Fe2+/过碳酸盐催化氧化修复四氯乙烯污染地下水的机理及应用

Mechanism and Application of Perchloroethylene Contaminated Groundwater Remediation by Fe2+/Percarbonate Catalyzed Oxidation

采用Fe^2+催化过碳酸钠(SPC)工艺对四氯乙烯(PCE)污染地下水进行修复,考察了氧化剂、催化剂浓度对PCE降解过程的影响。分别以硝基苯和四氯化碳为HO·探针和还原性自由基探针,证实了Fe^2+/SPC工艺中存在大量的HO·和少量的O2^·-;分别以异丙醇及氯仿为HO·及还原性自由基的清扫剂考察工艺的主体自由基,结果表明Fe^2+/SPC工艺降解PCE的主体自由基为HO.,并通过电子顺磁共振(EPR)试验证实了这一结果。结合实际地下水成分,考察了阴离子(Cl^-、HCO3^-、SO4^2-、NO3^-)及腐植酸(HA)对PCE降解过程的影响,结果表明HCO3^-、Cl^-及HA均对降解过程有抑制作用,而SO4^2-、NO3^-对PCE降解没有显著影响。Cl^-浓度测定结果表明,催化降解过程能使PCE完全脱氯。采用Fe^2+/SPC催化降解工艺修复PCE污染地下水具有较好的应用前景,实际应用中应考虑药剂投加量、阴离子和腐植酸等的影响。

Performance of Fe^2+-sodium percarbonate(SPC)process for the catalyzed oxidation remediation of perchloroethylene(PCE)-contaminated groundwater was investigated.Impact of concentrations of the oxidant and catalyst on the degradation of PCE was analyzed.Based on the results of probe and free radical scavenging tests for HO·and reducing free radicals,it was found that there was considerable amount of HO·and a small amount of O2^·-occurred in the Fe^2+/SPC system,and PCE was degraded mainly by HO·in the oxidation process,which was also proved by the electron paramagnetic resonance(EPR)test.Effects of common constituents in practical groundwater,such as anions including Cl^-,HCO3^-,SO4^2-,and NO3^-,and humic acid(HA),on the Fe^2+/SPC catalyzed oxidation of PCE were evaluated.Results showed that HCO3^-,Cl^-and HA all inhibited the degradation of PCE,while SO4^2-,NO3^-had no significant influence.Determination of Cl^-concentration showed that PCE could be completely dechlorinated by catalytic SPC degradation process.In conclusion,Fe^2+/SPC catalyzed oxidation is a highly promising technique for remediation of PCE-contaminated groundwater,but influence of chemical dosage,anions and HA in groundwater should be carefully considered for its practical application.