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Environmental Chemistry

Environmental Chemistry. What is environmental chemistry?. Study of Chemical species Origin Transport Reactions Effects Fate. MOST IMPORTANT ASPECT OF EN.CHEMISTRY. ENVIRONMENTAL POLLUTION. What Does It Mean?

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Environmental Chemistry

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  1. Environmental Chemistry Rimmy Augustine

  2. What is environmental chemistry? • Study of Chemical species • Origin • Transport • Reactions • Effects • Fate Rimmy Augustine

  3. MOST IMPORTANT ASPECT OF EN.CHEMISTRY ENVIRONMENTAL POLLUTION What Does It Mean? Introduction of pollutants into the environment that causes undesirable changes and has harmful effects on plants, animals, and human beings Rimmy Augustine

  4. Pollutants − Waste materials, which cause pollution 1.Biodegradable waste/pollutant − Breaks down easily Examples: food and garden waste, human waste, etc. 2.Non-biodegradable waste − Not easily degradable Examples: plastic, glass, heavy metals, etc. Rimmy Augustine

  5. ENVIRONMENTAL POLLUTION - TYPES • ATMOSPHERIC POLLUTION • SOIL POLLUTION • WATER POLLUTION Rimmy Augustine

  6. ATMOSPHERIC POLLUTION Atmosphere ? Rimmy Augustine

  7. ATMOSPHERIC POLLUTION- types Tropospheric pollution Stratospheric pollution Rimmy Augustine

  8. Tropospheric pollution • Gaseous air pollutants • Oxides of sulphur • Oxides of nitrogen • Oxides of carbon • hydrocarbons • Particulate pollutants • Smoke • Dust • Mists • Fumes Rimmy Augustine

  9. Oxides of sulphur Example: SO2 and SO3 • Formation: • burning S containing substances • Catalytic oxidation of SO2 to form SO3 Rimmy Augustine

  10. Harmful effects? • Irritation to throat and eyes • Asthma, bronchitis, respiratiory diseases • Damage to plants,loss of chlorophyll, stiffness of flower buds • Damage to buildings, (TajMahal) Sink/ control • Lime stone acts as a sink. It reacts with sulphuric acid • Remove sulphur from fuels • Use hydroelectric or nuclear power plants Rimmy Augustine

  11. Oxides of nitrogen Example: NO(nitric oxide) and NO2(nitrogen dioxide) • Formation: • during lightning strikes • Nitric oxide reacts with ozone Rimmy Augustine

  12. Harmful effects? • Irritant red haze in traffic • Asthma, bronchitis, respiratory diseases • Damage to plants, retard photosynthesis • Harmful for fibres and metals Sink/ control • Gases get converted to nitric acid • Removed from atmosphere by acid rain Rimmy Augustine

  13. Oxides of carbon Example: CO and CO2 • Formation: CO • incomplete combustion of carbon or fuel • Dissociation of CO2 at high temperature • Conversion of methane • Sink/ control • microorganisms present in soil convert CO to CO2 • Catalytic convertor fitted to exhaust pipes • Use CNG or LNG instead of petrol, diesel Rimmy Augustine

  14. Harmful effects? • Causes CO poisoning • Form carboxy haemoglobin • 300 time more stable than oxy haemoglobin • Loses capacity to carry oxygen • Leads to cardio vascular disorder • Causes anoxia(acute oxygen starvation) Rimmy Augustine

  15. Formation: CO2 • respiration • Burning of fuel • Decomposition of carbonate salts • Sink/ control • green plants • Control burning substances Rimmy Augustine

  16. Green house effect Atmosphere traps the sun’s heat near the earth’s surface and keeps it warm. It is called green house effect GLOBAL WARMING Carbon dioxide also trap heat. If the amount of carbon dioxide crosses the delicate proportion of 0.03 per cent, the natural green house balance may get disturbed and lead to global warming. Green house gases Carbon dioxide, methane, water vapour, nitrous oxide, CFCs, and ozone. ANIMATION Rimmy Augustine

  17. Assignment • What is acid rain? • How is it caused? • What are its harmful effects? • How to control it • TWO A4 SIZE PAGES ANIMATION ACID RAIN Rimmy Augustine

  18. PARTICULATE POLLUTANTS Small solid particles and liquid droplets suspended in air are collectively called as particulate pollutants Viable particulates Non viable particulates Rimmy Augustine

  19. VIABLE PARTICULATES Viable particulates are minute living organisms that are dispersed in atmosphere. Bacteria, Fungi, moulds etc. Rimmy Augustine

  20. NON - VIABLE PARTICULATES 1. SMOKE: Solid carbon particles formed during combustion 2. DUST: Solid particles formed during crushing and grinding 3. MIST: Particles of spray liquid and condensation of vapours in the air 4. FUMES: vapours of certain material present in air Rimmy Augustine

