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预处理方式对氧化-还原联合技术修复硝基苯污染地下水的影响
夏 甫, 杨 昱, 万硕阳, 郜普闯, 韩旭, 姜永海, 徐祥健
中国环境科学研究院
摘要:
为了探究氧化与还原预处理对氧化-还原联合技术修复硝基苯污染地下水的影响,选取2,4-二硝基甲苯(2,4-DNT)为研究对象,构建过硫酸盐/铁炭修复技术体系,分别设置以过硫酸盐作为氧化预处理联合以铁炭作为还原后处理的试验槽和以铁炭作为还原预处理联合以过硫酸盐作为氧化后处理的试验槽,对比研究构建的氧化-还原联合系统中氧化与还原预处理方式的不同对2,4-DNT去除机制的影响。结果表明:①过硫酸盐氧化材料填充位置显著影响试验槽pH和氧化还原电位(ORP)的变化,在运行周期5 孔隙体积 (PV)内,pH可显著增至11左右,ORP值达到最高。②在运行周期5 PV 内,氧化填充层过硫酸根浓度和还原填充层Fe2+浓度均显著降低。③在运行周期5 PV 内,以过硫酸盐作为氧化预处理联合以铁炭作为还原后处理的协同技术体系对2,4-DNT的去除效果显著降低,以铁炭作为还原预处理联合以过硫酸盐作为氧化后处理的协同技术体系对2,4-DNT去除效率维持在100%。④通过液相-质谱联用技术,识别构建的氧化-还原联合技术体系内2,4-DNT降解的主要中间产物,同时结合铁炭微电解还原机制和过硫酸盐氧化机制提出了协同处理机制和可能降解路径。研究显示,还原预处理更有利于氧化-还原联合技术对地下水中2,4-DNT的去除,可为有效地处理硝基苯化合物污染地下水提供理论支撑。
关键词:  氧化预处理  还原预处理  2,4-二硝基甲苯  中间产物  降解机制
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基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
Influence of Pre-treatment Methods on Remediation of Nitrobenzene Contaminated Groundwater by Combined Oxidation-reduction Techniques
杨 昱, WAN Shuoyang, GAO Puchuang, HAN Xu, JIANG Yonghai, 徐祥健
Chinese Research Academy of Environmental Sciences
Abstract:
In order to investigate the effects of the oxidation and reduction pre-treatment on the combined oxidation-reduction techniques in the remediation of nitrobenzene contaminated groundwater, 2,4-dinitrotoluene(2,4-DNT)was chosen as the target contaminant and the persulfate-iron-carbon remediation technology system was constructed. Specifically, the large experimental troughs of persulfate as oxidation pre-treatment combined with subsequent reduction post-treatment of iron-carbon mixture material and iron-carbon mixture material as reduction pre-treatment combined with subsequent oxidation post-treatment treatment of persulfate were set up. The effects of oxidation and reduction pre-treatment on 2,4-DNT removal mechanism in the combined oxidation-reduction system were compared and studied. The results showed the filling position of persulfate material significantly affected the changes of pH and oxidation-reduction potential (ORP) in large experimental troughs. pH could be significantly increased to about 11, and ORP value reached the highest in the 5 pore volumes (PV). Within 5 PV, the concentration of persulfate in the oxidized packed layer and the concentration of Fe2+ in the reduced packed layer decreased significantly. Within 5 PV, the removal efficiency of 2,4-DNT in the large experimental trough of persulfate as oxidation pre-treatment combined with subsequent reduction post-treatment of iron-carbon mixture material was significantly reduced, whereas that in the large experimental trough of iron-carbon mixture material as reduction pre-treatment combined with subsequent oxidation post-treatment treatment of persulfate was maintained at 100%. The main intermediates of 2,4-DNT degradation in the combined oxidation-reduction techniques system were identified by liquid chromatograph mass spectrometer (LC-MS). In combination with the iron-carbon micro-electrolysis reduction mechanism and persulfate oxidation mechanism, the collaborative treatment mechanism and possible degradation paths were proposed. Our results showed that the experimental trough of iron-carbon mixture material as reduction pre-treatment combined with subsequent oxidation post-treatment treatment of persulfate was more beneficial to the 2,4-DNT removal in the combined oxidation-reduction remediation system, which provided theoretical support for the effective treatment of nitrobenzene contaminated groundwater.
Key words:  Oxidation pre-treatment  Reduction pre-treatment  2,4-DNT  Intermediates  Degradation mechanisms