more rigid.
Grafting onto cellulose is therefore of necessity a heterogeneous reaction in which the physical structures and states of aggregation of the cellulose plays a significant role. The synthesis of cellulose graft copolymer differs from the fully synthetic graft copolymer by the fact that cellulose insoluble in all common organic solvents. Okra bast cellulose is a naturally occurring polymer which is not simply possible to modify in its properties. However, since the greatest number of synthesis involved heterogeneous grafting reactions these will form the first and most important part of the discussion of grafting methods. The polymerization of vinyl monomers may be initiated by free radicals or by certain ions. Free radicals can be generated on a cellulose chain by hydrogen abstraction oxidation, ceric-ion method, diazotisation and introduction of unsaturated groups or by irradiation. If a vinyl monomer is polymerized in the presence of cellulose by a free radical process, a hydrogen atom may be abstracted from the cellulose by growing chain radical or by a radical formed by the polymerization catalyst. This leads to an unshared electron on the cellulosic chain is capable of grafting.
It should be pointed out here that cellulose is a very poor transfer agent (1) and that very little graft copolymer results from the abstraction of hydrogen atoms by a growing chain radical. In most cases it is not the growing chain radical but a radical produced by the initiator which is responsible for formation of graft copolymer.
Thus in case of redox initiation with potassium persulphate (K2S2O8) and ferrous sulphate (FeSO4), •OH free radicals are generated which abstracts a hydrogen atom from the cellulose and thereby leads to grafting.
1 i) K2 S2O8 = 2K+ + S2 O8=
ii) FeSO4 = Fe++ + SO4=
2 i) S2 O8= + Fe (II) Adduct
ii) Adduct Fe (III) + 2SO4-
3 i) Fe (III) + H2O Fe (II) + + H+ HO.
ii) SO4- + H2O SO=4 + + H+
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