What Is Activated Carbon Properties

2021-09-26

Activated carbon is composed of graphite microcrystalline, single plane network carbon and amorphous carbon, in which graphite microcrystalline is the main part of activated carbon.

The microcrystalline structure of activated carbon is different from that of graphite. The layer spacing of microcrystalline structure is between 0.34 ~ 0.35nm and the gap is large. Even if the temperature is above 2000 ℃, it is difficult to convert into graphite. This microcrystalline structure is called non graphite microcrystalline, and most activated carbon belongs to non graphite structure. The microcrystals of graphite structure are arranged regularly and can be transformed into graphite after treatment.

Non graphitic microcrystalline structure makes activated carbon have developed pore structure, which can be characterized by pore size distribution. The pore size distribution of activated carbon ranges from less than 1 nm to thousands of nm. Some scholars have proposed that the pore diameter of activated carbon can be divided into three categories: micropores with pore diameter less than 2nm, mesopores with pore diameter of 2 ~ 50nm, and macropores with pore diameter greater than 50nm.

The specific surface area of micropores in activated carbon accounts for more than 95% of the specific surface area of activated carbon, which determines the adsorption capacity of activated carbon to a great extent. The mesoporous specific surface area accounts for about 5% of the specific surface area of activated carbon. It is the adsorption site of larger molecules that can not enter the micropores, and capillary condensation occurs under high relative pressure. The specific surface area of macropores generally does not exceed 0.5m2/g. It is only the channel for adsorbate molecules to reach micropores and mesopores, which has little effect on the adsorption process.