Binding Characteristics of Pb2+ on Anion-Modified and Pristine Hydrous Oxide Surfaces Studied by Electrophoretic Mobility and X-Ray Absorption Spectroscopy.
We examine the role of coadsorbed phosphate and sulfate on the adsorption of Pb2+ at the oxide-water interface of goethite and boehmite by electrophoretic mobility (EM) and X-ray absorption spectroscopy (XAS). Comparisons to Pb2+ adsorbed to pristine oxides are provided. Pb2+ binds as an inner-sphere complex to pristine goethite and groups into oxy-clusters on pristine boehmite under our conditions. The presence of either anion at the surface generally increases the ability of the solids to sorb Pb2+ but by different mechanisms. Adsorbed phosphate on both solids acts as a reactant to form lead phosphate surface phases that may be highly dispersed. The more mobile sulfate ion is more effectively adsorbed when Pb2+ is present, and increases Pb2+ adsorption on boehmite. Lead sulfate phases may form at the goethite surface under our conditions. Copyright 1998 Academic Press.
Weesner
FJ
Department of Soil Science, University of Wisconsin-Madison, 1525 Observatory Drive, Madison, Wisconsin, 53706
Bleam
WF