【摘 要】
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The adsorption of UO2(H2O)52+ on the hydroxylated α-SiO2(001)surface was studied by a periodic density functional theory(DFT)and ab initio MD(AIMD)simulations.The effects of pH,CO2 and the aqua soluti
【机 构】
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CAS Key Laboratory of Nuclear Radiation and Nuclear Energy Techniques,and Multidisciplinary Initiati
论文部分内容阅读
The adsorption of UO2(H2O)52+ on the hydroxylated α-SiO2(001)surface was studied by a periodic density functional theory(DFT)and ab initio MD(AIMD)simulations.The effects of pH,CO2 and the aqua solution on the adsorption geometry and stability were also investigated.The results show that on the hydroxylated α-SiO2(001)surface,the adsodption of uranyl leads to the formation of inner-sphere complexes,in which the bidentate complex at the local deprotonated site is more favored.The binding strength of bidentate and monodentate complexes at the singly deprotonated site or at the protonated site are similar.The adsorption becomes weaker as the number of protons increases at the three kinds of sites,indicating that the adsorption strength increases with pH within a certain range.The adsorption process is not a simple ion-exchange or electrostatic adsorption process based on the fact that strong chemical interaction plays an important role in all inner-sphere complexes and the H-bonds are also formed between uranyl the hydroxylated surface.The outer-sphere complex by building only H bonds is much less stable.The presence of CO2 weakens the adsorption of uranyl on the surface due to its coordination to uranyl,and the explicit treatment of water environment has slight effect on the adsorption configuration.The results are consistent with the experimental observations.
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