Effects of citrate on hexavalent chromium reduction by structural Fe(II) in nontronite

JOURNAL OF HAZARDOUS MATERIALS

卷:343

Article

Liu, Xiaolei^1,2  Dong, Hailiang^1,2,3  Yang, Xuewei^1,2  Kovarik, Libor⁴  Chen, Yu^1,2  Zeng, Qiang^1,2 

[1] China Univ Geosci, State Key Lab Biogeol & Environm Geol, Beijing 100083, Peoples R China

[2] China Univ Geosci, Sch Earth Sci & Resources, Beijing 100083, Peoples R China

[3] Miami Univ, Dept Geol & Environm Earth Sci, Oxford, OH 45056 USA

[4] Pacific Northwest Natl Lab, Environm Mol Sci Lab, Richland, WA 99354 USA

关键词: Citrate;    Cr(III)-citrate complex;    Cr2O3;    Cr(VI) reduction;    Nontronite;   

DOI  :  10.1016/j.jhazmat.2017.09.038

来源: Elsevier

【 摘 要 】

Previous studies have shown that organic ligands could influence Cr(VI) reduction by aqueous Fe2+ and pyrite. In this study, the effects of citrate on Cr(VI) reduction by structural Fe(II) in nontronite (NAu-2) were investigated at pH 6. Our results showed that the presence of citrate decreased the rate but increased the amount of Cr(VI) reduction. The decreased rate was likely due to competitive sorption of citrate and anionic dichromate (Cr2O7-) to NAu-2 surface sites, because sorption of dichromate appeared to be the first step for subsequent Cr(VI) reduction. The increased amount of Cr(VI) reduction was likely because citrate served as an additional electron donor to reduce Cr(VI) through ligand-metal electron transfer in the presence of soluble Fe3+, which was possibly derived from dissolution of reduced NAu-2. Soluble Cr(III)-citrate complex was a possible form of reduced Cr(VI) when citrate was present. Without citrate, nanometer-sized Cr2O3 particles were the product of Cr(VI) reduction. Our study highlights the importance of citrate on Cr(VI) reduction and immobilization when iron-rich smectite is applied to treat Cr(VI) contaminant in organic carbon rich environments. (C) 2017 Elsevier B.V. All rights reserved.

【 授权许可】

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