Antimony isotopic fractionation induced by Sb(V) adsorption on β-MnO2

Bing Wen; Weiqing Zhou; Peng Liu; Yuanzheng Zhang; Xiaocen Jia; Shang Gao; Fan Zhang; Jianwei Zhou; Jianbo Huang

doi:10.1016/j.scitotenv.2024.172972

Antimony isotopic fractionation induced by Sb(V) adsorption on β-MnO₂

Sci Total Environ. 2024 May 10:933:172972. doi: 10.1016/j.scitotenv.2024.172972. Online ahead of print.

Authors

Bing Wen¹, Weiqing Zhou², Peng Liu², Yuanzheng Zhang¹, Xiaocen Jia², Shang Gao¹, Fan Zhang³, Jianwei Zhou⁴, Jianbo Huang⁵

Affiliations

¹ State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, 210042 Nanjing, People's Republic of China.
² School of Environmental Studies, China University of Geosciences, 430074 Wuhan, People's Republic of China.
³ Shanghai Chengtou Huanfu Private Equity Fund Management Co., Ltd., 200120 Shanghai, People's Republic of China.
⁴ School of Environmental Studies, China University of Geosciences, 430074 Wuhan, People's Republic of China; Key Laboratory of Mine Ecological Effects and System Restoration, Ministry of Natural Resources, 100081 Beijing, People's Republic of China. Electronic address: jw.zhou@cug.edu.cn.
⁵ State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Ecology and Environment of China, 210042 Nanjing, People's Republic of China. Electronic address: huangjianbo@nies.org.

PMID: 38735328
DOI: 10.1016/j.scitotenv.2024.172972

Abstract

Antimony (Sb) isotopes hold immense promise for unraveling Sb biogeochemical cycling in environmental systems. Mn oxides help control the fate of Sb via adsorption reactions, yet the behavior and mechanisms of Sb isotopic fractionation on Mn oxides are poorly understood. In this study, we examine the Sb isotopic fractionation induced by adsorption on β-MnO₂ in different experiments (kinetic, isothermal, effect of pH). We observe that adsorption on β-MnO₂ surfaces preferentially enriches lighter Sb isotopes through equilibrium fractionation, with Δ¹²³Sb_{aqueous-adsorbed} of 0.55-0.79 ‰. Neither the pH or surface coverage affects the fractionation magnitude. The analysis of extended X-ray absorption fine structure (EXAFS) demonstrates that the enrichment of light isotope results from the adsorption of inner-sphere complexation on solids. Our finding of this study enhances our comprehension of the impact of β-MnO₂ on Sb isotopic fractionation behavior and mechanism and facilitate the applicability of Sb isotopes as effective tracers to elucidate the origins and pathways of Sb contamination in environmental systems, as well as provide a new insight into forecasting the isotopic fractionation of other similar metals adsorbed by manganese oxides.

Keywords: Adsorption; Antimony; EXAFS; Isotopic fractionation; β-MnO(2).