New Paper: Two Novel Routes of Contaminant Degradation by Zerovalent Iron
PGT
So much work has been done on reduction of chlorinated solvents and nitro aromatics by zerovalent iron that it overshadows other pathways by which zerovalent iron might degrade organic contaminants. Here we provide evidence for two overlooked pathways using 2-chlorophenylethanol (CPE) as model/probe contaminant. CPE is chlorohydrin, and might serve as a model for other halohydrin contaminants.
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Chen, S., D. Fan, and P. G. Tratnyek. 2014. Novel contaminant transformation pathways by abiotic reductants. Environmental Science & Technology Letters 1(10): 432-436.
Environmentally relevant abiotic reductants, such as zerovalent iron (ZVI) and minerals containing divalent iron (DVI), react predominantly by electron-transfer mechanisms with a variety of contaminant and probe compounds. Other reduction mechanisms involving activated forms of hydrogen (Hads or H•) have been suggested, but most evidence for these is only from systems containing noble metals that catalyze hydrogen activation (e.g., Pd). Here, 2-chlorophenylethanol and relatives of this aromatic halohydrin are used as probe compounds to show that ZVI can affect reduction by several novel pathways that are not observed with DVI minerals. These pathways include dechlorination by intramolecular nucleophilic substitution and epoxide ring opening by reduction. The former appears to be catalyzed by hydroxyl groups associated with oxides on actively corroding ZVI, and the latter can arise from hydride transfer (from NaBH4) or electron transfer (from ZVI).