Structure And Properties Of Actinide Organic Complexes

As long-time dependence on fossil energy such as coal,oil and natural gas,issues related to environment,economic and policy have been aroused public attention.Searching for new energy sources to replace fossil fuels has become an urgent and important problem in the world.In recent years,clean energy sources such as solar and wind power have been widely used.Among them,the nuclear energy produced by nuclear reactors may be one of the most perfect replacements for fossil fuel energy in many countries.However,there are still many scientific problems to be solved in the utilization of nuclear energy.How to safely dispose of spent fuel is one of the challenges.Actinides and fission products are the main components of spent fuel,which are highly radioactive and have a long half-life.If not well handled,it will have potentially harmful to the human living environment.Therefore,it is urgent to find new and efficient separating methods.The strong radioactivity and chemical toxicity of actinides bring great difficulties and risks for experimental researches.Designing ligands by computer has brought new insights to the separation of actinides.In this work,we mainly use density functional theory combined with chemical bond topological analysis methods to systematically analyze the geometric structure characteristics,the direction of electron transfer,the bonding characteristics and predicting the possible adsorption sites of fission product cations on actinide organic complexes.In section one,we used DFT and chemical bond topological analysis methods to explain the detailed information of molecular structures,electronic structure and bonding features between An O22+ and(COOCOO)2-.Our calculation results are in good agreement with the available experimental results of Wang group,which provides a comprehensive research support for the extraction of actinides from spent fuel with oxalic acid.The results show that the An-O bond is mainly an ionic interaction with a certain degree of covalent interaction,and the charge has a significant tendency to transfer from oxygen atoms to actinides.The adsorption sites of fission product cations appear between the adjacent oxalate molecules by analyzing the ESP on the [An O2(C2O4)3]4-complexes.In section two,we first proposed the contain and adsorption of actinides with siloxane.The calculations showed that An(IV)were mainly combined with siloxane by endohedral and exohedral methods.A series of theoretical analysis results show that there are mainly electrostatic interactions with a certain degree of covalent characteristics between An and O atoms.Covalent interaction is more obvious in An(IV)&(HSi O1.5)8,and An(IV)@(HSi O1.5)8 is more stable than An(IV)&(HSi O1.5)8.We found that the adsorption capacity of siloxane with different functional groups to An(IV)showed a trend of(HSi O1.5)8 <(Cl Si O1.5)8 <(OHSi O1.5)8.In addition,we have theoretically simulated IR and UV-Vis spectra,which can provide a reference to distinguish the two species in future experiments.Thus,this work not only describes a new method for encapsulating radioactive actinides,but also provides a new material for removing actinides.