Environmental chemistry

Dr. SURENDRAN PARAMBADATH (M.Sc, M.Phil, M.Tech)

Formerly: Post Doctoral Research Associate,Nano-Information Materials Research Laboratory,

Pusan National University, Busan-South Korea

Currently: Assistant ProfessorGovt. Polytechnic College, Perinthalmanna

Environmental Pollution

Air Pollution

Water Pollution

Soil Pollution

Voice or Sound Pollution

Thermal Pollution

Radioactive Pollution

Pollution: It is defined as the consequence of excessive discharge or addition of unwanted constituents to the air, water or land, which adversely change the quality of environment.

Pollutant: The substances which will cause pollution is called pollutant.

Categorization of Pollution

The subject of pollution is broadly classified in to, 1.Air Pollution2.Water Pollution3.Land or soil Pollution4.Noise pollution5.Thermal Pollution6.Radioactive pollution

Air PollutionIt is the excessive discharge of undesired foreign substances into the atmospheric air.

1) Primary Pollutants: Theses are harmful chemical substances that directly enter the air as a result of natural events and human activities.

Carbon Monoxide, Carbon dioxide, Nitrogen oxide, Sulphur oxide, Hydrogen sulphide, Ammonia

2) Secondary Pollutants: Theses are harmful chemicals formed in the air due to a chemical reaction between two or more components or primary pollutants and one or more air components.

SO2, NO2, O3, Aldehydes, Ketones etc…

Sources of air Pollutants

1) Chemical industries and thermal power stations

2) Automobiles3) Domestic and other sources.

Control of air pollutionA. Reduction of contaminates from the source

1 Use appropriate materials or suitably change the raw materials

2 Select proper site for industrial units, far away from residential area,

3 Prevent or lessen, as far as possible, the smoke emitted during combustion of fuel by, correct method, admitting correct quantities of air, maintaining high temperature for complete combustion and feeding the fuel continuously.

4 Use catalytic converters to eliminate pollutants from exhaust gases before discharging in to the atmosphere.

5 Pass gases or vapors through towers packed with coke to remove chemicals and acid fumes, while applying a counter current of water from the top.

6 Grow more trees to increase photosynthesis rate and for better deposition of particulates.

B. Reduction of contaminants by modification

1 Modifications of internal combustion engines to reduce the amount of pollutants, with better design, suitable catalysts in the fuel, mixing and burning exhaust gases with more air and improving the quality of gasoline.

2 Developing substitute fuel to lower concentration of pollutants

3 Using alternative power sources, such as electricity, nuclear power geothermal power and solar power for domestic and industrial purposes.

Green House Effect

The heating of the earth due to trapped radiations is called Green House Effect or Global Warming. Green house gases: CO2, CFC, Water vapor, Methane, Ozone, Nitrogen Oxide etc.

Heat re-emitted by earth and absorbed by gases Heat radiated

back to earth

Implication of Green House Effect

1 Summer will be longer and hotter. Winter will be shorter and warmer.

2 Total amount of global rainfall will increase but some region will receive less rainfall.

3 The number of days having intense shower and high temperature both will increase.

4 The problem of desertification, drought and soil erosion will become more worse.

5 Ocean will get warm up, sea level would rise flooding low lying regions.

6 Increase in green house effect will cause cooling of the stratosphere.

7 Tropical storms, hurricanes will be stronger and more frequent and cause devastation

8 Tropics may become wetter, and dry subtropics drier.

Photochemical SmogSmoke + Fog = Smog

There are two types of smog:1) Chemical Smog: It is formed by condensation of smoke dust

particles and fog containing SO2 from polluted air.

2) Photochemical smog: It is formed by the combustion of smoke dust particles and fog containing the secondary air pollutants resulting from a series of photochemical reactions between NO, O2, H2O with hydrocarbons from exhaust, under the influence of sunlight.

Harmful effect of photochemical Smog

It causes irritation to eyes, nose and throat, leading to several chronic diseases of eyes. The O3 and PAN composites are toxic and affect the respiratory tract and result in coughing, sneezing and bronchial constrictions. It affects human comfort and health.It damages vegetation, affect plant growth, and reduce crop production. PAN attacks younger leaves and causes bronzing and glazing of their surfaces. Ozone attacks rubber, cracks it and makes it aged.

