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Clean the air filter with activated carbon 

Since the 1600s - BC, the Egyptians were known use of charcoal adsorbent for medical purposes ability of activated carbon to adsorb large amounts of gases.

From the early 20th century has been activated carbon production of goods and began to be used to filter the air. The poison gas attack in the first war of the engine was really motivates people to use charcoal to purify the air. Activated carbon filters in gas weapons have prevented the harm of toxic gases. At first, these filters containing granular coal (from coconut) porous. The filter has proved very effective, although at the time of human knowledge about the adsorption process and the factors that influence the effectiveness of activated carbon filtration is limited.

Since World War I onwards, activated carbon is widely used in many air filters, filters from several dozen small liters / minute to large, filter a few hundred m3 / hour. The smaller filter is used in protective masks room toxic gases and vapors, while the ultra-large to be used to filter the air for factories, offices, military bases or reducing the waste gases and vapors generated during industrial production. Activated carbon can be produced from wood, peat, coal, peanut shells, lignite and polymers etc .. Most organic materials converted to activated carbon by the heat of steam or CO2 at temperatures height. Inside the pore structure was developed by the oxidative phase control, so can create the type of carbon has its own characteristics.

In addition, activated carbon can be produced using inorganic chemicals, such as zinc chloride or phosphoric acid to promote pyrolysis of carbohydrates, thus carbonization process can occur at low temperatures more. Inorganic salts are washed out of the product and will create the type of activated carbon micro-porous structure suitable for adsorption of large molecules.

Activated carbon is mainly the microcrystalline graphite chaotic arrangement naturally with a surface area of over 700m2 can / g.

Generally, the surface of activated carbon is not polarized, making this material and preferred hydrophilic organic matter although on the surface oxidation can do it with the polarity bit. The combination of large surface area with no polarization properties of activated charcoal has strong adsorption. For air filters, activated carbon is used as a seed, not a powder to reduce to a minimum the pressure drop in the filter. Since adsorption kinetics depend on particle size should need to adjust the balance between adsorption ratio maximum and minimum pressure drops, coal or grain size used is 1 - 2 mm.

When using charcoal, it is important first to distinguish the nature of gases and vapors. Actually a bit of organic compounds with boiling point below 65oC only activated carbon filter adsorption weak, whereas the Clean Air prone desorption.

The mechanism of activated carbon filter for vapor of organic compounds with low boiling point is the same as for the gas.

Usually steam coal activated carbon adsorption mechanism of physical adsorption. However, chemical adsorption and capillary condensation phenomenon also contributed in it. Activated carbon adsorption (physical mechanism) of gas pretty bad that people have to support chemical method by impregnating chemicals into charcoal to keep or decomposition gases.

The metal salts of copper, silver, chromium, zinc and organic compounds (eg amines) was used for the adsorption of toxic gas used in war.

However, the use of chemical impregnated activated carbon to reduce the possibility of physical adsorption of toxic fumes. Requirements for air filtration systems used on military purpose is to ensure that filters are many gases and vapors; means that the various chemicals used for impregnation on activated carbon dose must be given and not interfere with each other. If the gas is toxic decomposition products, the filter must also have the ability to absorb them all.

Although the surface of activated carbon but hardly polarized absorption capacity of the air filter is easy to be affected by water vapor is adsorbed water vapor. Steam reduces the adsorption capacity of the filter toxins. Therefore, only use it when you open the lid of the new filter.

Air filters used in military field (such as respirators) is not the same as those applied in the civilian sector. It includes both the structure of activated carbon filter particles and gases / vapors toxic porous cellulose paper.

The design must calculate how to go into the airflow is distributed evenly and contact with the adsorbent in the best way. Most filters are used activated carbon for air flow along the axis, and a number of different types have designed radial airflow. Time saved in the buffer gas flow filters used for military purposes at about 0.4 to 0.6 seconds, up to toxic gases are adsorbed to carry weapons to protect the gas. Placing padding