Studies On Thermodynamic Properties Of Rhenium Extraction In Ionic Lliquid System

Rhenium and its compounds are indispensable high-tech backing materials for many cutting-edge science and technology departments and are obviously armed with strong military colors.Rhenium has no independent deposits,often associated with non-ferrous metal ore body.The speciality of distribution increases the difficulty of its extraction and separation.Many chemists have concluded through extensive experimental research that the best method for extraction and separation of rhenium is solvent extraction.This type of extraction and separation technology are simple and easy to operate.It is usually performed at room temperature or lower temperature,and it is easy to realize in large-scale production.In the solvent extraction process of extracting rhenium,there is a disadvantage that the organic solvent used has certain harmful effects on the human body and the environment.Therefore,in this study,we used hydrophobic ionic liquid instead of the traditional organic solvent.Ionic liquids are environmentally friendly green solvents in the field of chemistry and chemical research because of their unique and excellent properties.In the extraction system,the hydrophobic ionic liquids chosen here are[C₅mim][PF₆]and[C₅mim][NTf₂],that are used as a diluent,and tri-n-octylamine?TOA?,three decyl alkyl tertiary amine?N235?were respectively used as extractants for extraction experiments.At the same extractant concentration and constant ion concentration,the extraction experiments were carried out at different temperatures?293.15 K to 318.15 K?and different ionic strengths?I=0.2 to 2.0?in a constant-temperature extraction device.The extraction data at different temperatures and different ionic strengths and the optimal conditions for extracting rhenium were obtained.In this study,the N235-[C₅mim][PF₆]system,TOA-[C₅mim][PF₆]system,N235-[C₅mim][NTf₂]system,and TOA-[C₅mim][NTf₂]system were further studied.The extraction equilibrium constants at different temperatures were calculated.Finally,other thermodynamic parameters were obtained by polynomial fitting,such as enthalpy,entropy change as well as gibbs free energy.It laid a solid foundation for the future industrial production of rhenium.