Efficient Reductive Dechlorination of Monochloroacetic Acid by Sulfite/UV Process

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• 作者：Xuchun Li ; Jun Ma ; Guifang Liu ; Jingyun Fang ; Siyang Yue ; Yinghong Guan ; Liwei Chen ; Xiaowei Liu
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：July 3, 2012
• 年：2012
• 卷：46
• 期：13
• 页码：7342-7349
• 全文大小：358K
• 年卷期：v.46,no.13(July 3, 2012)
• ISSN：1520-5851

文摘

Most halogenated organic compounds (HOCs) are toxic and persistent, and their efficient destruction is currently a challenge. Here, we proposed a sulfite/UV (253.7 nm) process to eliminate HOCs. Monochloroacetic acid (MCAA) was selected as the target compound and was degraded rapidly in the sulfite/UV process. The degradation kinetics were accelerated proportionally to the increased sulfite concentration, while the significant enhancement by increasing pH only occurred in a pH range of 6.0鈥?.7. The degradation proceeded via a reductive dechlorination mechanism induced by hydrated electron (e_aq^{鈥?/sup>), and complete dechlorination was readily achieved with almost all the chlorine atoms in MCAA released as chloride ions. Mass balance (C and Cl) studies showed that acetate, succinate, sulfoacetate, and chloride ions were the major products, and a degradation pathway was proposed. The dual roles of pH were not only to regulate the S(IV) species distribution but also to control the interconversion between e_aq鈥?/sup> and H鈥?/sup>. Effective quantum efficiency (桅) for the formation of e_aq鈥?/sup> in the process was determined to be 0.116 卤 0.002 mol/einstein. The present study may provide a promising alternative for complete dehalogenation of most HOCs and reductive detoxification of numerous toxicants.}