Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen , Thorvaldsensvej 40, Frederiksberg C, DK-1871, Denmark.
Environ Sci Technol. 2017 Mar 21;51(6):3445-3452. doi: 10.1021/acs.est.6b06244. Epub 2017 Mar 13.
Layered Fe-Fe hydroxides (green rusts, GRs) are promising reactants for reductive dechlorination of chlorinated solvents due to high reaction rates and the opportunity to inject reactive slurries of the compounds into contaminant plumes. However, it is necessary to develop strategies that reduce the formation of toxic byproducts such as chloroform (CF). In this study, carbon tetrachloride (CT) dehalogenation by the chloride form of GR (GR) was tested in the presence of glycine (GLY) and other selected amino acids. GLY, alanine (ALA), and serine (SER) all resulted in remarkable suppression of CF formation with only ∼10% of CF recovery while sarcosine (SAR) showed insignificant effects. For two nonamino acid buffers, TRIS had little effect while HEPES resulted in a 40 times lower rate constant compared to experiments in which no buffer was added. The Fe complexing properties of the amino acids and buffers caused variable extents of GR dissolution which was linearly correlated with CF suppression and dehalogenation rate. We hypothesize that the CF suppression seen for amino acids is caused by stabilization of carbene intermediates via the carbonyl group. Different effects on CF suppression and CT dehalogenation rate were expected because of the different structural and chemical properties of the amino acids.
层状 Fe-Fe 氢氧化物（绿色锈，GRs）由于反应速率高，并且有机会将化合物的反应性泥浆注入污染物羽流中，因此是还原脱氯氯化溶剂的有前途的反应物。然而，有必要开发减少有毒副产物（如三氯甲烷（CF））形成的策略。在这项研究中，在甘氨酸（GLY）和其他选定的氨基酸存在下，测试了 GR（GR）的氯化物形式对四氯化碳（CT）的脱卤作用。GLY、丙氨酸（ALA）和丝氨酸（SER）都导致 CF 形成的显着抑制，仅回收了约 10%的 CF，而肌氨酸（SAR）则没有显着影响。对于两种非氨基酸缓冲液，TRIS 的影响很小，而与未添加缓冲液的实验相比，HEPES 的速率常数低 40 倍。氨基酸和缓冲液的 Fe 络合特性导致 GR 溶解的程度不同，这与 CF 抑制和脱卤速率呈线性相关。我们假设，由于羰基的存在，氨基酸对碳烯中间体的稳定作用导致了 CF 抑制的现象。由于氨基酸的结构和化学性质不同，预计对 CF 抑制和 CT 脱卤速率的影响也不同。
