粘土对地下水中U（VI）的吸附作用及其污染控制研究

进行了U（VI）在粘土上吸附的批实验，其中，粘土样采自我国南方某大型铀尾矿库库底。实验结果表明U（VI）在粘土上的吸附与浸泡液的pH值呈强烈的非线性关系，在pH值近中性时，U（VI）在粘土上的吸附达到了一个最大值，而在偏酸性或偏碱性条件下，U（VI）在粘土上的吸附迅速减少；运用表面络合理论建立了U（VI）在粘土上吸附的表面络合模型（DLM），该模型很好地拟合了实验数据。模型检验表明，它可以精确预测U（VI）在不同热力学条件下的吸附行为；此外，模拟结果表明，U（VI）的粘土上吸附在酸性条件下受固液比（M／V）影响明显，而在碱性条件下主要受浸泡液中HCO3^-和CO3^2-的控制。

Study on Adsorption of Uranium(VI) on Clay and its Significance for Control of Ground Water Pollution

The batch experiments for adsorption of uranium(VI)on clay collected from the bottom of a huge mill-tailing in southern China were conducted.The results show that the adsorption of uranium(VI)on clay is a obviously nonlinear function of pH in solution,reaching a maximum around neutral pH and decreasing rapidly towards more acidic or alkaline conditions.The diffuse layer model (DLM) which describes the adsorption of uranium(VI) on clay was established according to the surface complexation approach,and it simulates the expermental data successfully.The calibration displays that the model has strong capacity to predict uranium(VI)sorption behavior under different thermodynamic condition.The simulating results indicate that U(VI) adsorption on clay is affected by solid-liquid ratio(M/V)obviously at low pH and controled by HCO-3+- and co-3+{2-} in solution at high pH.