Biosorption of Heavy Metal Ions: Ion-exchange versus Adsorption and theHeterogeneity of Binding Sites

摘要

Surface heterogeneity-related effects have been studied in thecontext of biosorption systems designed for the removal of bivalent heavy metalions from aqueous systems. The research was focused on incorporating theseeffects into the concept of the ion-exchange (1E) constant. Cases of both correlatedand uncorrelated values of the affinity constants towards metal ions and protonswere considered. When strong correlations were assumed, the dispersion of the 1Econstant was smaller (or, in the limiting case, the same) in comparison to thedispersions of the affinity constants. In contrast, when no correlation was assumed,the dispersion of the IE constant was greater than those corresponding to any of theaffinity constants. The dispersion of the IE constant could be additionally enhancedby the existence of multi-dentate binding modes related to the metal ions.