地浸井场外围含水层砂岩对铀的吸附行为

天然含水层介质对铀的吸附是地下水铀天然衰减的决定因素.然而，人们对天然含水层砂岩吸附铀行为的认识相当有限.因此，本文采用静态实验及数值模拟相结合的方法研究了地浸井场外围砂岩对铀的吸附行为，探究了天然砂岩对溶液中铀的吸附动力学和等温吸附特征，研究了铀初始浓度、pH、其他离子种类与浓度对铀吸附的影响.结果表明，准二级动力学方程与Freundlich等温吸附模型可以更好地表征砂岩对铀的吸附行为；随着溶液中铀初始浓度的增大，砂岩对水溶液中铀的吸附量增大，吸附率减小；在初始pH=3时，铀的吸附率达到最大，为77%；砂岩对溶液中铀的吸附率会随反应体系中Ca²⁺、Mg²⁺、SO₄^2-、HCO₃^-等离子浓度的升高而下降，4种共存离子对该吸附过程抑制能力的顺序为：SO₄^2- < Mg²⁺ < Ca²⁺ < HCO₃^-.这些研究结果可为地浸铀矿山地下水的修复提供理论支持.

Adsorption of uranium on aquifer sandstone obtained near in-situ leaching uranium mine

Uranium (U) adsorption on natural aquifer media is a vital process determining natural attenuation of groundwater U. However, less is known about U adsorption on aquifer sandstone. Adsorption of uranium on aquifer sandstone obtained near the in-situ leaching uranium mine was studied by using batch experiments and numerical simulation to characterize adsorption kinetics, isothermal adsorption, and effects of initial concentrations of U(VI), pH, major ions on U adsorption on the sandstone. The results showed that the quasi-second-order kinetic equation and Freundlich isothermal adsorption model well delineated the adsorption process of U on the sandstone. With the increase in initial U concentration, the amount of adsorbed U on the sandstone increased, but adsorption efficiency decreased. At initial pH around 3, the adsorption efficiency was the highest, which was up to 77%. Uranium adsorption on the sandstone decreased with the increase in concentrations of Ca²⁺, Mg²⁺, SO₄^2-, and HCO₃^-. The order of the adsorption inhibition by coexisting major ions was shown as follows: SO₄^2- < Mg²⁺ < Ca²⁺ < HCO₃^-. This study provides the theoretical supports for in-situ remediation of U-contaminated groundwater.