Adsorption of U(VI) on the natural soil around a very low-level waste repository

Jingjing Wang; Shirong Qiang; Yun Wang; Wangsuo Wu; Ping Li; Haibo Qin; Qiaohui Fan

doi:10.1016/j.jenvrad.2021.106619

Adsorption of U(VI) on the natural soil around a very low-level waste repository

J Environ Radioact. 2021 Jul:233:106619. doi: 10.1016/j.jenvrad.2021.106619. Epub 2021 Apr 21.

Authors

Jingjing Wang¹, Shirong Qiang², Yun Wang³, Wangsuo Wu⁴, Ping Li⁵, Haibo Qin⁶, Qiaohui Fan⁷

Affiliations

¹ School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China. Electronic address: wangjj19@lzu.edu.cn.
² Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China.
³ Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
⁴ School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China. Electronic address: wuws@lzu.edu.cn.
⁵ Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China. Electronic address: liping@lzb.ac.cn.
⁶ State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China. Electronic address: qinhaibo@eps.s.u-tokyo.ac.jp.
⁷ Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Key Laboratory of Petroleum Resources, Gansu Province, Lanzhou, 730000, China. Electronic address: fanqh@lzb.ac.cn.

PMID: 33894498
DOI: 10.1016/j.jenvrad.2021.106619

Abstract

The behaviors of U(VI) in environmental media around radioactive waste disposal site are important for safety assessment of geological repositories. However, the estimation of environmental behaviors of U(VI) in natural media was insufficient. This work aimed to determine the adsorption of U(VI) on natural soil surrounding a candidate very low-level radioactive waste (VLLW) disposal site in southwest China. Results showed that the adsorption process of U(VI) on soils could be well supported by pseudo-second-order kinetic and Freundlich model. The adsorption of U(VI) was pH-dependent but temperature-independent. High ionic strength (NaCl) strongly affected the adsorption process at low pH (2.0-5.5). CO₃^2- remarkably inhibited the U(VI) adsorption, while the adsorption of U(VI) was promoted by PO₄^3- and SO₄^2-. Naturally occurred soil organic matters (SOMs) showed high affinity for U(VI), while the presence of additional humic acid (HA) strongly inhibited U(VI) adsorption. The occurrence of ferrous iron could result in the reduction of U(VI) at low pH values (pH < 4), leading to the promotion of immobilization of U(VI). These findings would provide some guidance for the safety assessments of the VLLW disposal as well as the remediation of contaminated soil.

Keywords: Adsorption; Fe(2+); Organic matters; Soil; Uranium.

MeSH terms

Adsorption
China
Hydrogen-Ion Concentration
Radiation Monitoring*
Soil
Uranium* / analysis

Substances

Soil
Uranium