PHYSICOCHEMICAL FUNDAMENTALS OF SOIL DECO NTAMINATION - ADSORPTION OFORGANIC CONTAMINANTS ONTO CA-BENTONITE

As a model of chemical soil contamination, adsorption of aniline and p -nitrophenol onto Ca-bentonite at different pH has been studied. At pH around the value corresponding to pK(s) aniline is adsorbed to the ma ximal extent of almost-equal-to 15%. So we may conclude that this cont aminant is mainly adsorbed by ion exchange as aniline cation. Desorpti on or soil decontamination may be achieved by HCl or NaOH to almost-eq ual-to 30% under clay destruction; however, through ion re-exchange wi th an excess amount of CaCl2, 100% of aniline is desorbed. Alternative ly, aniline may be removed from bentonite by oxidation in air at 250 t o 400-degrees-C. Nitrophenol is only very weakly adsorbed at any measu red pH.