Fundamental study on efficiency and safety of washing-reagent-injection as a remediation technique for soil and groundwater pollution

研究了表面活性剂和高分子量有机化合物共存对三氯乙烯（TCE）水溶性的影响、TCE在玻璃球填充柱中的重力迁移行为以及零价铁粉对TCE的还原脱氯分解。试剂类型和浓度对TCE在玻璃珠填充柱中的溶解度和迁移行为的影响是相互影响的。几种表面活性剂显著提高了TCE的溶解度，但一些表面活性剂和高分子量有机化合物对TCE的溶解度没有影响。未稀释的TCE在洗涤试剂饱和柱中的迁移行为对于测试的化学物质有很大的不同。一些表面活性剂在很大的浓度范围内引入了重力驱动的快速迁移。在脱氯反应过程中，TCE的量减少，并观察到顺式-1,2-二氯乙烯的形成。当溶液中不含添加剂时，TCE和零价铁浓度的分解是一级的。添加添加剂时，TCE的分解速率低于不添加添加剂时的分解速率：阳离子表面活性剂十六烷基三甲基溴化铵的分解速率常数降低了0.7倍；阴离子表面活性剂正十二烷基苯磺酸钠、正十二烷基硫酸钠和正十二烷基磺酸钠以及高分子量有机化合物可溶性淀粉、β-环糊精和聚乙烯乙二醇6000的系数为0.5；月桂酸钠和非离子表面活性剂Triton X-100、Tween 20、Tween 60、brij35和brij58的比例为0.2。结果表明，洗涤试剂注射法既有优点，也有缺点。建议对几个因素进行彻底评估对于实际使用该技术的重要性

To learn efficiency and safety of washing-reagent-injection, a new soil/groundwater remediation technique for chlorinated organic solvent pollution, the effects of coexisting surfactants and high-molecular-weight organic compounds on the water solubility of trichloroethylene (TCE), the gravity-driven migration behavior of TCE in a glass-bead-packed column, and the reductive dechlorination decomposition of TCE with zerovalent iron powder were investigated.The effect of reagent type and concentration on TCE solubility and migration behavior in glass-bead-packed columns appeared severally each other. Several of the surfactants drastically increased the solubility of TCE, but some surfactants and the high-molecular-weight organic compounds had no effect on TCE solubility. The migration behaviors of undiluted TCE in the washing-reagent-saturated columns differed substantially for the tested chemicals. Some of the surfactants introduced rapid gravity-driven migration over a wide range of con … More centrations.During the dechlorination reaction, the amount of TCE decreased, and the formation of cis-1,2-dichloroethylene was observed. The decomposition of TCE was found to be first order with respect to the-TCE and zerovalent iron concentrations when the solution contained no additives. The rates of decomposition of TCE in the presence of the additives were lower than the rate in the absence of the additives: the rate constant was reduced by a factor of 0.7 for the cationic surfactant cetyltrimethylammonium bromide; by a factor of 0.5 for the anionic surfactants sodium n-dodecylbenzenesulfonate, sodium n-dodecylsulfate, and sodium n-dodecanesulfonate and for the high-molecular-weight organic compounds soluble starch, β-cyclodextrin, and polyethyleneglycol 6000;and by a factor of 0.2 for sodium laurate and the nonionic surfactants Triton X-100,Tween 20,Tween 60,Brij 35,and Brij 58.The results indicate that the washing-reagent-injection method contains several advantages and disadvantages. Importance of thoroughly assessment for several factors is suggested for the practical use of this technique Less