E1-Air Pollution! Heather Yin Period 3

Why Should I Care?! As humans populate the planet, we produce waste that is absorbed by our atmosphere which directly affects our environment. Thanks to the harmful effects of waste and our inability to dispose of this waste properly and efficiently, our environment easily becomes polluted. Chemical compound in the air influence human life and health. Air pollution is just one type of environmental pollution.

Fun Facts. Non-polluted air consists of 78% nitrogen gas, 21% oxygen gas, 1% argon, and 0.03% carbon dioxide! While polluted air is overwhelmed with primary or secondary pollutants, such as; carbon monoxide, nitrogen oxides, and sulfur oxides!

Primary vs. Secondary Pollutants Primary pollutants – Added directly to the air from any source. Ex: A burning fire creates the primary pollutant known as carbon monoxide. – Five major primary pollutants: Carbon monoxide(CO), oxides of nitrogen(NO x ), oxides of sulfur(SO x), particles and volatile organic compounds(VOCs). Secondary pollutants – Formed, not added, in the atmosphere from chemical reactions. Ex: Formation of the ozone layer.

Carbon Monoxide! -Polar molecule consisting of covalent bonding between atoms. -Colorless, odorless, tasteless, toxic! -Not soluble in water. -Results from burning wood/fossil fuels. -Most CO production is very easily emitted into the air because most of it is formed naturally. Most comes from the oxidation of methane gas, CH 4. (2CH 4(g) + 3O 2(g)  2CO (g) + 4H 2 O (l) ) -Methane is a noxious gas and is produced from the decomposition of organic matter like lakes and oceans. -Some CO emissions come from man- made sources like car emissions, industry emissions, and even forest fires! -When poor mixing of fuel and air takes place or a hydrocarbon can’t react completely with amount of oxygen present, carbon monoxide is produced. This is known as incomplete combustion (hydrocarbon + oxygen  carbon dioxide + carbon + carbon monoxide + water )

Oxides of Nitrogen (No x ) -8 oxides of nitrogen where nitrous oxide is found naturally, also known as N 2 O or dinitrogen monoxide. -Any reactions between nitrogen and oxygen gas is VERY endothermic. However, around 1500 degrees celsius, NO x can be produced. -Man-made waste only produces about 10% of NO x which usually comes from cars, planes, furnaces, and agricultural burning. -N 2(g) + O 2(g)  2NO (g) -N 2(g) + 2O 2(g)  2NO 2(g) -As NO is produced as a primary pollutant, it converts to NO 2, a secondary pollutant. - Fun Fact: High energy in lightning can result in formation of N 2 O and NO.

Oxides of Sulfur (SO x ) -S + O 2  SO 2 -Produced the most out of all the primary pollutants. -Produced by volcanoes and combustion of sulfur containing fuels like coal and petroleum, however, most sulfur oxides are created from man-made objects. -Reacts in atmosphere as acid rain! -Nitrogen oxides react with water to form nitrous acid and nitric acid. 2NO 2 (g) + H 2 O(l)  HNO 2 (aq) + HNO 3 (aq) -Forms from metal pollutants and finely divided particulates like ash and sunlight can speed up the reaction. -Various oxides are: N 2 O (+1), NO ( +2), and NO 2 (+4). Nitrogen dioxide differs in that it is made as a secondary pollutant from NO. -2H2S(g) + 3O2(g)  2 SO2(g) + 2H2O(l)

Acid Rain is one of the unfortunate results of sulfur dioxide and nitrogen oxides production. Coal combustion is the biggest contributing factor to sulfur oxide pollutants. Sulfur dioxide is primarily rooted from man-made sources.

Particulates/Volatile Organic Compounds -Particulates: Solid particles suspended or carried in air, large enough to be seen. Sandstorms, volcanoes, forest fires. Asbestos is a good example. -Dust, smoke and soot, metallic particles, coal, ash. -Volatile Organic Compounds: primary pollutants introduced directly into environment. -Methane: simplest alkane, largest natural source of hydrocarbons, produced by bacterial decomposition in swamps/oceans. -Smog: secondary pollution from automobile exhausts, contains methyl benzene: C 6 H 5 CH 3 - Petroleum extracting, refining. - Health wise- Can cause irritation of lungs, mucous membrane, can cause emphysema.

Catalytic Converters Oxidize carbon monoxide  carbon dioxide. Oxidize nitrogen monoxide  nitrogen gas. 2CO (g) + 2NO (g)  2CO 2(g) + N 2(g) Oxidize volatile organic compounds  carbon dioxide/water Reduces CO, NO x, VOCs

Reducing Automobile Pollution Lower air to fuel ratio: Lack of air reduces amount of nitrogen oxides produced. Air injected into exhaust gases. Lean burn engines: Higher air to fuel ration. Less carbon monoxide and VOCs, but nitrogen oxide levels will increase. Use of non-leaded gas to eliminate lead pollution. Catalytic Converters are most effective.

Reducing Automobile Pollution Lower Air to Fuel Ratio:Lean Burn Engines:

Reducing Oxides of Sulfur and Particulates Convert high sulfur percentage coal into natural gas like SNG. Remove most sulfur, convert to hydrogen sulfide gas. S (s) + H 2(g)  H 2 S (g) Use low amounts of sulfur. Remove sulfur with hydrogen gas. Coal washing, retract sulfur. Coal is finely ground, washed with water. Sulfur can still be present which proves as a disadvantage. Particulates can be reduced most effectively through the principle of electrostatic precipitation. Electrons produced will collect on particulates and will be moved to collector plates—eliminates more than 98% of particulates. Wet alkaline scrubber: cleaning device that uses a liquid with counter flow method to remove contaminants.

Air Pollution Is Not an Ephemeral Problem. XMQ