At School… Hey guys, don’t you ever wonder why the air’s so bad now? Must be all the CO Mr Chiu keeps going on about No! It’s the NO x ! You girls are so dumb It’s the SO x It’s the VOCs Or the Particulates…
Composition of Air Air is composed of around 78% Nitrogen, 21% Oxygen, 1% Argon and 0.03% CO 2. An excess of any of these gases or the presence of unwanted gases, which may harm the environment or our health, are AIR POLLUTANTS!
The Main Pollutants Are… Carbon Monoxide Particulates Sulfur Oxides (SO x ) Nitrogen Oxides (NO x ) Volatile Organic Compounds (VOCs) Sammy
Carbon Monoxide One of the sources of CO is the incomplete combustion of methane, or CH 4. CH 4 (g) + 1.5O 2(g) CO (g) + 2H 2 O (g) Another source is from the combustion of fossil fuels, such as coal. C 8 H 18(g) + 8.5O 2(g) 8CO (g) + 9H 2 O (g) 2CH 4(g) + 3O 2(g) 2CO (g) + 4H 2 O (g)
Nitrogen Oxides Nitrogen naturally comes from thunder storms and biological processes. Combustion engines in jets or cars also produce NO N 2(g) + O 2(g) 2NO (g) 2NO (g) + O 2(g) 2NO 2(g)
Sulfur Oxides The combustion of coal is a man-made source of SO 2 and SO 3. S (g) + O 2(g) SO 2(g) 2S (g) + O 2(g) 2SO 3(g) Volcanoes also emit SO 2. 2H 2 S (g) + 3O 2(g) 2SO 2(g) + 2H 2 O (g)
Volatile Organic Compounds Partially burned fuels such as gasoline produce VOCs. The usage of solvents, paints, wax and some cosmetic products wax will also produce VOCs. Plants naturally emit these pollutants in the form of terpenes (hydrocarbons with the formula C 10 H 16 )
Particulates Particulates are naturally found in the atmosphere in the form of dust, soot, sand, smoke, pollen, and ash. The combustion of fossil fuel also emits particulates.
Test Yourself! Which 2 pollutants will burning fossil fuels produce? What pollutant is the car producing? What compound will the electrical storm generate? What gas will the volcano emit? What gas arises from the decay of organic matter?
Phew finally some fresh air! How do we keep it this way though?
Methods of Reduction… Reduce CO, NO x and VOCs by using a catalytic converter, which converts these compounds into CO 2 and water. Use lean burn engines to reduce CO and NO x , which increase efficiency of engines by reducing throttling losses. Removing sulfur from fossil fuels such as coal and using in power plants will decrease SO 2 emissions. The level of particulates can be greatly reduced by using sedimentation chambers, which purifies the air, and electrostatic precipitation, which also removes particulates from flowing gases.