THE EFFECT OF TEMPERATURE AND PH ON THE ADSORPTION OF COPPER(II), LEAD(II), AND ZINC(II) ONTO GOETHITE

Adsorption of copper(II), lead(II), and zinc(II) from aqueous solution (initially 10−4 or 10−5M) onto synthetic goethite (α-FeOOH) has been measured as a function of pH at several temperatures between 10 and 70°C. In all systems the adsorption edges shifted to lower pH as the temperature increased. The order of temperature dependence was found to be Zn > Cu ≈ Pb; this is shown to be consistent with the hypothesis that adsorption is closely related to cation hydrolysis. The James−Healy model for adsorption of hydrolyzed species, with the use of a single adjustable parameter, ΔGchem, for each cation, correctly predicted both the direction and magnitude of the temperature dependence of the pH range for adsorption, but failed to account for its concentration dependence. © 1993 by Academic Press, Inc.