A review on electrochemical treatment of arsenic from aqueous medium

Abstract

The existence of arsenic in nature and its toxicity has gained huge consideration in recent years. The electrochemical methods are getting more attention in the removal of arsenic in over the last few years due to the benefits such as in-situ oxidation, less sludge production and high efficiency with low-cost measures than the conventional techniques. The electrochemical methods are able to remove both arsenite and arsenate from aqueous solution. The various separation techniques are electrocoagulation, capacitive deionization and oxidative removal techniques namely indirect electrochemical oxidation, anodic oxidation and electro-Fenton/bio electro-Fenton reviewed in detail. Among the separation techniques, the arsenic removal efficiencies by electrocoagulation process are above 90%. Meanwhile, the capacitive deionization, another separation technique is applicable only in low arsenic concentration conditions. Rather, at higher initial concentration, the arsenite and arsenate removal are around 40% and 45% respectively. The prior oxidation of arsenite to arsenate is essential for its effective removal. The complete oxidation of arsenite was observed with indirect electrochemical oxidation, but it is limited to low volume applications. When coupling anodic oxidation with electrocoagulation, almost complete oxidation cum removal of arsenic is achievable. The electro-Fenton/bio electro-Fenton processes are employed as the most eco-friendly and economically viable advanced oxidation process for arsenite toxicity reduction and removal.