Adsorption of organic compounds from aqueous solutions on silica gel and α-aluminum oxide:: A charge control model

A model for electrostatic interactions in the adsorption of aromatic and heterocyclic compounds on silicon and aluminum oxides was considered. It was concluded that the adsorption properties of organic molecules are determined by the ratios between the effective charges of their atoms (Q(R)) and atoms in water molecules (Q(O) and Q(H)). It was shown experimentally that only the compounds for which Q(R) is higher than Q(O) and Q(H) are adsorbed on silica gel and alpha-aluminum oxide from aqueous solutions. It was found that adsorption constants of aromatic amines correlate with effective charges of nitrogen atoms.