Preparation of core-shell composite materials capable of slowly releasing phosphate and their remediation performance of uranium-contaminated groundwater

Liangbing Sheng; Hui Zhang; Jianhong Ma; Dexin Ding

doi:10.1016/j.chemosphere.2023.140160

Preparation of core-shell composite materials capable of slowly releasing phosphate and their remediation performance of uranium-contaminated groundwater

Chemosphere. 2023 Dec:344:140160. doi: 10.1016/j.chemosphere.2023.140160. Epub 2023 Sep 17.

Authors

Liangbing Sheng¹, Hui Zhang², Jianhong Ma², Dexin Ding³

Affiliations

¹ Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang 421001, China; Hunan Engineering Research Center for Monitoring and Treatment of Heavy Metal Pollution in the Upper Reaches of Xiangjiang River, Hengyang Normal University, Hengyang 421001, China; Hunan Province Key Laboratory of Green Development Technology for Extremely Low Grade Uranium Resources, Hengyang 421001, China.
² Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang 421001, China; Hunan Province Key Laboratory of Green Development Technology for Extremely Low Grade Uranium Resources, Hengyang 421001, China.
³ Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang 421001, China; Hunan Province Key Laboratory of Green Development Technology for Extremely Low Grade Uranium Resources, Hengyang 421001, China. Electronic address: zh2015yl@163.com.

PMID: 37716562
DOI: 10.1016/j.chemosphere.2023.140160

Abstract

Acid in-situ leach uranium mining significantly alters the geochemistry of the ore zone, and leaves uranium, residual acid, as well as other potential contaminants in groundwater, which bring harm to human health and ecological environment. Many investigators have been trying to propose remediation strategies for the uranium-contaminated groundwater. Phosphate is an effective immobilization reagent of uranium in the groundwater. However, direct injection of phosphate tends to quickly form precipitates, resulting in fast blockage of the seepage passages in the ore zone around the injection holes and hindering its diffusion. In this paper, HAP@SiO₂-600, HAP@SiO₂-600@25SA, and HAP@SiO₂-600@75SA with core-shell structures were prepared. Their slow-release of phosphate, the effects of pH, contact time, initial uranium concentration, and coexisting ions on their removal rate and efficiency of uranium, and their function of remediating uranium-contaminated groundwater were investigated. It was found that the increase of SA content in the outer layer of HAP@SiO₂-600@25SA and HAP@SiO₂-600@75SA resulted in the slow release rate of phosphate, decreasing the removal rate of uranium. The adsorption capacities of HAP@SiO₂-600, HAP@SiO₂-600@25SA, and HAP@SiO₂-600@75SA from the aqueous solution at pH = 3.0 and 303 K were up to 582.6, 558.5, and 507.3 mg g^-1, respectively. In addition, the materials showed excellent uranium removal performance in experiments where multiple ions coexisted. For actual acidic uranium-contaminated groundwater, HAP@SiO₂-600, HAP@SiO₂-600@25SA, and HAP@SiO₂-600@75SA effectively increased the pH from 2.75 to 4.40, 3.87, and 3.72, respectively, and decreased the uranium concentration from 5.12 to 0.0062, 0.0065, and 0.0058 mg L^-1, respectively. The FT-IR, XRD, TEM and XPS characterizations were performed to further clarify the uranium removal mechanism, and it was found that the elimination of U(VI) was ascribed to dissolution-precipitation, adsorption and ion exchange. The results show that the core-shell composite material capable of slowly releasing phosphate is effective in remediating uranium-contaminated groundwater.

Keywords: Acid in situ leach uranium mining; Slowly releasing phosphate; Uranium-contaminated groundwater.

MeSH terms

Adsorption
Groundwater* / chemistry
Humans
Phosphates / chemistry
Silicon Dioxide
Spectroscopy, Fourier Transform Infrared
Uranium* / analysis
Water Pollutants, Radioactive* / analysis

Substances

Uranium
Phosphates
Silicon Dioxide
Water Pollutants, Radioactive