What is activated carbon?

Activated carbon is prepared by pyrolysis and activation processing of carbon-containing raw materials such as wood, coal and petroleum coke. It has developed pore structure, large specific surface area and abundant surface chemical groups, and has strong specific adsorption capacity. A collective term for carbon materials.

Usually powder or granular porous amorphous carbon with strong adsorption capacity. Carbonized by solid carbonaceous materials (such as coal, wood, hard nut shells, fruit cores, resins, etc.) at a high temperature of 600 to 900 ℃ under air isolation, and then use air, carbon dioxide, water vapor or water vapor at 400 to 900 ℃ The mixed gas of the three is obtained after oxidation activation.

Carbonization volatilizes substances other than carbon. Oxidation activation can further remove residual volatile substances, create new and expand original pores, improve microporous structure, and increase activity. Low temperature (400℃) activated carbon is called L-carbon, and high temperature (900℃) activated carbon is called H-carbon. H-carbon must be cooled in an inert atmosphere, otherwise it will be transformed into L-carbon. The adsorption performance of activated carbon is related to the chemical properties of the gas during oxidation activation and its concentration, activation temperature, activation degree, the composition and content of inorganic substances in activated carbon and other factors, and it mainly depends on the nature of the activated gas and the activation temperature.

The carbon content, specific surface area, ash content and pH value of the water suspension of activated carbon all increase with the increase of activation temperature. The higher the activation temperature, the more complete the volatilization of residual volatile substances, the more developed the microporous structure, the greater the specific surface area and adsorption activity

The ash composition and content in activated carbon have a great influence on the adsorption activity of carbon. The ash content is mainly composed of K2O, Na2O, CaO, MgO, Fe2O3, Al2O3, P2O5, SO3, Cl-, etc. The ash content is related to the raw materials used to make activated carbon, and with the removal of volatiles in the carbon, the ash content in the carbon increases. Big.

As of 2007, the world's annual output of activated carbon reached 900kt, of which coal-based (quality) activated carbon accounted for more than 2/3 of the total output; and China's annual output has exceeded 400kt, ranking first in the world. The United States, Japan, etc. are also the world's major producers of activated carbon .