EVO(乳化油)-Mg(OH)2双功能缓释剂强化修复三氯乙烯污染地下水

氯代烃污染地下水在外加有机质(电子供体)进行强化还原脱氯时，存在有机质消耗快、pH持续降低等影响脱氯效率的问题。利用乳化油(EVO)与胶体氢氧化镁复配的方法，制备了一种兼具电子供体缓释性和OH-缓释性的双功能缓释剂EVO-Mg(OH)2；成功制备了不同EVO∶Mg(OH)2配比的EVO-Mg(OH)2试剂，并对其稳定性、分散性及粒径分布进行了研究；向模拟砂柱中注入不同体积的EVO-Mg(OH)2，考察试剂的迁移性能以及试剂注入对三氯乙烯(TCE)迁移的影响；开展了EVO-Mg(OH)2强化TCE还原脱氯摇瓶实验，考察了该试剂对脱氯效果的影响。结果表明：不同EVO∶Mg(OH)2配比的试剂稳定性及分散性良好，粒径无明显差异；EVO-Mg(OH)2可以有效地在多孔介质中迁移并实现部分滞留；注入量对EVO-Mg(OH)2的迁移性有一定的影响；EVO-Mg(OH)2可以促进TCE溶解和迁移从而减小EVO-Mg(OH)2和TCE之间的传质阻力；EVO-Mg(OH)2能够实现电子供体及OH-的双重缓释，有效促进脱氯微生物的生长，提高TCE的降解速率(k=0.128 d-1)，同时抑制pH的降低(pH=7.5)。

Enhanced remediation of TCE contaminated groundwater by double sustained-release agent of EVO (emulsified vegetable oil)-Mg(OH)2

Reductive dechlorination can be enhanced by the addition of organic substrate (as electron donor) to the chlorinated organic compound contaminated groundwater. However, the dechlorination efficiency can be limited by the rapid consumption of substrates and continuous decline in pH. In this study, the emulsified vegetable oil (EVO) combined with colloidal Mg(OH)2 was used to prepare a bifunctional sustained-release agent of EVO-Mg(OH)2, which could slowly release electrons and OH-. And the EVO-Mg(OH)2 agents with different EVO∶Mg(OH)2 ratios were successfully prepared and their stability, dispersibility and particle size distribution were studied. Then different volumes of EVO-Mg(OH)2 were injected into simulated sand columns to evaluate the migration properties of EVO-Mg(OH)2, and the influence of EVO-Mg(OH)2 injection on the migration of TCE. Flask experiments on enhanced TCE reduction were conducted to investigate the TCE dechlorination efficiency in the presence of EVO-Mg(OH)2. The results showed that the EVO-Mg(OH)2 with different EVO∶Mg(OH)2 ratios had a good stability and dispersibility with no significant difference in particle size. EVO-Mg(OH)2 could effectively migrate and partially retain in the porous media. The injection volumes had an obvious effect on the migration of EVO-Mg(OH)2. In addition, the injection of EVO-Mg(OH)2 significantly enhanced the dissolution and migration of TCE, and reduce the mass transfer resistance between EVO-Mg(OH)2 and TCE. The addition of EVO-Mg(OH)2 could achieve double sustained release of electron donor and OH-, and effectively facilitate the growth of dechlorinating bacteria to increase the dechlorination rate of TCE (k=0.128 d-1), and inhibit the decline of pH (pH=7.5).