Department of Energy, Environmental and Chemical Engineering and Center for Materials Innovation, Washington University in St Louis, One Brookings Drive, St Louis, Missouri 63130, United States.
Water Res. 2011 Jan;45(1):384-92. doi: 10.1016/j.watres.2010.08.016. Epub 2010 Aug 17.
Exposure to arsenic through drinking water poses a threat to human health. Electrocoagulation is a water treatment technology that involves electrolytic oxidation of anode materials and in-situ generation of coagulant. The electrochemical generation of coagulant is an alternative to using chemical coagulants, and the process can also oxidize As(III) to As(V). Batch electrocoagulation experiments were performed in the laboratory using iron electrodes. The experiments quantified the effects of pH, initial arsenic concentration and oxidation state, and concentrations of dissolved phosphate, silica and sulfate on the rate and extent of arsenic removal. The iron generated during electrocoagulation precipitated as lepidocrocite (γ-FeOOH), except when dissolved silica was present, and arsenic was removed by adsorption to the lepidocrocite. Arsenic removal was slower at higher pH. When solutions initially contained As(III), a portion of the As(III) was oxidized to As(V) during electrocoagulation. As(V) removal was faster than As(III) removal. The presence of 1 and 4 mg/L phosphate inhibited arsenic removal, while the presence of 5 and 20 mg/L silica or 10 and 50 mg/L sulfate had no significant effect on arsenic removal. For most conditions examined in this study, over 99.9% arsenic removal efficiency was achieved. Electrocoagulation was also highly effective at removing arsenic from drinking water in field trials conducted in a village in Eastern India. By using operation times long enough to produce sufficient iron oxide for removal of both phosphate and arsenate, the performance of the systems in field trials was not inhibited by high phosphate concentrations.
饮用水中砷的暴露对人类健康构成威胁。电凝聚是一种水处理技术，涉及阳极材料的电解氧化和原位生成混凝剂。电化学生成混凝剂是替代使用化学混凝剂的一种方法，该过程还可以将 As(III)氧化为 As(V)。在实验室中使用铁电极进行了批量电凝聚实验。实验量化了 pH 值、初始砷浓度和氧化态、溶解磷酸盐、硅和硫酸盐浓度对砷去除率和去除程度的影响。电凝聚过程中生成的铁以纤铁矿（γ-FeOOH）的形式沉淀，除非存在溶解的硅，并且砷通过吸附到纤铁矿上来去除。在较高 pH 值下，砷的去除速度较慢。当溶液最初含有 As(III)时，一部分 As(III)在电凝聚过程中被氧化为 As(V)。As(V)的去除速度快于 As(III)的去除速度。1 和 4 mg/L 磷酸盐的存在抑制了砷的去除，而 5 和 20 mg/L 硅或 10 和 50 mg/L 硫酸盐的存在对砷的去除没有显著影响。在本研究中检查的大多数条件下，砷的去除效率超过 99.9%。电凝聚在印度东部一个村庄进行的现场试验中也非常有效地去除饮用水中的砷。通过使用足够长的操作时间来产生足够的氧化铁以去除磷酸盐和砷酸盐，系统在现场试验中的性能不会受到高磷酸盐浓度的抑制。
