Parameterization Of Ionic Liquid UNIFAC-IL Model And Solvent Design Of Extraction Systems

In recent years,ionic liquids(ILs)have gained significant attention in numerous fields especially chemical separation processes for their unique physical and chemical propertie such as negligible volatility,high chemical/thermal stability,wide liquid range and designable character.Since it's difficult to screen a suitable ionic liquid for specific system with experiments alone,developing theoretical design and screening methods of ionic liquids is very important.The UNIFAC-IL model,which is a predictional model for thermodynamic properties of ionic liquids,plays a key role on ionic liquid design and screeing work.At first,the original UNIFAC-IL model is extended.Collecting infinite dilution activity coefficients data of alcohols,ethers,olefins and acetonitrile in 68 ILs at 298-428.15K from literature,four new substituent groups,namely,-C=C-,-O-,-OH and-CH2CN,are added to the original UNIFAC-IL model.Then 154 binary interaction parameters are fitted in total,which enrich the premier UNIFAC-IL model.The liquid-liquid equilibrium data of alcohol-ether-IL systems,alcohol-alkane-IL systems and olefin-alkane-IL systems are verified,which proves the credibility of the application of this developed UNIFAC-IL model.Secondly,a computer-aided ionic liquid design method based on the extended UNIFAC-IL model is established.A mixed-integer nonlinear programming(MINLP)problem which optimizes the extraction performance index(?×S)is formulated to program and select the proper ionic liquids with structural constraints,thermodynamic property constraints and physical property constraints.Finally,the proper ionic liquids of given separation systems are carried out with the support of this growing UNIFAC-IL model.The deep desulfurization system,n-hexane/methylcyclopentane system and n-hexane/1-nexene system are chosen as the design objects,and the results obtained by applying the developed UNIFAC-IL model confirm the truth of that more alternative and suitable entrainers can be picked out and.are with more high separation ability.