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Energy-Efficient Electrochemical Strategy for the Oxidative Sequestration of As(III) in Synthesized Anoxic Groundwater

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journal contribution
posted on 24.05.2018, 00:00 by Bo Jiang, Shuaishuai Xin, Yijie Liu, Congcong Nin, Xuejun Bi, Jianliang Xue
In this study, a wave rectified alternating current (RAC) electrocoagulation process was developed for the oxidative sequestration of As­(III) via simultaneous generating Fe­(II) and O2 in the synthesized anoxic groundwater. The optimal TFe‑anode/TMMO‑anode:Tpower‑off ratio (T is the time-taken in corresponding stage) and reaction period for As­(III) sequestration were 1:2:1 and 24 s, respectively. Elevating electric current applied on the alternate iron/MMO anodes (30–50 mA) and solution pH (6.0–9.0) promoted As­(III) sequestration, whereas the presence of HCO3 and PO43– deteriorated As­(III) sequestration. The intermediate Fe­(IV) primarily accounted for the oxidation of As­(III) to As­(V), which can be readily sequestrated by the freshly generated Fe­(III) (oxyhydr)­oxides. The energy required for As­(III) sequestration in the RAC electrocoagulation process was only 0.11 kW·h m–3, which is much less than those in the traditional DC/AC electrocoagulation processes. Generally, this study offers an energy-efficient strategy to improve access to safe groundwater for millions of people.