Computational Study Of Boron Isotopic Separation Processes

High-purity boron isotopes are widely used in the fields of nuclear,medical,military and so on.So the development of boron isotopic production technology with independent intellectual property rights has important research significance and practical value.However,the lack of theoretical research in this process is becoming the bottleneck.In this paper,we use quantum chemistry and molecular simulation methods to research the mechanisms and separation factors(S)in three boron isotopic separation processes.They are chemical exchange distillation,ion-exchange chromatography and metal-organic frameworks(MOFs)adsorption,among which the third one is first proposed in this paper.In the chemical exchange distillation method,results from energy decomposition analysis and natural bond orbital analysis show that the value of separation factor is inversely proportional to the interaction force between B and O atoms.Then we used a large number of methods and basis sets to calculate the enthalpy change of the complexation reaction and the separation factor,in which M06-2X/6-31G(d,p)was the best one.It generate small errors for both quantities.Finally,SMD solvation model was innovatively introduced into the calculation of separation factor,making the relative errors of the separation factors in five complexing agent systems reduced to less than 10.8 %.The calculated results are in good agreement with the experimental results.In the ion-exchange chromatography method,we took Amberlite IRA-743 as example and calculated the separation factor of boron specific resin by quantum chemistry for the first time.The result from HF/6-31 G is found to be closest to the experimental value.Then S of various functional groups of chelating resins were calculated,among which phenols and carboxylic acids are found to have distinctly larger S than alcohols.This points out the direction for the development of new materials in chromatography.In the MOFs adsorption method,we analyzed the adsorption sites of boric acid in MIL-101(Cr)and cut off a small metal-cluster model to proceed quantum chemistry calculations of separation factors.S tended to 1.050(mono substitution reaction)and 1.076(bis substitution reaction)along with the change of basis sets.A theoretical model of boron adsorption on MIL-101(Cr)is preliminarily established here.