We like to highlight the extension of COSMO-based models (COSMO RS-FV and COSMO SAC-FV) to the prediction of gas solubility in polymers, including polymerized ionic liquids (PILs) for the first time. To verify the applicability of COSMO-based models, the predicted values for gas solubility in both common polymers (CH₄/N₂ + PEG) and PILs (CO₂ + P[MATMA][BF₄]/P[VATMA][BF₄]) were evaluated based on previous experimental data. It was confirmed that the COSMO-RS (Klamt) model performs better than the COSMO-SAC model for common polymers, whereas the COSMO-RS (ADF-Lei 2018) exhibits the best predictions for PILs. The moderately accurate predictions of COSMO-based models demonstrate the high potential for predicting gas solubility in polymers.

The CO₂ solubilities (including CO₂ Henry's constant) in physical- and chemical-based ILs/DESs and the COSMO-RS models describing these properties were comprehensively collected and summarized. The summarized results indicate that chemical-based ILs/DESs are superior to physical-based ILs/DESs for CO₂ capture, especially those ILs have functionalized cation and anion, and superbase DESs; some of the superbase DESs have higher CO ₂ solubilities than those of ILs; the best physical- and chemical-based ILs, as well as physical- and chemical-based DESs are [BMIM][BF₄] (4.20 mol kg⁻¹), [DETAH][Im] (11.91 mol kg⁻¹), [L-Arg]-Gly 1:6 (4.92 mol kg⁻¹) and TBD-EG 1:4 (12.90 mol kg⁻¹), respectively. Besides the original COSMO-RS mainly providing qualitative predictions, six corrected COSMO-RS models have been proposed to improve the prediction performance based on the experimental data, but only one model is with universal parameters. The newly determined experimental results were further used to verify the perditions of original and corrected COSMO-RS models. The comparison indicates that the original COSMO-RS qualitatively predicts CO₂ solubility for some but not all ILs/DESs, while the quantitative prediction is incapable at all. The original COSMO-RS is capable to predict CO₂ Henry's constant qualitatively for both physical-based ILs and DESs, and quantitative prediction is only available for DESs. For the corrected COSMO-RS models, only the model with universal parameters provides quantitative predictions for CO₂ solubility in physical-based DESs, while other corrected models always show large deviations (> 83%) compared with the experimental CO₂ Henry's constants.

The chlorine (Cl₂) drying technology using ionic liquids (ILs) as absorbents was proposed for the first time and systematically investigated from the molecular level scaled up to the industrial level. The hygroscopic IL [EMIM][CH₃SO₃] was screened as a suitable absorbent from 238 potential IL candidates consisting of 14 cations and 17 anions, by calculating the Cl₂ and H₂O solubility and separation selectivity of Cl₂ to H₂O in different ILs based on the COSMO-RS model. The microscopic atomic and molecular insights into the separation mechanisms were deeply revealed by using COSMO-RS model analyses (i.e., σ-profiles, σ-potentials, excess enthalpies, entropies, and Gibbs free energies) and quantum chemistry calculation (binding energies and weak interaction analyses). The Cl₂ solubility in pure IL and H₂O + IL systems were predicted by the COSMO-RS model, and the results agree with the microscopic mechanism identification. Moreover, the strict equilibrium stage model employed with the COSMO-RS model parameters was built to perform the process simulation, and continuous Cl₂ drying with ILs was conceptually designed and optimized at industrial scale. It was confirmed that [EMIM][CH₃SO₃] is a very promising absorbent leading to a less IL amount, a much lower energy consumption than the other IL [EMIM][BF₄], which has a very bright industrialization potential used for Cl₂ drying technology.

