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Removal of Perchlorate and Chlorate in Aquatic SystemsUsing Integrated Technologies
Citation:
Srinivasan, R., G. Sorial, AND E. SAHLE-DEMESSIE. Removal of Perchlorate and Chlorate in Aquatic SystemsUsing Integrated Technologies. ENVIRONMENTAL ENGINEERING SCIENCE. Mary Ann Liebert, Inc., Larchmont, NY, 26(11):1661 - 1671, (2009).
Impact/Purpose:
To inform the public.
Description:
Because of its extremely low concentrations and strong resistance to most treatment technologies, perchlorate has become one of the biggest challenges currently being faced by the drinking water industry. Few studies have looked at electrochemical reduction of aqueous perchlorate, and there is also limited data in the literature on removal of chlorate in water. This is the first attempt to develop an integrated method for removal of perchlorate and chlorate in water by combining zero-valent iron (Fe0) and electrochemical reduction. However, use of Fe0 in electrochemical process did not produce expected results, as high pH and the presence of hydrogen gas rendered the Fe0 ineffective for any perchlorate reduction. Electrochemical experiments for perchlorate reduction with electrodes such as nickel and carbon in the presence of cobalt-based catalysts did result in reaction rate constants that were three to five times higher those achieved with Fe0. However, these rates are still too slow for any practical consideration. Surface characteristics of iron were studied to determine reasons for this reduced capacity. Batch experiments and electrochemical experiments were conducted to better understand reduction of chlorate and effects of various process parameters on chlorate reduction kinetics. As expected, reduction rates for chlorate achieved with Fe0 were significantly higher when compared with perchlorate. Also, reaction kinetics associated with electrochemical reduction of chlorate were comparable to that observed with Fe0, especially at low pH. Electrolyte ionic strength and pH were found to be the most important factors influencing chlorate reduction. Results of this study could be used to optimize complete removal of perchlorate and chlorate in water by electrochemical reduction.
