Adsorption properties are the primary properties of activated carbon. Activated carbon has like graphite crystal grains but irregularly arranged microcrystals. activated carbon pellets manufacturer During the activation process, pores of different shapes and sizes are generated between the crystallites. Assuming that the pores of activated carbon are cylindrical pores, the radius of the pores can be divided into two types according to a certain method.
1. According to IUPAC: micropores <1.0nm; mesopores (also called transition pores) 1-25nm; macropores>25nm.
2. According to habits: micropores <150nm; mesopores 150-20000nm; macropores> 20000nm.
The pore volume of micropores is generally about 0.25-0.9ml/g, the number of pores is about 1020/g, and the surface area of all micropores is about 500-1500m2/g, usually measured by the BET method, and it is also called as high as 3500-5000m2/g of. Almost 95% of the surface area of activated carbon is in the micropores. Therefore, except for some macromolecules that cannot enter, the micropores are an important factor that determines the adsorption performance of activated carbon.
The pore volume of mesopores is generally about 0.02-1.0ml/g, and the surface area is as high as several hundred m2/g, generally only about 5% of the total surface area of activated carbon. wan yang activated carbon Its function can adsorb steam, and can provide channels for adsorbents to enter the micropores, and can directly adsorb larger molecules.
The pore volume of macropores is generally about 0.2-0.5ml/g, and the surface area is only 0.5-2m2/g. Its function is to make the adsorbate molecules penetrate into the smaller pores of the activated carbon quickly; second, when used as a catalytic carrier, the catalyst often A small amount of precipitation is in the micropores, mostly in the macropores and mesopores.
The surface area of activated carbon mentioned includes internal surface area and external surface area. In fact, the adsorption properties mainly come from the huge internal surface area. Therefore, it should not be mistaken that grinding activated carbon will increase the surface area and thereby increase the adsorption capacity.