Factors affecting uranium adsorption on aquifer sandstone

被引：0
|
作者：
Hui S. [1 ]
Yang B. [1 ,2 ]
Guo H. [1 ]
Lian G. [2 ]
Sun J. [2 ]
机构：
[1] School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing
[2] The Fourth Research and Design Engineering Corporation of CNNC, Shijiazhuang
来源：
Earth Science Frontiers | 2021年 / 28卷 / 05期
关键词：
Adsorption; Pyrite; Reduction; Sandstone; Uranium;
D O I：
10.13745/j.esf.sf.2021.2.19
中图分类号：
学科分类号：
摘要：
During and after in situ uranium (U) mining, the diffusion of U-containing leachate can potentially have an impact on the groundwater quality. The range and magnitude of such impact determines the natural attenuation of U(VI) in groundwater in sandstone aquifers. This study investigates the influence of solution chemistry characteristics and pyrite content in sandstone on the U(VI) adsorption/transformation by aquifer sandstone taken from a uranium mining area in northern China. Adsorption equilibrium in sandstone particles can be reached after 12 h. The linear adsorption isotherm fits will with the observed data. The adsorption efficiency generally decreases with increasing grain size but stabilizes under grain size larger than 0.20-0.25 mm. The solution pH is the main factor affecting adsorption. By controlling the U(IV) complexes in solution as well as rock particle surface charge, adsorption is promoted at pH < 6 and inhibited at pH > 6. HCO3- shows the most negative effect on U(VI) adsorption, followed by Ca2+, Mg2+, and SO42-. HCO3- inhibits U(VI) adsorption mainly by forming negatively charged UO22+ complexes. At near neutral pH, the increase of pyrite content significantly promotes U(VI) removal by adsorption and reduction, as the adsorbed Fe2+ reduces U(VI) to UO2+x by electron transfer on the surface of the adsorbent. Adsorption and reduction are mutually reinforcing processes. Under weakly alkaline condition, increasing pyrite content does not significantly affect U(VI) removal, as hydrolytic precipitation and low adsorption inhibit the reduction of U(VI) by pyrite. © 2021, Editorial Office of Earth Science Frontiers. All right reserved.
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页码：68 / 78
页数：10
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