Long-Term Fe Transformation Decreases the Adsorption But Enhances the Reduction of Cr(Vi) by Humic Substance-Ferric Iron Coprecipitates

作     者：Wang, Hui Liu, Fengping Zhang, Yankun Gong, Xueying Zhu, Jinqi Tan, Wenbing Yuan, Ying Zhang, Jia Chen, Honghan Xi, Beidou 

作者机构：State Key Laboratory of Environmental Criteria and Risk Assessment State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution Chinese Research Academy of Environmental Sciences Beijing100012 China Beijing Key Laboratory of Water Resources & Environmental Engineering China University of Geosciences Beijing100083 China Chinese Academy for Environmental Planning Beijing100020 China 

出 版 物：《SSRN》 

年 卷 期：2024年

核心收录：

主　　题：Adsorption 

摘      要：Humic substance (HSs)-Fe(III) coprecipitates are widespread in soil and aquifers, undergoing transformation throughout their presence. However, the mechanisms of their transformation, and the influence on the environmental behavior of HSs-Fe(III) coprecipitates remain unclear. Here, the transformation of HS-Fe(III) coprecipitates was simulated to investigate the role in the adsorption and reduction of a hazardous pollutant, Cr(VI). The capacity of HSs-Fe(III) coprecipitates to adsorb/reduce Cr(VI) was found to depend on their structure. In ferrihydrite (Fh)-like coprecipitates, the amorphous Fh transformed into crystalline hematite and goethite, accompanied by a decrease in specific surface area and active sites, thereby decreasing the Cr(VI) adsorption capacity. However, this transformation enhanced the surface catalysis of Fe-containing components, which increased the number of functional groups activated for Cr(VI) reduction. In HSs-like coprecipitates, Fe(III) always served as a cation bridge connecting the HS molecules, but became reduced by the associated HSs. The produced Fe(II) acted as an adsorption-reduction site, driving the increasing reduction of the adsorbed Cr(VI) as the transformation progressed. Our findings emphasize the pivotal role of long-term transformation in boosting the capacity of HSs-Fe(III) coprecipitates to reduce Cr(VI). This insight may open a new avenue for the development of in-situ remediation agents for Cr(VI)-contaminated sites. © 2024, The Authors. All rights reserved.