Effects of nonreversibility, particle concentration, and ionic strength on heavy-metal sorption

Adsorption/desorption isotherm data for nickel and cobalt, and reversible component sorption as a function of pH value, ionic strength, and particle concentration, were examined. The reversible component partition coefficient for these metals sorbed to montmorillonite and quartz was a function of particle concentration. Simple resuspension and dilution experiments suggested that the observed effect was not due to experimental artefacts or hidden variable functions. A mathematical model was developed which suggested the existence of a desorption reaction that resulted from particle-particle interactions (which were shown to be independent of ionic strength). The observed decrease in partition coefficient with increasing ionic strength was attributed to a decrease in the classical, low particle concentration limit, partition coefficient. A bibliography of 41 references is appended.