Acid rain means the presence of excessive acid in rain water.

Acid rain is a mixture of the acids HNO3 and H2SO4 dissolved in water.

The oxides (SO2 and NO2 are highly water soluble and under humid conditions of air react with water vapour to form H2SO4 and HNO3. These acids combine with HCl generates acid precipitation which is commonly known as acid rain.

Acid Rain

Harmful effect of Acid Rain

1. Causes irritation to the eyes and mucus membrane dangerous ti living organisms as it can destroy life.

2. Causes damage of fresh water life.3. In mist form, it causes direct damage to plant

leaves, leaf bleaching. Collapse of leaves and narcosis.

4. Animals consuming vegetation affected by acid rains, lose their hunger.

5. Presence of acid accelerates the rate of corrosion of metals, causes damage to buildings, statues, lime stone, marbles etc.

Ozone Layer Depletion of ozone and consequences

Ozone is formed by the decomposition of atmospheric oxygen by UV radiation from the sun.

1.This may be due to natural process. The N2O in the stratosphere can remove excited oxygen atoms required for formation of O3.

2.Freons, ie Chlorofluoro compounds CFCl3, CFCl2 and CFCl etc. have certain special properties and are used as industrial solvents, refrigerants, fast food packing materials, plastic foams etc. At stratosphere theses undergo photolysis into chlorine atoms which act upon ozone and destroy it.

Consequences of Ozone depletion

1.Most important consequence is the serious threat to mankind resulting in skin cancer, due to exposure to sun’s UV rays which freely reach the earth.

2.UV rays may damage immune system which may lead to increased viral infection.

3.UV radiations will damage marine plants, marine animals and fish which form an important part of human food.

4.These may damage the land’s plants and crops.

5.Excess unused freons trap the warmth of the sun, disturb green house effect, leading to high temperature, which could further damage crops and by increased melting of ice, pose dangers to low lying ocean port cities.

REMEDY

1.Control the production and use of freons which are proved to be harmful to ozone.

2.Replace freons by compounds having their advantageous properties, but with a lesser destructive effect.

Water Pollution

Water pollution may be defined as any change in the physical, chemical and biological properties of water as well as contamination with any foreign substance.

Sources of Water Pollution1. Faulty sewage system:

2. Agriculture wastes:

3. Oil Pollution:

4. Industrial effluents:

Effect of Impurities in Water1. Presence of disease causing bacteria result in

several water borne diseases. Typhoid fever, cholera, viral fever, bacterial fever etc.

2. Industrial waste lead to damage of property through corrosive attack.

3. Pollution of natural water due to organic waste, under the influenec of bacterial action, reduce the dissolved oxygen content in water.

4. Presence of agricultural waste such as pesticides, weedicides, herbicides as well detergents and disinfectants and other toxic substances kill animals and micro organisms.

5. Polluted water affects soil fertility by killing soil microorganisms.

6. Presence of heavy metals, like Hg, Cr, Pb, Cu, Zn etc. are toxic to animals and plants and micro organisms.

7. Suspended solid, coloring matter, floated oils and greases make water unsuitable for use.

8. Radioactive waste released into water, without proper pre-treatment causes health harzards in several ways.

Control of Water Pollution1.Control over unhygienic practices. Educate peoples, Dispose waste water properly, control usage of insecticides.2. Industrial WasteDispose waste safely.3. Heavy metal removalDialysis, ion exchange, reverse osmosis,chemical precipitation, adsorption.4. Sewage treatmentPurify properly.

Sewage Water TreatmentIt aims the transfer of harmful compounds in the sewage to harmless compounds, before its ultimate disposal either on land or dilution in water.

Three stages of this process are,1. Primary or mechanical treatment2. Secondary or biological treatment3. Tertiary or advanced biological, physical and

chemical treatment.

1. Primary TreatmentA. Preliminary Process: It involves the

removal of large, coarse, inorganic, suspended or floating materials. The sewage is passed through bar screens and mesh screens.