  21. HARMFUL EFFECTS OF PARTICULATES Particulates entering the lungs causes cancer, asthma, bronchitis etc Lead particulates causes retarded memory It retards photosynthesis in plants Leads to poor visibility in roads Rimmy Augustine

  22. SMOG (Smoke + Fog) • London smog/ Classical smog/reducing smog • It killed many people in London • Occurs in cool humid conditions • Mixture of smoke, fog and sulphur dioxide • Due to presence of Carbon it is reducing in nature 1. LONDON SMOG Rimmy Augustine

  23. SMOG (Smoke + Fog) ANIMATION • B. Photochemical smog /Los Angeles smog/Oxidising smog • First observed in Los Angeles • Occurs in warm dry and sunny climate • In presence of sunlight NO2 and hydrocarbons gets converted to harmful products like PAN, aldehyde, ketone, ozone and nitric oxide. • Ozone and NO2 are oxidising in nature • HARMFUL EFFECTS • Powerful eye irritants • Causes headache chest pain cough • Extensive damage to plant life Rimmy Augustine

  24. Los Angels photochemical smog ANIMATION Rimmy Augustine

  25. CHEMISTRY OF PHOTOCHEMICAL SMOG 1. Sunlight breaks down NO2 to NO and oxygen free radical 2. Ozone is produced by the reaction between O and O2 O(g) + O2(g) O3(g) 3. Ozone forms more NO2 by reaction with NO Ozone initiates other free radical mechanisms to form PAN(Peroxy acetyl nitrate,aldehyde and ketone CH4(g) + O3(g) HCHO + CH2 = CH-CHO + CH3COOONO2 METHANAL ACROLEIN PAN Rimmy Augustine

  26. CONTROL OF PHOTOCHEMICAL SMOG • Catalytic converters in automobiles reduces NO2 and hydrocarbon • Certain plants like Pinus, Juniparus and Vitis metabolise nitrogen oxides PINUS JUNIPERS Vitis (grape wines) Rimmy Augustine

  27. GROUP A (601 -615)/ (644 -660)/(194-207) • WATER POLLUTION • Major water pollutants • Causes (1) pathogens (2) organic wastes stress on BOD • International standards for drinking water • GROUP B ( 616 – 630) /(661 – 675)/(208-220) • SOIL POLLUTION • Major Pollutants • Causes • Pesticides • Industrial waste • GROUP C ( 631 – 643) /(676 -687)/(221- 233) • Strategies to control environmental pollution • Waste management • Green chemistry Rimmy Augustine

  28. Stratospheric Pollution Ozone hole Rimmy Augustine

  29. Ozone Layer Rimmy Augustine

  30. Ozone Layer importance Rimmy Augustine

  31. If no Ozone layer??????? • More UV rays reaches earth • Ageing of skin • Skin cancer • Sun burn • cataract • Evaporation of surface water • Damage to phytoplankton and fishes Rimmy Augustine

  32. Ozone layer formation • UV rays split oxygen molecules into free oxygen atoms • Oxygen atoms combine with molecular oxygen to form ozone O(g) + O2(g) O3(g) • Ozone further absorbs UV rays and split into dioxygen and an oxygen atom. • A dynamic equilibrium exists between production and decomposition of ozone uv O3(g) O2(g)+ O(g) Rimmy Augustine

  33. Ozone layer depletion • CFCs from different sources reach the stratosphere • Powerful UV rays break them down to free radicals • Chlorine radical react with ozone to form O2 and chlorine monoxide • Chlorine monoxide produces more chlorine radicals by reacting with oxygen atoms • Process gets repeated leading to more break down of ozone ANIMATION Rimmy Augustine

  34. OZONE DEPLETION BY CHLORO FLUORO CARBONS Rimmy Augustine

  35. OZONE HOLE OVER SOUTH POLE Rimmy Augustine

  36. OZONE HOLE OVER SOUTH POLE Summer climate: - sink for chlorine free radical / less ozone depletion Nitrogen dioxide combines with chlorine monoxide to form chlorine nitrate which is non reactive. Methane combines with chlorine free radical to form methyl free radical and HCl. Chain reaction stops. Winter climate:- Polar stratospheric clouds(PSC)/ an initiator for depletion A. In presence of PSC chlorine nitrate gets hydrolysed to hypochlorous acid. B. In presence of PSC chlorine nitrate gets hydrolysed to Cl2 . Rimmy Augustine

  37. spring season:- Ozone depletion by chain reaction In sunlight HOCl and Cl2 are photolysed to free radicals causing ozone depletion Rimmy Augustine

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