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Factors Influencing Arsenite Removal by Zero-Valent Iron |
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| Authors: | Xueyuan Yu Christopher Amrhein Yiqiang Zhang Mark R. Matsumoto |
| Affiliation: | 1San Diego Regional Water Quality Control Board, 9174 Sky Park Court, Ste. 100, San Diego, CA 92123-4340. E-mail: heyu@waterboards.ca.gov 2Professor, Dept. of Environmental Sciences, Univ. of California, Riverside, Riverside, CA 92521. E-mail: christopher.amrhein@ucr.edu 3Postgraduate Researcher, Dept. of Environmental Sciences, Univ. of California, Riverside, Riverside, CA 92521. E-mail: yiqiang.zhang@ucr.edu 4Associate Dean for Research and Graduate Education, Bourns College of Engineering, Univ. of California, Riverside, Riverside, CA 92521 (corresponding author). E-mail: mark.matsumoto@ucr.edu |
| Abstract: | The effects of pH, alkalinity, and mass transfer efficiency on the removal of arsenite [As(III)] by zero-valent iron (ZVI) were evaluated in this study. The optimum pH range for removal of As(III) was found to be between 7 and 8. As(III) removal varied with salinity, pH, alkalinity conditions, and As(III) concentration. Degradation of As(III) removal performance was observed only under conditions of high alkalinity and arsenic concentrations [alkalinity >10?g CaCO3/L and 2.9?mg/L As(III)]. A strong correlation between As(III) removal and increasing Reynolds number in batch testing suggests that mass transfer efficiency plays an important role in the removal of As(III) by ZVI. A diffusion-limited adsorption model was used to describe the removal of As(III) as the result of adsorption to precipitated iron oxides generated from ZVI corrosion. After an initial period of As(III) rapid adsorption to surface rusts formed during manufacturing and exposure to air, As(III) removal rate is most likely controlled by the rate of iron corrosion and the diffusion of As(III) to adsorption sites in ZVI/iron oxides. |
| Keywords: | Arsenic Ground-water quality Iron Remedial action Sorption Water treatment |