Zinc (Zn) and arsenate (As) often coexist in soils. However, little is known concerning the effects of coexisting As on Zn adsorption and precipitation on soil minerals. In this study, adsorption and precipitation of Zn on γ-alumina in the absence and presence of arsenate was investigated employing batch experiments and extended X-ray absorption fine structure (EXAFS) spectroscopy. Results indicated that Zn formed edge-sharing tetrahedral surface complexes at pH 5.5 and Zn-Al LDH-like (layered double hydroxide) precipitates at pH 7.0 on the surface of γ-alumina. The presence of arsenate significantly enhanced Zn sorption densities, and remarkably changed its bonding environment. At pH 7.0, when Zn was preequilibrated with γ-alumina prior to the As introduction, mixed Zn-Al LDH-like and adamite-like precipitates formed. However, when Zn and As were added simultaneously, only adamite-like precipitate was observed. Zn-arsenate precipitates could significantly decrease the concentration of Zn in aqueous solution and the bioavailability and mobilization of Zn in soils.

Macroscopic and microscopic investigation of adsorption and precipitation of Zn on γ-alumina as affected by As

249th National Meeting (2015)

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