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Chemistry and the Environment

Chemistry and the Environment. ~Pollution. Air pollution. Air pollutants. Sulphur Dioxide Nitrogen Dioxide (NO2) Carbon Monoxide Photochemical Oxidants Respirable Suspended Particulates Lead Ozone. Effects of Polluted Air on the Environment. Carbon monoxide

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Chemistry and the Environment

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  1. Chemistry and the Environment ~Pollution

  2. Air pollution

  3. Air pollutants • Sulphur Dioxide • Nitrogen Dioxide (NO2) • Carbon Monoxide • Photochemical Oxidants • Respirable Suspended Particulates • Lead • Ozone

  4. Effects of Polluted Air on the Environment • Carbon monoxide i.) Failure of haemoglobin to carry oxygen in blood ii.) Cause death • Sulphur dioxides i.) Damage to respiratory system ii.) Increase in asthma attacks iii.) Formation of acid rain • Nitrogen oxides i.) Formation of photochemical smog ii.) Damage to lung tissue and blood vessel iii.)Formation of acid rain

  5. Hydrocarbons i.) formation of photochemical smog ii.) cause cancer • Ozone i.) Eye irritation ii.) Aggravates asthma iii.) Damage to plants iv) Deterioration of rubber and fabrics • Particulates i.) Constriction of respiratory passage ii.) Damage to lung tissue iii.) Cause cancer

  6. Ozone • Pale blue gas with pungent odour • Form by • Reaction between nitrogen oxides hydrocarbons in sunlight • Oxygen through an electrical discharge • Electric sparks occur in car engine and electrical applainces

  7. Depletion of Ozone Layer • Past few decades, ozone concentration fall over the Antarctica and Arctic • It Related to the release of chlorofluorocarbons (CFCs) • It increase the absorption of UV light by stratosphere • Cause skin cancer, eye cataracts and reduce crop yields.

  8. Water Pollution

  9. Causes of water pollution • Domestic wastes ----- detergents • Agricultural wastes ----- pesticides, excessive fertilizers • Industrial wastes ----- organic matter, detergents, poisonous chemicals, oil, suspended particles.

  10. Water pollution effects on the environment • Anaerobic decomposition of organic matter • Inorganic Nutrient Pollution---Detergent • Inorganic Nutrients pollution---Excess fertilizers • Pesticides and Industrial Chemical Wastes • Oil pollution

  11. Anaerobic decomposition of organic matter • large amount of organic matter will remove all dissolved oxygen • self-purification stop • In absence of oxygen, anaerobic bacteria produces many unpleasant smelling gases such as methane, ammonia and hydrogen sulphides • most aquatic organisms die due to suffocation

  12. Inorganic Nutrient Pollution---Detergent • Detergent contains non-biodegradable branch-chained molecules • causes foaming and reduces the penetration of light to the submerged plants • reduces the rate oxygen dissolving in water • high phosphate content of detergents result in eutrophication • At night, floating algae will compete with fish for dissolved oxygen • The depletion of the oxygen content may kill the fish • floating plants may interfere both navigation and irrigation

  13. Inorganic Nutrients pollution---Excess fertilizers • Excess fertilizers washed from agricultural land into rivers will increase the nitrate content of water • high concentration of nitrate of water cause human disease • eutrophication occurs

  14. Pesticides and Industrial Chemical Wastes • poisonous chemicals, DDT cause pollution to poison human or other non-target organisms • Industrial Chemical Wastes (e.g. heavy metals) can be concentrated along the food chains. • It causes impaired vision, weakened muscles, mental retardation, paralysis and even death.

  15. Oil pollution • Cover the seashores kills seaweeds, molluses and crustaceans. • Spilled oil also kills sea birds because of the following reasons: • 1)   The sea birds cannot fly when their feathers become soaked with oil. • 2)   When the sea birds clean their feathers, they ingest sufficient oil to poison themselves

  16. 3)   The oil interferes with the insulation provided by the feathers so that the sea birds easily die of cold or pneumonia. • The oil contaminates Beaches and thus spoils a valuable recreational resource.

  17. Solid waste

  18. Disposal of solid waste • Incineration • Land filling

  19. Incineration • reducing the volume of the waste by about 85% • having no risk of causing water pollution • The incinerating municipal waste is the potential danger of pollution the atmosphere with toxic chemicals such as sulphur dioxide (SO2), carbon monoxide (CO), HCl, NO2

  20. land filling • wastes are compressed and covered with earth on landfill sites • the generation of landfill gas (mostly methane) and leachate cause pollution • In order to reduce pollution, landfill gas and leachate are collected and treated

  21. Pollution Problems Associated with the Disposal of Plastics • plastics do not undergo decomposition in landfill sites. • Delaying the reuse of the landfill sites • Incineration of plastic waste produces air pollutants such as hydrogen chloride which cause acid rain that damages the environment. • Sea animals have been suffocated to death by plastic bags • plasticizers leads to further ecological and environmental side effect.

