Activated carbons are generally classified into two groups:
Activated Carbons for Liquid phase Adsorption - These activated carbons feature higher percentage of macropores or medium pores that allow large molecules adsorption. They are used for removing organic compounds causing unwanted color, taste or odor in different liquids.
There are two types of liquid phase carbons differing only in the particle size. The finer the particle size of an activated carbon, the better the access to the surface area and the faster the rate of adsorption kinetics, but pressure drop in the fluid must be considered.
Granular Activated Carbon (GAC)– Features irregular shaped particles that are put inside a container with the liquid to be treated. GAC is manufactured in different particle size depending on the specific application.
Powder Activated Carbon (PAC) – Particle size is the only difference with granular presentation. When using powder carbon, it is added to the liquid in a stirring container to maintain a homogeneous suspension. After a proper time of contact (10 to 20 min), it is left for sedimentation or separated using a filter.
Activated Carbons for Vapor phase Adsorption – They feature a higher average of micropores used for small molecules adsorption. They are used for air treatment, industrial process gas purification, solvent recovery and as a catalyst.