不同因素对砂岩含水层介质吸附铀的影响 Factors affecting uranium adsorption on aquifer sandstone期刊界 All Journals 搜尽天下杂志传播学术成果专业期刊搜索期刊信息化学术搜索

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不同因素对砂岩含水层介质吸附铀的影响

引用本文：	惠淑君,杨冰,郭华明,连国玺,孙娟.不同因素对砂岩含水层介质吸附铀的影响[J].地学前缘,2021,28(5):68-78.

作者姓名：	惠淑君杨冰郭华明连国玺孙娟

作者单位：	中国地质大学(北京)水资源与环境学院,北京100083;中国地质大学(北京)水资源与环境学院,北京100083;中核第四研究设计工程有限公司,河北石家庄050021;中核第四研究设计工程有限公司,河北石家庄050021

基金项目：	中核集团集中研发项目(中核科发(2018)111号);国家自然科学基金项目(41825017)

摘要：	铀矿开采过程中及井场退役后,含铀浸出液的扩散会对地下水造成一定影响,该影响范围和程度决定了铀的天然衰减特征。本文以北方某地浸铀矿区砂岩含水介质为研究对象,研究了溶液化学特征和黄铁矿含量对砂岩吸附和转化铀的影响。结果表明,砂岩颗粒对U(VI)的吸附基本在12 h可达平衡。线性等温吸附模型可以很好地描述吸附特征;砂岩颗粒对U(VI)的吸附率总体随着粒径增大而减小,当岩石粒径增大到0.200.25 mm时,吸附率趋于稳定。溶液pH值是影响吸附的主要因素,通过控制溶液中U(VI)的络合形态和岩石颗粒表面带电荷情况,在库仑力的作用下促进或者抑制吸附,在pH=6时,达到最佳吸附状态。共存离子对U(VI)吸附的抑制程度是: $HCO 3 -$ >Ca²⁺>Mg²⁺> $SO 4 2 -$ 。 $HCO 3 -$ 主要通过与 $UO 2 2 +$ 络合形成带负电荷的络合阴离子抑制U(VI)吸附。近中性pH值试验条件下,黄铁矿含量的增加对U的去除起到显著的促进作用,这种促进作用体现在吸附和还原作用,被吸附的Fe²⁺在吸附剂表面通过电子转移还原吸附态的U(VI),还原产物是UO₂₊_x,吸附和还原是个相互促进的过程;在弱碱性pH值试验条件下,黄铁矿对U(VI)去除的影响不明显,水解沉淀作用和较低的吸附率抑制了还原反应的发生。
关键词：	铀砂岩黄铁矿吸附还原
收稿时间：	2020-08-17
Factors affecting uranium adsorption on aquifer sandstone

HUI Shujun,YANG Bing,GUO Huaming,LIAN Guoxi,SUN Juan.Factors affecting uranium adsorption on aquifer sandstone[J].Earth Science Frontiers,2021,28(5):68-78.

Authors:	HUI Shujun YANG Bing GUO Huaming LIAN Guoxi SUN Juan

Institution:	1. School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, China2. The Fourth Research and Design Engineering Corporation of CNNC, Shijiazhuang 050021, China

Abstract:	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. $HCO 3 -$ shows the most negative effect on U(VI) adsorption, followed by Ca²⁺, Mg²⁺, and $SO 4 2 -$ . $HCO 3 -$ inhibits U(VI) adsorption mainly by forming negatively charged $UO 2 2 +$ 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.

Keywords:	uranium sandstone pyrite adsorption reduction
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