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

Previous studies have shown that organic ligands could influence Cr(VI) reduction by aqueous Fe 2+ 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 (Cr 2O 7–) 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 Fe 3+, 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 Cr 2O 3 particles were the product of Cr(VI) reduction. In conclusion, 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.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [1]
  1. China Univ. of Geosciences, Beijing (China)
  2. China Univ. of Geosciences, Beijing (China); Miami Univ., Oxford, OH (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Grant/Contract Number:
AC05-76RL01830; 41630103
Type:
Accepted Manuscript
Journal Name:
Journal of Hazardous Materials
Additional Journal Information:
Journal Volume: 343; Journal Issue: C; Journal ID: ISSN 0304-3894
Publisher:
Elsevier
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES; Citrate; Cr(III)-citrate complex; Cr2O3; Cr(VI) reduction; Nontronite
OSTI Identifier:
1395357

Liu, Xiaolei, Dong, Hailiang, Yang, Xuewei, Kovarik, Libor, Chen, Yu, and Zeng, Qiang. Effects of citrate on hexavalent chromium reduction by structural Fe(II) in nontronite. United States: N. p., Web. doi:10.1016/J.JHAZMAT.2017.09.038.
Liu, Xiaolei, Dong, Hailiang, Yang, Xuewei, Kovarik, Libor, Chen, Yu, & Zeng, Qiang. Effects of citrate on hexavalent chromium reduction by structural Fe(II) in nontronite. United States. doi:10.1016/J.JHAZMAT.2017.09.038.
Liu, Xiaolei, Dong, Hailiang, Yang, Xuewei, Kovarik, Libor, Chen, Yu, and Zeng, Qiang. 2017. "Effects of citrate on hexavalent chromium reduction by structural Fe(II) in nontronite". United States. doi:10.1016/J.JHAZMAT.2017.09.038. https://www.osti.gov/servlets/purl/1395357.
@article{osti_1395357,
title = {Effects of citrate on hexavalent chromium reduction by structural Fe(II) in nontronite},
author = {Liu, Xiaolei and Dong, Hailiang and Yang, Xuewei and Kovarik, Libor and Chen, Yu and Zeng, Qiang},
abstractNote = {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. In conclusion, 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.},
doi = {10.1016/J.JHAZMAT.2017.09.038},
journal = {Journal of Hazardous Materials},
number = C,
volume = 343,
place = {United States},
year = {2017},
month = {9}
}