  22. Possible solutions to pollutions problems of plastics • Development of Degradable Plastics 1.) Biopolymers 2.) Photodegradable plastics 3.) Synthetic biodegradable plastics --Recycling of Plastics plastics in the waste are separated, cleaned, pulverized, and remoulded into new plastic items

  23. Pollution Control in Hong Kong

  24. Environmental Protection Department (Since 1986) • Formulating policy proposals on environmental protection • Monitoring environmental quality • Enforcing environmental legislation • Drawing up plans for treatment and disposal of waste • Advising on the environmental implications of town plans • Providing complains and enquiries services

  25. Air pollution Index • It represents the air pollution that we shall be exposed to for most of the time • It related to concentrations of respirable suspended particulate (RSP), sulphur dioxide (SO2), carbon monoxide (CO), ozone (O3) and nitrogen dioxide (NO2) • level at or below 100 means that any pollutant levels are in the satisfactory range • level in excess of 100 means that levels of one or more pollutant(s) is/are in the unhealthy range. • The EPD has provided advice to public regarding precautionary actions

  26. API Air Pollution  Level Health Implications 0 to 25 Low Not expected 26 to 50 Medium Not expected for the general population 51 to 100  High Acute health effects are not expected but chronic effects may be observed if you are exposed to such levels persistently for a long time. 101 to 200 Very High People with existing heart or respiratory illnesses may notice mild aggravation of their health conditions. Generally healthy individuals may also notice some discomfort. 201 to 500 Severe People with existing heart or respiratory illnesses may experience significant aggravation of their symptoms. There may also be widespread symptoms in the healthy population (e.g. eye irritation, wheezing, coughing, phlegm and sore throats).

  27. Measures to Improve Air Quality • Using unleaded petrol (ULP) • Install catalytic converters in car exhaust systems • Limitation of sulphur content in fuel • Desulphurization of flue gas • Install electrostatic precipitators in power plants

  28. Use of Unleaded Petrol (UPL) • Leaded compound(tetraethyllead) in petrol used in order to prevent knocking. • Lead compounds react with other chemicals to form lead halide. • Lead halide are toxic. Cause anaemia, hyperactive of children. • Unleaded petrol reduce the toxic lead compounds in atmosphere. • UPL was introduce in April 1991. • Over 77% petrol are UPL by the end of 1995.

  29. Installation of Catalytic Converters • Help reduce the emission of Nitrogen oxides, Carbon monoxides, Unburnt hydrocarbons. • Rhodium and Plantium as catalyst. • Carbon monoxide is oxidized to carbon dioxide and water. 2CO(g) + O2(g) 2CO2(g) • Unburnt hydrocarbons is oxidized to carbon dioxide and water • Nitrogen oxides are reduced to Nitrogen. 2NO(g) + 2CO(g)  N2(g) + 2CO2(g) • Leaded petrol inactive the catalyst in the converters.

  30. Limitation of Sulphur Content in Fuels • Start from 1990, the sulphur content in liquid fuel is limited to 0.5% by weight. • In solid fuel is limited to 1% by weight. • Since April 1995, fuel used in vehicles must not contain more 0.2% sulphur content by weight.

  31. Desulphurization of Flue Gas • Sulphur dioxide is releases during combustion of coal in power generation. • Flue gas desulphurization(FGD) was used in generating unit. • FGD utilized ‘wet limestone- gypsum scrubbing process’ which can remove 90%of sulphur dioxide during burning of coal. • The treated flue gas is dispose to atmosphere through the tall chimney. • The gypsum can use as raw material in making cement.

  32. Electrostatic Precipitators in Power Plants • Over 99% of the fly ash from flue gas is removed. • Flue gas pass through a chamber where particulates become charged. • The charged particles attach to a collecting electrode and then neutralized. • Lastly, flue gas discharged through the chimney.

  33. Measures to Improve Water Quality • Treatment in sewage • Treatment of chemical waste from industry and laboratories • Legislation and Education

  34. Treatment of sewage • Sewage first pass through a screen to remove large objects • Then sewage was sent to sedimentation tanks for suspended solids settle out • Then pass into aeration tanks where microorganism digest the organic matter into simpler form • Lastly, the treated sewage is chlorinated to kill the microorganism before discharge to the sea or river.

  35. Treatment of Chemical Waste • InApril 1993, the Chemical Waste Treatment Center (CWTC) provide proper waste treatment service for local waste producers. • CWTC recovers waste oil from oily water mixture. • Treats water base-chemical waste and water containing heavy metals • Destroy hazardous organic waste such as cyanide.

  36. Legislation and Education • Heavy fine for untreated agricultural and industrial wastes into river or seas. • The permitted level of toxic substance in industrial effluents should be stricter. • Legislation should hold companies financially responsible for all oil pollution damage resulting from their activities • The public should be educated through mass medium and campaigns that arouse the public the sense of responsibilities

  37. Measures to Reduce solid waste • Reuse waste • Recycle waste • Renewable waste

  38. THE END By Chau Wai Kin (1) Wong Chi Wah (14)

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