纳米零价铁和过氧化钙联合降解土壤淋洗废液的α-HCH  

Degradation of α-HCH in Soil Washing Solutions with nZVI and CaO_2

作　　者：姚静波 周杰 王明新 荀志祥 薛金娟 YAO Jing-bo;ZHOU Jie;WANG Ming-xin;XUN Zhi-xiang;XUE Jin-juan(College of Environmental ＆ Safety Engineering,Changzhou University)

机构地区：[1]常州大学环境与安全工程学院,常州213164

出　　处：《环境科学》2018年第11期5142-5150,共9页Environmental Science

基　　金：国家自然科学基金项目(41641032;41772240);江苏省"六大人才高峰"培养对象项目(JNHB-003);江苏省高校"青蓝工程"项目

摘　　要：采用纳米零价铁(nZVI)和过氧化钙(CaO_2)组成非均相类芬顿试剂降解土壤淋洗废液中的α-HCH,研究其降解效能及机制.结果表明,nZVI/CaO_2可在较广的pH范围内有效降解α-HCH,当nZVI和CaO_2的投加量为1 g·L^(-1),pH值为5时降解率可达93. 23%. nZVI和CaO_2单独或联合处理α-HCH过程均呈准一级反应动力学模式,联合处理的反应速率常数大于单独处理之和,表明两者联合降解α-HCH具有较好的协同作用.自由基淬灭实验发现,超氧自由基对降解α-HCH的贡献率远大于羟基自由基. nZVI/CaO_2降解α-HCH的中间产物主要是三氯苯和氯苯,其中三氯苯呈先急剧上升后迅速降解趋势,氯苯含量较低且变化较小,因此推测α-HCH主要降解途径是先还原为三氯苯,再继续还原为氯苯或矿化为二氧化碳和水.Nano zerovalent iron（ nZVI） and CaO2 were used to construct a heterogeneous Fenton-like system to degrade α-hexachlorocyclohexane（ α-HCH） in soil solution,and the degradation efficiency and mechanism were investigated. The results showed that nZVI/CaO2 can degrade α-HCH in an extensive pH range. When the dosage of nZVI and CaO2 was 1 g·L^-1 and pH was 5,the degradation rate of α-HCH reached 93. 23%. The degradation process of nZVI,CaO2,and nZVI/CaO2 treatments accorded with the first-order reaction kinetics model. The reaction rate constant of nZVI/CaO2 was greater than the sum of individual treatments,showing that nZVI/CaO2 has a synergistic effect on the degradation of α-HCH. Through quenching free radical experiments,the contribution rate of superoxide radicals was shown to be greater than that of hydroxyl radicals. Intermediates,including trichlorobenzene and chlorobenzene,were detected. The content of trichlorobenzene showed a sharp increase initially,and then decreased quickly. The chlorobenzene content was low and showed little change. The α-HCH in the soil washing solution was first reduced to trichlorobenzene,which was further reduced to chlorobenzene or mineralized into CO2 and water directly.

关 键 词：土壤 纳米零价铁(nZVI) 过氧化钙 α-HCH 淋洗 类芬顿 

分 类 号：X53[环境科学与工程—环境工程]