Activated carbon detailed introduction

Activated carbon is a general term for carbon materials that are made from carbon-containing raw materials such as wood, coal and petroleum coke through pyrolysis and activation. It has a developed pore structure, a large specific surface area and abundant surface chemical groups, and has strong specific adsorption capacity.
It is usually a porous amorphous carbon with strong adsorption capacity in powder or granular form. It is obtained by carbonizing solid carbonaceous materials (such as coal, wood, hard nut shells, fruit cores, resins, etc.) at a high temperature of 600-900°C under air-tight conditions, and then oxidizing and activating them with air, carbon dioxide, water vapor or a mixture of the three at 400-900°C.
Carbonization volatilizes substances other than carbon, and oxidative activation can further remove residual volatile substances, produce new and expand original pores, improve microporous structure, and increase activity. Carbon activated at low temperature (400°C) is called L-carbon, and carbon activated at high temperature (900°C) is called H-carbon. H-carbon must be cooled in an inert atmosphere, otherwise it will turn into L-carbon. The adsorption performance of activated carbon is related to the chemical properties and concentration of the gas during oxidation activation, the activation temperature, the degree of activation, the inorganic composition and content in the activated carbon, and other factors, and mainly depends on the properties of the activated gas and the activation temperature.
The carbon content, specific surface area, ash content and pH value of the activated carbon's aqueous suspension all increase with the increase of the activation temperature. The higher the activation temperature, the more complete the volatilization of the 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. Ash is mainly composed of K2O, Na2O, CaO, MgO, Fe2O3, Al2O3, P2O5, SO3, Cl-, etc. The ash content is related to the raw materials for the preparation of activated carbon, and the ash content in the carbon increases with the removal of volatiles in the carbon.
As of 2007, the world's annual activated carbon production reached 900kt, of which coal-based activated carbon accounted for more than 2/3 of the total production; China's annual production has exceeded 400kt, ranking first in the world. The United States, Japan and other countries are also major activated carbon producing countries in the world.