铀酰离子吸附在高岭土基面的分子动力学模拟

Molecular Dynamics Modeling of Uranyl Ion Adsorption onto the Basal Surfaces of Kaolinite

为研究铀酰离子在高岭土不同基面上的吸附,对含有0.01mo·lL-1碳酸铀酰液相和9×9×3个高岭土单胞的粘土固相的模拟盒子进行了分子动力学模拟.从模拟的截图中直观地观察到了铀酰离子的吸附位点,由径向分布函数得到了铀酰离子与水中氧原子的配位情况.利用原子密度剖面图讨论铀酰离子在两个基面上的吸附倾向,并从原子密度剖面图和均方位移等角度证实了铀酰离子在硅氧面上形成了外界配合物.从理论上证明了表面配合模型对于吸附位点所做简化的合理性.

We performed a molecular dynamics simulation to investigate the adsorption of uranyl ions onto the basal surfaces of kaolinite using a simulation cell containing 0.01 mol？L-1 uranyl carbonate and 9×9×3 kaolinite unit cells.The adsorption sites of the uranyl ions on kaolinite were clearly shown by serial snapshots and the coordination of uranyl ions to oxygen were determined using a radial distribution function.The adsorption trends of uranyl ions on two distinct basal surfaces were discussed using an atomic density profile.Outer-sphere complexation of uranyl on kaolinite was confirmed using the atomic density profile and the mean squared displacement.Confirmation of the outer-sphere complexation supports the theoretical simplification of the adsoption sites in the surface complexation model.