Experimental study of chromium adsorption on minerals in the presence of phthalic and humic acids

摘要

The effect of phthalic acid (benzene 1,2 dicarboxylic acid),a surrogate compound for natural organic matter,and of humic acid,on the adsorption of chromium to the surface of minerals was observed.In ternary systems involving phthalic acid,chromium(III) adsorption decreases on clays,probably because of aqueous Cr(III)-phthalate complexation,preventing ionic-exchange.Phthalic acid was also found to reduce chromium(VI) adsorption onto alumina,because of a competitive effect.In ternary systems involving humic acid,Cr(III) adsorption is increased in the low pH range because of the formation of surface ternary complex S-L-Cr(III) and is decreased in the high pH range because of aqueous Cr(III)-humate complexation.