The process of capturing molecules through the adhesion of atoms, ions, biomolecules or molecules of gas, liquid, or dissolved solids to a surface (not to be confused with absorption).  This is the mechanism by which activated carbon filtration works.  Once the surfaces of a grain of activated carbon are completed coated with adsorbed particles, the filter is exhausted and performance drops.  Therefore, the higher the filter surface area, the more effective the filter performance in removing contaminants and the longer the filter lasts.