B. Settling Process: It removes greater proportions of the suspended inorganic and organic solids from the liquid sewage.

The sewage water from the sedimentation tank is further oxidized by aerobic chemical oxidation or aeration.

Carbon-CO2N-NH3 initially and finally nitrites and nitrates.

2. Secondary Treatment

3.Tertiary TreatmentThis treatment is for further purification of waste water as well its recycling. The main function of this treatment is to decrease the load of nitrogen and phosphorous compounds in the effluents by,1.Precipitation: Effluent from secondary

treatment is mixed with lime CaO. With phosphorus compounds the lime turns to insoluble calcium phosphate, which settle down at the bottom and is filtered off.

2.Nitrogen stripping: The waste water is sent into a metal tower, in which water trickles downwards over a series of small plastic baffle plates. Air is forced upwards through the effluent and NH3 gas gets removed.

3. After removing the P, N and Organic matter, the effluent is chlorinated to kill disease-causing micro organism that may be presented in the waste water.

Soil or Land Pollution

It is the addition of certain chemical substances in an indefinite proportion to the soil system as a result of which the fertility of the soil change.

Impact of soil pollution

1. Improper disposal of human and animal excreta.2. Domestic and industrial waste dumped on land.3. Chemicals like fertilizers, pesticides applied to

plants and soil.4. Dumping of waste from mineral and coal mining

and metal smelting on land. 5. Soil erosion due to deforestation, over grazing,

unplanned irrigation and defective agriculture practice.

6. Removal of upper fertile layer of soil.7. Pollution from air and fall-out from smoke stacks

of chemical works. 8. Radioactive waste discharged from hospitals,

industrial and research centers.

Control of Soil Pollution

1.Unwanted waste to be dumped using sanitary land filling

2.Industrial and sewage waste to be properly treated before disposal on land.

3.Natural soil micro-organisms to be used to increase crop fertility rather than using fertilizers and insecticides.

4.Forestation.5.People should be trained regarding the

sanitation habit. 6.Avoid negligent disposal of solid waste. 7.Ban toxic chemicals and pesticides.

Noise PollutionIt is a kind of pollution caused by unwanted noise at a wrong time and a wrong place naturally or artificially, which will be uncomfortable for health.

Impact of Noise Pollution

1. It affects human health, comfort and efficiency, contract blood vessels and increase blood pressure.

2. Cause muscles to contract, leading to nervous break down, tension and even insanity.

3. The most immediate and acute effect is impact of hearing or even loss of hearing.

4. It affect efficiency and behavior, can cause damage to heart, brain etc.

5. It may be a reason for diseases like eosnophelia etc.

Prevention of Noise pollution

1. Industrial Noise: Industries should be situated far away from cities or towns. Cover noise producing machineries with insulators. Properly maintain machineries2. Community noise control: Use cotton plugs or ear muffles.

Thermal Pollution

Thermal pollution may be defined as addition of undesirable heat to water, that makes it harmful to man, animal or aquatic life.

Radioactive Pollution

Hazards of Nuclear Radiators

1.Pathological damage: Living organisms are damaged by the highly penetrating radioactive radiations.

2.Genetic Effects: Transmitted to future generations producing abnormalities in the offsprings which may be mild or deadly.

3.Nuclear radiations: It may reduce the effectiveness of enzymes and cause accumulation of certain dangerous elements in certain specific organs or tissue.

GREEN CHEMISTRY

The chemistry aims the use of environmentally friendly materials for chemical or biological transformation.

Green Chemistry is in Action

1.Using CO2 and a detergent for dry cleaning instead of carcinogenic tetrachloroethane

2.Using H2O2 for bleaching of cloths in laundry instead of toxic chlorine.

3.Using H2O2 for bleaching paper in the place of toxic chlorine.

Keep Our Nature Beautifully…..

Love our hereditary…………

Observe Our Nature More and More

It is Very Beautiful

Get the Speech Between Sky and Land……

Find the Wild Beauty From Your Vicinity……..

Get The Magic & Wonder Creation of Nature

Find Beauty By Becoming Simple

Enjoy the painting of god

Thanks for Everything.....!