Effects of abiotic mineral transformation of FeS on the dynamic immobilization of Cr(VI) in oxic aquatic environments

Tao Wang; Dongye Zhao; Junyong Liu; Tong Zhang; Xizhi Wang; Ting Liu; Sheng Wang; Gaobin Liu; Bin Liu; Yuanyuan Liu

doi:10.1016/j.scitotenv.2023.164991

Effects of abiotic mineral transformation of FeS on the dynamic immobilization of Cr(VI) in oxic aquatic environments

Sci Total Environ. 2023 Oct 10:894:164991. doi: 10.1016/j.scitotenv.2023.164991. Epub 2023 Jun 19.

Authors

Tao Wang¹, Dongye Zhao², Junyong Liu¹, Tong Zhang¹, Xizhi Wang¹, Ting Liu¹, Sheng Wang¹, Gaobin Liu³, Bin Liu¹, Yuanyuan Liu⁴

Affiliations

¹ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment of Ministry of Education, Chongqing University, Chongqing 400044, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China.
² Department of Civil, Construction and Environmental Engineering, San Diego State University, San Diego, CA 92182-1324, USA.
³ Department of Applied Physics, Chongqing University, Chongqing 400044, China.
⁴ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment of Ministry of Education, Chongqing University, Chongqing 400044, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China. Electronic address: Liuyuanyuan@cqu.edu.cn.

PMID: 37343854
DOI: 10.1016/j.scitotenv.2023.164991

Abstract

Iron sulfide (FeS) can reductively convert soluble Cr(VI) into insoluble Cr(III) under anoxic conditions. However, the fate and transformation of FeS and the stability of immobilized Cr under various oxic environmental conditions are poorly understood. The results show that FeS transforms into pyrrhotite and pyrite intermediates principally and finally lepidocrocite and elemental sulfur, accordingly accounting for 66.1% and 33.9%. Temperature, fulvic acid as natural organic matter and coexisted ions of nitrate, bicarbonate, and calcium affect the evolution of FeS insignificantly. Transformation of FeS involves surface-mediated oxidation of FeS solids, and minor proton-promoted dissolution and oxidation, accompanying synergistic oxidation of Fe(II) and S(-II). Cr(VI) removal performances of oxygenated FeS with increasing duration showed a rise-fall trend. Reduction dominates Cr(VI) uptake first and finally, sorption prevails with the gradual FeS oxygenation. Cr(VI) removal correlates linearly with Cr(VI) reduction, and the reduced Cr species can be predicted based on the known Cr(VI) removal performance. As the FeS oxygenation time increases, newly generated pyrite improves Cr(VI) reduction and removal, and then a decreasing ability to reduce Cr(VI) causes a drop in Cr(VI) removal. These findings provide new insight into the oxidative transformation of FeS in oxic aquatic environments and its impact on Cr(VI) levels.

Keywords: Chromium contamination; Groundwater and soil remediation; Iron sulfides; Mineral transformation; Oxygenation.