VB_(12)协同Fe/Cu双金属去除二氯甲烷过程调控与机理  

Synergistic effect of vitamin B_(12) and Fe/Cu bimetal on reduction of dichloromethane: Mechanism study and process control

作　　者：林英杰[1] 张硕[1] 孙力平[1] 邢悦[1] LIN Ying-jie;ZHANG Shuo;SUN Li-ping;XING Yue(School of Environmental and Municipal Engineering, Tianjin Chengjian University, Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin 300384,China)

机构地区：[1]天津城建大学环境与市政工程学院天津市水质科学与技术重点实验室,天津300384

出　　处：《中国环境科学》2016年第9期2650-2657,共8页China Environmental Science

基　　金：国家自然科学基金(51478292)

摘　　要：针对地下水中低卤代烷烃的难修复问题,实验制备了Fe/Cu双金属功能性颗粒,研究其对以二氯甲烷为典型污染物的还原去除效能及强化控制方法.结果表明:维生素B_(12)可有效提升Fe/Cu双金属还原能力,其中Fe/Cu-B_(12)系统对二氯甲烷降解的准一级速率常数(0.444h^(-1))远大于Fe/Cu体系(0.018h^(-1))或Fe-B_(12)体系(0.03h^(-1)),证明Cu和B_(12)协同环境可提升零价铁供电子能力.进一步针对Fe/Cu-B_(12)体系开展了过程控制研究,提炼出Cu负载率5%以及pH9.5的弱碱性条件最有利于促成催化还原脱氯反应,并通过还原产物表征结合动力学响应变化对Cu和B_(12)可能的催化协同机理进行了探讨,推测B_(12)先作为活泼电子受体在Cu^0表面将目标有机物脱氯形成中间体物质,而后迅速分解生成B_(12)和加氢还原的卤代物,整个催化过程是在Fe(电子供体)、Cu和B_(12)三者的协同作用下完成的.Functionalized Fe/Cu bimetallic nanoparticles were prepared in this work for remediation of recalcitrantlow-halogenated alkanes, for which the reducing capacity and process-enhancement control were investigated dealingwith dichloromethane (DCM) as representative contaminant. Results show that vitamin B12 significantly promoted theperformance of Fe/Cu bimetal, since rate constant of DCM-reduction for Fe/Cu-B12system (0.444h-1) exhibited muchhigher than that of Fe/Cu system (0.018h-1) or Fe-B12system (0.03h-1), implying the synergistic effect of Cu and B12onelectron-donating ability of zero-valent iron. Experiments were further conducted for process control, and results showedthat 5% surface Cu-coverage and pH 9.5benefits better the catalytic reduction of DCM. Possible mechanism on catalyticperformance of Fe/Cu-B12 system was discussed referring to analysis on intermediate product as well as reduction kinetics.We speculated that the intermediate was prepared by dechlorination of target organic with B12as an active electronacceptor on surface of Cu0, and then quickly decomposed to B12 and hydrogenated halide, the catalytic process wascompleted under synergistic effects of Fe (electron donor), Cu and B12.

关 键 词：Fe/Cu双金属 维生素B12 二氯甲烷 催化脱氯 

分 类 号：X131.2[环境科学与工程—环境科学]