Chemistry

Preservation of atmospheric air


Big cities of the world, with their cars and factories, release huge amounts of toxic gases and solid particles into the atmosphere.

This pollution is a threat to human health and life in general. The smoke that pollutes the air comes from burning fuels like:

- coal, steel, metallurgical and etc;
- gasoline from cars;
- diesel, factories and automobiles;
- wood from forest burnings.

These fuels when burned generate tons of pollutants, which go into the atmospheric air.

Toxic gases

There is already a definite approximate amount of gases in the atmosphere. If there is excess of other toxic gases, we say that the air is polluted.

Carbon monoxide (CO) is an odorless (odorless) and colorless (colorless) gas that can cause death. It is obtained by burning some carbon-containing fuels (C).

When inspired, it reaches the lungs and goes to the blood. It penetrates into the red blood cells or red blood cells and combines with the substance hemoglobin, which is responsible for the transport and distribution of oxygen. Causes weakening of blood vessels, nausea and diarrhea. A person subjected to high CO concentrations may die of asphyxiation.

Carbon dioxide (CO2) accounts for 0.04% of the total composition of gases in the atmosphere. It is very important for life on earth. Assists in photosynthesis of plants. The concentration of this gas has been increasing in the atmosphere due to the burning of fossil fuels and derivatives. This increase in the concentration of this gas may cause the greenhouse effect.

Solar radiation (light and heat in the form of IR infrared radiation) travels through the atmosphere, reaches the earth's surface and is reflected. Part of this heat stays on the surface and some goes into space. From the heat that goes into space, part goes through the atmosphere and the other gets trapped in the atmosphere. This is the greenhouse effect that warms the earth. If there is too much carbon dioxide, the less IR radiation goes into space. This heat gets trapped in the earth, raising the temperature. That's what we call Global warming.

Sulfur dioxide (SO2) and nitrogen oxides (eg NO2) also appear in the atmosphere as a result of the burning of fossil fuels and their derivatives.

They may cause burning eyes, irritation of the nose, throat and bronchi. In the atmosphere, these gases combine with rainwater causing various chemical reactions. Then they return to the earth's surface in the form of acid rain, causing serious damage to man and the environment.

Rain is usually already acidic, but with pollution it becomes even more acidic.

Normal Rain (Slightly Acid):

H2O + CO2 → H2CO3 carbonic acid formation

Acid rain:

H2O + SO2 → H2ONLY3 sulfurous acid formation

H2O + SO3 → H2ONLY4 sulfuric acid formation

H2O + NO2 → HNO3 nitric acid formation

Acid rain can destroy crops, causes river poisoning by killing fish and other marine animals. Erodes cars, monuments, marbles and houses.

Chlorofluorocarbon (CFC) or gas freon It was created in 1928 for use in refrigerators, air conditioners, aerosols (spray) and to make porous plastics.

CFC, as well as methane (CH4) can destroy the ozone layer. Decreasing or thickening this layer can change the climate on earth. It also increases UV (ultraviolet) radiation causing more cases of skin cancer in humans.

Styrofoam is a CFC-containing material that is neither degradable nor recyclable. It occupies a lot of space because it is not too dense. It is also considered an environmental polluting agent.

Heavy metals

Heavy metals such as lead (Pb), mercury (Hg) and cadmium (Cd) are thrown into the air through chimneys, foundries and mines.

Hg poisoning can cause harm to the body such as inflammation in the mouth, tooth loss, nausea, blindness and can lead to death.

In Brazil, Hg is widely used in mining areas. It serves to form a mixture with gold (Au), separating it from impurities. Soon after, the prospector uses the torch to evaporate the Hg and obtain the gold. The evaporated Hg is inhaled by this prospector, intoxicating him. Metal can pass from the atmosphere to river water, contaminating fish and other animals consumed as food by man.

To reduce air pollution, filters are used in industrial chimneys. The air is lighter and cleaner, therefore more suitable for the breathing of living beings.