Extension of the UNIFAC Model for Ionic Liquids

Abstract

The UNIFAC model has recently become very popular for ionic liquids (ILs) because of its applicability for prediction of thermodynamic properties. This work is a continuation of our studies on the extension of group parameters of the UNIFAC model to systems with ILs. The new IL groups for 33 main groups and 53 subgroups were added into the current UNIFAC parameter matrix. The parameters of group surface area and volume for ILs were obtained by the COSMO calculation, while the group binary interaction parameters, a nm and a mn , were obtained by means of correlating the activity coefficients of solutes at infinite dilution in ILs at different temperatures exhaustively collected from literature by the end of 2011. The predicted results of UNIFAC model are more accurate than those of the COSMO-RS model so that it can be used for identifying the general relationship between molecular structure of ILs and separation performance for the separation of liquid mixtures with ILs.

Separation of benzene and thiophene with a mixture of N -methyl-2-pyrrolidinone (NMP) and ionic liquid as the entrainer

“…In this work, the IL was decomposed into several functional groups in a similar way as proposed by Lei et al [31][32][33][34], Kim et al [35,36], Breure et al [37]. Meanwhile, the benzene molecule was decomposed as six ACH groups, whereas thiophene and NMP were each treated as one separate group.…”

Adsorptive absorption: A preliminary experimental and modeling study on CO2 solubility

“…where C ln i γ represents the combinatorial contribution containing two group parameters R k and Q k , which can be obtained from previous works; and R ln i γ represents the residual contribution, which is a function of the group interaction parameters α nm and α mn that can be found in previous reports (Gmehling, et al, 1982;Lei et al, 2009Lei et al, , 2012Lei et al, and 2014.…”

The Effect of C4H and C5H on the Microstructure of Aqueous Solutions of 1‐Alkyl‐3‐methylimidazolium Tetrafluoroborate Ionic Liquids

“…[33][34][35][36] There are two adjustable parameters in the Equation (7), namely (g 21 -g 11 ) and (g 12 -g 22 ), and other physicalq uantities can be obtained from the literature or calculations. Accordingt oE quations (1)-(6), the two interaction-energy parameters (g 21 4 -water mixtures are all shifted upfield upon dilution with water,w hereas those of OÀ Ha lways shift downfield, thus indicatingt hat the ILs dissociate gradually with increasing water contenta nd that the self-association interactions of water gradually replace the interactions between water andt he cations and anions,w hich is consistent with previousr eports.…”