Determination And Model Research Of Thermodynamic Properties Of Ionic Liquid Systems

Ionic liquids(ILs)are the innovation frontiers,which have the advantages of low melting points,low vapor pressure,less environment pollution,high chemical stability and thermal stability,etc.They have received great attention from many researchers,and their application fields of basic research and industry mainly focus on reactions and separations.The negligible vapor pressure makes ILs almost no loss in the distillation and separation process,the extremely wide temperature range of the liquid state makes them more widely used under normal pressure,and the strong designability enriches their variety,performance and application.The thermodynamic properties of ILs are the basis of their application research.Studying the thermodynamic properties of ILs can provide a theoretical basis for the engineering application of ILs and provide basic data for the construction of thermodynamic prediction models.Therefore,the determination and modeling of thermodynamic properties of ionic liquid(IL)systems have crucial theoretical significance and application value.The first part is determining the density and viscosity of binary systems containing ILs by Anton Paar density meter and viscometer,and fitting the apparent molar volume and viscosity by the Pitzer model and Erying kinetic equation,respectively,and exploring the mechanism of intermolecular interactions at the molecular level by the COSMO-RS model.In the second part,the vapor-liquid equilibrium experiments of methanol/acetonitrile-IL systems were determined by the static method,and the results were correlated by the UNIFAC and NRTL models,the corresponding group interaction parameters were supplemented,and good prediction results were obtained.In the third part,all the heat capacity data of ILs reported in the existing literature are collected,and the heat capacity database with a wide range of temperatures and heat capacities of many types of ILs is established,including 310 ILs and11873 data points.A group contribution method is proposed to predict the heat capacity of ILs at different temperatures,and a universal mathematical model for accurately predicting the IL heat capacity is obtained.The average absolute relative deviations of the heat capacity estimated by the two methods are 2.36% and 3.20%,respectively.The model researches of the density,viscosity,saturated vapor pressure and heat capacity of the IL systems supplemented the basic data of ILs,which provide references for the applications of ILs.