氯代有机污染物辐照脱氯的研究进展

Dechlorination progress of chlorinated organic pollutants degraded by use of ionizing radiation in aqueous solutions

本工作对电离辐射引发的典型氯代有机污染物的脱氯降解机理进行了综述,重点回顾了氯酚、多氯联苯、三氯乙烯和四氯乙烯辐照脱氯降解的研究现状。氯酚在氧化条件下与羟基自由基(·OH)反应首先形成·OH加成物,然后逐步脱氯;在还原条件下水合电子(e_(aq)^-)与氯酚直接发生选择性反应脱氯,生成苯酚和氯离子。多氯联苯在有机溶剂中的辐照降解反应主要通过链式反应逐渐脱去其中的氯原子,反应的最终产物是氯离子和联苯。三氯乙烯(TCE)和四氯乙烯(PCE)在氧化条件下与羟基自由基(·OH)反应,主要产物有CO_2、HCOOH和HCl等。与氧化途径相比,氯代有机物的辐照还原脱氯具有降解效率高、产物单纯、剂量小等优势。

Kinetics and mechanisms of dechlorination of chlorinated organic pollutants induced by ionizing radiation were described in this article. The progress on the dechlorination of chlorophenols, polychlorinated biphenyl trichloroethylene, and perchloroethylen involved in radiolysis was also reviewed. In oxidative condition, hydroxyl radical （.OH） would attack chlorophenol to form .OH-adducts, which could be dechlorinated gradually. However, chlorophenol can be directly reduced by hydrated electron（eaq） to release C1-. It was found that radiolytical degrada- tion of polychlorinated biphenyls in organic solvent would release chlorine atoms gradually by chain reactions and the final products were C1- and biphenyl. Trichloroethylene and tetrachloroethylene mainly reacted with .OH with the final products of CO2, HCOOH and HCl. As conclusion, the reductive dechlorination of chlorinated organic pollutants possesses advantages of high degradation efficiency, simple products and relatively low radiation dose compared with the oxidation methods.