title: Coupled Effect of Ferrous Ion and Oxygen on the Electron Selectivity of Zerovalent Iron for Selenate Sequestration.
abstract: Although the electron selectivity (ES) of zerovalent iron (ZVI) for target contaminant and its utilization ratio (UR) decide the removal capacity of ZVI, little effort has been made to improve them. Taking selenate [Se(VI)] as a target contaminant, this study investigated the coupled influence of aeration gas and Fe(II) on the ES and UR of ZVI. Oxygen was necessary for effective removal of Se(VI) by ZVI without Fe(II) addition. Due to the application of 1.0 mM Fe(II), the ES of ZVI was increased from 3.2-3.6% to 6.2-6.8% and the UR of ZVI was improved by 5.0-19.4% under aerobic conditions, which resulted in a 100-180% increase in the Se(VI) removal capacity by ZVI. Se(VI) reduction by Fe0was a heterogeneous redox reaction, and the enrichment of Se(VI) on ZVI surface was the first step of electron transfer from Fe0core to Se(VI). Oxygen promoted the generation of iron (hydr)oxides, which facilitated the enrichment of Se(VI) on the ZVI particle surface. Therefore, the high oxygen fraction (25-50%) in the purging gas resulted in only a slight decrease in the ES of ZVI. Fe(II) addition resulted in a pH drop and promoted the generation of lepidocrocite and magnetite, which benefited Se(VI) adsorption and the following electron transfer from underlying Fe0to surface-located Se(VI).
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Shanghai 200092, P.R. China.
authors.forename: Hejie
authors.initials: H
authors.lastname: Qin
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Shanghai 200092, P.R. China.
authors.forename: Jinxiang
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Shanghai 200092, P.R. China.
authors.forename: Hongyi
authors.initials: H
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University , Nanjing 210023, Jiangsu, P.R. China.
authors.forename: Bingcai
authors.initials: B
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environment, Nanjing University , Nanjing 210023, Jiangsu, P.R. China.
authors.forename: Weiming
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Shanghai 200092, P.R. China.|Guangzhou Key Laboratory of Environmental Exposure and Health, School of Environment, Jinan University , Guangzhou 510632, Guandong, P.R. China.
authors.forename: Xiaohong
authors.identifier: http://orcid.org/0000-0001-5296-423X
authors.initials: X
authors.lastname: Guan
mesh_terms: D004583:Electrons; D007501:Iron; D010084:Oxidation-Reduction; D010100:Oxygen; D064586:Selenic Acid; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical; D007501:Iron; D064586:Selenic Acid; D010100:Oxygen