School of Environment , Jinan University , Guangzhou 510632 , China.
Department of Plant and Environmental Sciences, Faculty of Life Sciences , University of Copenhagen , Thorvaldsensvej 40 , DK-1871 Frederiksberg C , Denmark.
Environ Sci Technol. 2018 Jul 17;52(14):7876-7883. doi: 10.1021/acs.est.8b02020. Epub 2018 Jun 29.
Layered Fe-Fe hydroxide chloride (chloride green rust, GR) has high reactivity toward reducible pollutants such as chlorinated solvents. However, this reactive solid is prone to dissolution, and hence loss of reactivity, during storage and handling. In this study, adsorption of silicate (Si) to GR was tested for its ability to minimize GR dissolution and to inhibit reduction of carbon tetrachloride (CT). Silicate adsorbed with high affinity to GR yielding a sorption maximum of 0.026 g of Si/g of GR. In the absence of Si, the pseudo-first-order rate constant for CT dehalogenation by GR was 2.1 h, demonstrating very high reactivity of GR but with substantial Fe dissolution up to 2.5 mM. When Si was adsorbed to GR, CT dehalogenation was blocked and Fe dissolution extent was reduced by a factor of 28. The addition of glycine (Gly) was tested for reactivation of the Si-blocked GR for CT dehalogenation. At 30 mM Gly, partial reactivation of the GR was observed with pseudo-first-order rate constant for CT reduction of 0.075 h. This blockage and reactivation of GR reactivity demonstrates that it is possible to design a switch for GR to control its stability and reactivity under anoxic conditions.
层状的 Fe-Fe 氢氧化物氯（氯化绿锈，GR）对可还原污染物如氯化溶剂具有很高的反应活性。然而，这种反应性固体在储存和处理过程中容易溶解，从而失去活性。在这项研究中，测试了硅酸盐（Si）对 GR 的吸附能力，以确定其最小化 GR 溶解和抑制四氯化碳（CT）还原的能力。硅酸钠与 GR 具有高亲和力，最大吸附量为 0.026 g Si/g GR。在没有 Si 的情况下，GR 还原 CT 的假一级速率常数为 2.1 h，表明 GR 具有很高的反应活性，但 Fe 溶解程度高达 2.5 mM。当 Si 被吸附到 GR 上时，CT 脱卤反应被阻断，Fe 溶解程度降低了 28 倍。测试了添加甘氨酸（Gly）以重新激活被 Si 封锁的 GR 进行 CT 脱卤反应。在 30 mM Gly 的条件下，观察到 GR 的部分重新激活，CT 还原的假一级速率常数为 0.075 h。这种对 GR 反应性的阻断和再激活表明，可以设计一种开关来控制 GR 在缺氧条件下的稳定性和反应性。
