摘要
We use molecular dynamics simulation to study the mechanisms involved in the adsorption of aqueous uranyl species(UO_2^(2+)) to the basal surfaces of clay minerals,including kaolinite,pyrophyllite and montmorillonite.Uranyl ion can form various complexes with carbonates,namely,[UO_2(H_2O)_5]^(2+),[UO_2(H_2O)3(CO_3)],[UO_2(H_2O)2(CO_3)_2]^(2-),[UO_2(CO_3)_3]^(4-).The simulations show that at aqueous clay interfaces,both uranyl species and surface type control the adsorption pattern.The noncarbonato and monocarbonato uranyl species can form outer-sphere complexes on siloxane surfaces through electrostatic interaction,but the dicarbonato and tricarbonato uranyl complexes rarely adsorb on the siloxane surfaces.Strong outer-sphere adsorptions of the uranylcarbonate complexes on gibbsite surfaces are observed,which are fixed by hydrogen bonds between the ligands(carbonate and/or H_2O) and surface hydroxyls.The sorption behaviors derived in this study provide new insights into understanding the migration and enrichment of uranium and other radionuclides.
We use molecular dynamics simulation to study the mechanisms involved in the adsorption of aqueous uranyl species（UO2^2＋） to the basal surfaces of clay minerals,including kaolinite,pyrophyllite and montmorillonite.Uranyl ion can form various complexes with carbonates,namely,[UO2（H2O）5]^2＋,[UO2（H2O）3（CO3）],[UO2（H2O）2（CO3）2]^2-,[UO2（CO3）3]^4-.The simulations show that at aqueous clay interfaces,both uranyl species and surface type control the adsorption pattern.The noncarbonato and monocarbonato uranyl species can form outer-sphere complexes on siloxane surfaces through electrostatic interaction,but the dicarbonato and tricarbonato uranyl complexes rarely adsorb on the siloxane surfaces.Strong outer-sphere adsorptions of the uranylcarbonate complexes on gibbsite surfaces are observed,which are fixed by hydrogen bonds between the ligands（carbonate and/or H2O） and surface hydroxyls.The sorption behaviors derived in this study provide new insights into understanding the migration and enrichment of uranium and other radionuclides.
基金
National Science Foundation of China(Nos.41002013,40973029,41273074 and 41222015)
the Foundation for the Author of National Excellent Doctoral Dissertation of PR China(No.201228)
Newton International Fellowship Program
the financial support from the State Key Laboratory for Mineral Deposits Research
