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EFFECT OF IMPURITIES ASSOCIATED WITH ALUMINOSILICATES ON ARSENIC SORPTION AND OXIDATION
Lin**, Z. AND R W. Puls*. EFFECT OF IMPURITIES ASSOCIATED WITH ALUMINOSILICATES ON ARSENIC SORPTION AND OXIDATION. HYDROLOGICAL SCIENCE AND TECHNOLOGY 15(Specl):130-137, (1999).
Arsenite, As(III), and arsenate, As(V), are of increasing environmental concern. Risk assessment and risk management of arsenic contaminated sites requires a better understanding of arsenic-mineral interactions. Aluminosilicate minerals, such as feldspars and clays, are the most abundant constituents occurring in aquifer sediments, soils, and as suspended particles in ground water. Naturally occurring substances (e.g, iron, manganese, humic acid) can associate with minerals. consequently, they could influence the behavior of alominosilicate minerals to arsenic adsorption. This laboratory work demonstrated that Fe and Mn oxide coatings on feldspar and kaolinite could alter the surface physicochemical properties of the minrals, causing an increase in the adsorption of arsenite and arsenate. Minerals treated with humic acid showed a significant decrease in the adsorption of As(V), but little change in the adsorption of As(III). The oxidation of As(III) to As(V) was significantly catalyzed by iodine ions associated with minerals, although present in trace amounts..