EK/Fe^0-PRB联合修复实际砷污染土壤的协同机制  

Synergistic effects of electrokinetics process coupled with zero-valent iron permeable reaction barrier in remediation of arsenic-contaminated soil

作　　者：纪冬丽 张竞[2] 孟凡生[3] 王业耀[4] JI Dongli;ZHANG Jing;MENG Fansheng;WANG Yeyao(School of Environmental and Municipal Engineering,Tianjin Urban Construction College,Tianjin300384,China;Tianjin Geological Survey Center,Tianjin300170,China;State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences,Beijing100012,China;China National Environmental Monitoring Station,Beijing100012,China)

机构地区：[1]天津城建大学环境与市政工程学院,天津300384 [2]天津地质调查中心,天津300170 [3]中国环境科学研究院环境基准与风险评估国家重点实验室水污染控制技术研究中心,北京100012 [4]中国环境监测总站,北京100012

出　　处：《化工学报》2018年第12期5276-5282,共7页CIESC Journal

基　　金：天津市教委科研计划(2018KJ170)~~

摘　　要：以我国某矿区砷污染土壤为研究对象,采用EK/Fe^0-PRB联合修复工艺去除土壤中的砷,考察了土壤含水率及增强试剂对砷去除的影响,分析了修复前后土壤中砷的迁移分布及砷价态分布变化,并借助X射线光电子能谱(XPS)对修复前后PRB填料Fe^0进行了表征分析,探讨了EK/PRB修复砷污染的协同机制。结果表明,在EK/PRB联合修复过程中,EK去除作用所占比例为22%～43%,而PRB的去除作用所占比例为52%～71%,以PRB的去除作用为主;未添加增强试剂时,阳极液砷收集含量明显高于阴极液砷收集含量,电动去除机制主要为电迁移作用,添加增强试剂后,阴极液砷收集含量所占比例明显升高;EK/PRB修复后,As(Ⅴ)和As(Ⅲ)在土壤、电极液、PRB中的含量比例基本没有变化,As(Ⅴ)含量比例略微升高,即处理之后土壤中的五价砷并不会经氧化还原作用而转变成毒性较高的三价砷;反应后Fe^0表面存在As(Ⅲ)和As(Ⅴ),未发现As(0)的存在,因此砷在PRB中仅通过铁表面氧化物的吸附作用而去除。The remediation of arsenic polluted soil from a mining area in China using the electrokinetics process coupled with zero-valent iron permeable reaction barrier was researched.The influence of soil moisture content and enhancement reagents on arsenic removal was investigated.The changes of distribution and valence state of arsenic before and after the remediation were analyzed.In addition,surface features of the fresh and used zero-valent iron were characterized by X-ray photoelectron spectroscopy(XPS).Then synergistic effects of EK/PRB in the remediation of arsenic-contaminated soil was discussed.The results showed that in the EK/PRB remediation process,fraction of the EK removal mechanism was22%to43%,while fraction of the PRB removal mechanism was52%to71%,so the PRB process was dominate.When the enhancement reagents was absent,arsenic mainly tends to move toward the anolyte,which indicated the mainly removal mechanisms was electromigration.However,when the enhancement reagents was added,the proportion of arsenic collected from the cathode solution was significantly increased.After EK/PRB remediation,the percentage content of As(Ⅴ)and As(Ⅲ)in soil,electrode liquid and PRB had no substantial changes,only the content ratio of As(Ⅴ)raised slightly.Pentavalent arsenic will not be reduced into trivalent arsenic with higher toxicity.There were no As(0)but As(Ⅲ)and As(Ⅴ)on the surface of the used Fe0.Therefore,arsenic was removed in PRB only through adsorption of the iron surface oxides.

关 键 词：砷 污染土壤 电动修复 PRB 协同机制 

分 类 号：X53[环境科学与工程—环境工程]