铁基双金属强化降解地下水中四氯化碳

Enhanced degradation of carbon tetrachloride with iron-based bimetallic particles in groundwater

采用沉积置换法制备了微米级的Ni-Fe、Cu-Fe、Ag-Fe双金属颗粒,应用扫描电镜(SEM)、X射线光电子能谱(XPS)分析了其表面特征,考察了负载金属类型、金属负载量对铁基双金属降解四氯化碳(CCl4)的影响.结果表明:Ni、Cu、Ag等催化金属非均匀地负载在铁基体上,双金属颗粒表面发生了氧化.CCl4的降解速率对催化金属的负载量比较敏感,双金属体系Ni、Cu、Ag的适宜负载量分别为1.0wt%、0.8wt%和0.4wt%.CCl4在双金属体系中的降解途径为零价铁颗粒表面的直接还原及催化金属表面的催化加氢还原,以催化加氢还原为主.Ni-Fe、Cu-Fe、Ag-Fe对CCl4的还原降解速率大小顺序与其电偶电池电动势的大小顺序一致,即Ag-Fe对CCl4的降解速率最快,Cu-Fe次之,Ni-Fe最慢.

Micro-scale bimetallic Ni-Fe,Cu-Fe,Ag-Fe particles were synthesized by displacement plating.The structures were characterized with scanning electron microscope(SEM)and X-ray photoelectron spectroscopy(XPS).The SEM/XPS results showed Ni,Cu,Ag were non-uniformly deposited on the iron matrix,and the surface of the bimetallic particles were oxidized.The variation of CCl4 degradation rate was rather sensitive with the loading ratio of catalytic metal.The suitable loading ratios of Ni,Cu and Ag in Ni-Fe,Cu-Fe and Ag-Fe bimetal were 1.0wt%,0.8wt%and 0.4wt%respectively.The CCl4 degradation pathways in the bimetallic system mainly included direct reduction on zero-valent iron surface and catalytic hydrogenation reduction on catalytic metal surface.Fe-Ag achieved the highest CCl4 degradation efficiency among the tested bimetals,followed by Cu-Fe and Ni-Fe.