Preliminary Application Of The Molecular Interaction Volume Model In Ionic Liquids

In recent years,ionic liquids have been widely used in extractive distillation separation of organic and aqueous solutions because of their special physical properties.Thermodynamic application of ionic liquids provides valuable basic reference data for selecting suitable separation agents for the difficult problems of azeotrope separation.At present,can be applied to the calculation of ionic liquid thermodynamic activity thermodynamic models NRTL,Wilson,UNIQUAC,UNIFAC and other models.Among them,NRTL has a better effect in ionic liquids,and the effect of mixing enthalpy is mainly considered in NRTL.The molecular interaction volume model(MIVM)is a local composition model,which takes into account the enthalpy and entropy effects in solution systems.In the past 20 years,this model has been widely used in liquid alloy and slag,and can also be used in organic and polymer solutions.This shows that the model has a promising application in ionic liquids.This paper presents a method to determine the model parameters by using only the infinite sparse activity coefficient of a single component.In order to verify the reliability and accuracy of this method,first of all,choose the liquid alloy within the range of concentration of verification,the results show that the two MIVM and NRTL model of binary liquid system of Sn-zinc alloy,Bi-Pb and Ag-Au calculation value and experimental value of the average relative error was 4.6%,9.3%,1.4%,10.2%,6.6%,8.7%,this indicates that the method is reliable.The average relative errors of MIVM and NRTL were 9.5%and 23.4%,respectively,in the ionic liquid systems of water-[BMIM][DCA]and water-[EMIM][SCN].The reliability of the method was verified again,and the total concentration activity was predicted on this basis.Based on the molecular interaction volume model(MIVM),five kinds of anions were used as the research objects.The thermodynamic activities of each group of ionic liquid-water,ionic liquid-organic matter and water-organic matter involved in ionic liquid were calculated.In the anion[NTf₂],compared with the literature experimental values,the mean relative errors of MIVM of[N₁₁₁₂OH][NTf₂]?[DoMIM][NTf₂]and[P_8,8,8,8][NTf₂]were 0.4%,0.5%and 0.7%,and the mean relative errors of NRTL were 0.8%,1.5%and 1.8%.In the anion[TCM],compared with the experimental values,the mean relative errors of MIVM of[BMMOR][TCM]?[EMIM][TCM]and[BMPYR][TCM]were 1.1%,0.4%and 0.9%,and the mean relative errors of NRTL were 1.7%,0.8%and 1.4%,respectively.In the anion[DCA],compared with the experimental values,the mean relative errors of MIVM of[(C₃COOMe)MIM][DCA]?[N-C₃OHMIM][DCA]?[N-C₃OHMMor][DCA]were0.5%,0.9%and 1.0%,and the mean relative errors of NRTL were 0.6%,0.9%and1.1%.In the anion[Tf₂N],compared with the experimental values,the mean relative errors of MIVM of[MeOCH₂CH2NEt₃][Tf₂N]?[MeOCH₂CH2PEt₃][Tf₂N]and[MeOCH₂CH2PBu₃][Tf₂N]were 1.7%,1.3%and 0.9%,and the mean relative errors of NRTL were 1.0%,2.2%and 2.1%.In the anion[FSI],the mean relative errors of MIVM of[Pr MPyr][FSI]?[BMPyr][FSI]and[MPr Pip][FSI]were 1.9%,2.6%and2.4%,and the mean relative errors of NRTL were 2.7%,3.5%and 3.6%,compared with the experimental values.In general,the total mean relative errors of MIVM and NRTL for[NTf₂]?[TCM]?[DCA]?[Tf₂N]and[FSI]were 1.2%and 1.7%,respectively,and MIVM was superior to NRTL in the calculation of the activity coefficient of ionic liquids.Based on the good fitting ability of MIVM in systems with large molecular volume difference,MIVM was applied to the activity prediction of ternary systems in ionic liquid extractive distillation.In this paper,the total concentration activity of each component has been predicted for the ternary system of ionic liquid-water-butanol and ionic liquid-benzene-cyclohexane.The above research results will provide valuable thermodynamic data and calculation model for the production process of ionic liquid...