The ionic liquid (IL) 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][DCA]) was selected as an appropriate entrainer for the extractive distillation of the methanol–ethanol-water mixture. The COSMO-RS model was applied to screen out the appropriate solvents considering selectivity and solvent capacity together. Isobaric vapor–liquid equilibrium (VLE) experiments for the two systems of methanol–water and ethanol–water with different amounts of [EMIM][DCA] added were conducted at 101.3 kPa. The experimental data showed that [EMIM][DCA] exhibits an obvious salting effect for the methanol (or ethanol)-water mixture and eliminates the azeotropic point of ethanol–water. Moreover, the predicted values by UNIFAC-Lei model coincide well with experimental data. The separation mechanism was further explained in combination with surface charge density distribution (σ-profiles), excess enthalpy (H), and binding energy. In addition, the flow charts were designed to evaluate the improvement of energy consumption with [EMIM][DCA] as the entrainer when compared to ethylene glycol (EG). The simulation results demonstrated that [EMIM][DCA] is more energy efficient than EG.

For the design of eutectic solvents (ESs, usually also known as deep eutectic solvents), the prediction of the solid–liquid equilibria (SLE) between candidate components is of primary relevance. In the present work, the SLE prediction of binary eutectic solvent systems by the COSMO-RS model is systematically evaluated, thereby examining the applicability of this method for ES design. Experimental SLE of such systems are first collected exhaustively from the literature, following which COSMO-RS SLE calculations are accordingly carried out. By comparing the experimental and predicted eutectic points (eutectic temperature and eutectic composition) of the involved systems, the effects of salt component conformer and COSMO-RS parameterization as well as the applicability for different types of components (specifically the second component paired with the first salt one) are identified. The distinct performances of COSMO-RS SLE prediction for systems involving different types of components are further interpreted from the non-ideality and fusion enthalpy point of view.

The selection of phase change material (PCM) plays an important role in developing high-efficient thermal energy storage (TES) processes. Ionic liquids (ILs) or organic salts are thermally stable, non-volatile, and non-flammable. Importantly, researchers have proved that some ILs possess higher latent heat of fusion than conventional PCMs. Despite these attractive characteristics, yet surprisingly, little research has been performed to the systematic selection or structural design of ILs for TES. Besides, most of the existing work is only focused on the latent heat when selecting PCMs. However, one should note that other properties such as heat capacity and thermal conductivity could affect the TES performance as well. In this work, we propose a computer-aided molecular design (CAMD) based method to systematically design IL PCMs for a practical TES process. The effects of different IL properties are simultaneously captured in the IL property models and TES process models. Optimal ILs holding a best compromise of all the properties are identified through the solution of a formulated CAMD problem where the TES performance of the process is maximized. [MPyEtOH][TfO] is found to be the best material and excitingly, the identified top nine ILs all show a higher TES performance than the traditional PCM paraffin wax at 10 h thermal charging time.

2-Ethylhexyl acrylate (2-EHA) is one of the most widely used acrylates in the polymer industry, which is synthesized via Fisher esterification that is limited by chemical equilibrium. To intensify the esterification process, in this work, reactive extraction concept is proposed, with halogen-free deep eutectic solvent (DES [Im:2PTSA]) as dual solvent-catalyst that consists of imidazole (Im) andp-toluenesulfonamide (PTSA). The bifunctional effects of the DES [Im:2PTSA] are evaluated by thermodynamic analysis and experimental study. Favorable phase splitting is verified byσ-potential analysis predicted by COSMO-RS theory, combined with experiments, and the optimal acid-to-alcohol molar ratio is set to 1.2. The esterification kinetics is then experimentally determined and fitted using the molar-based and activity-based pseudo-homogeneous (PH) models, respectively. The activity-based PH model, that considers the bifunctional roles of the DES, proves to be more accurate with small RMSD of 0.0344. The stability of DES after recycling is validated to further confirm the industrial prospects of DES [Im:2PTSA] in 2-EHA production.

A suitable ionic liquid for methyl chloride drying experiment was screened out from 210 ionic liquids by COSMO-RS model. Moreover, the experimental mechanism of ionic liquids drying is further explained by the COSMO-RS model, and it is further confirmed by analyzing the binding energy. The solubility of methyl chloride in [EMIM][BF₄] and TEG and [EMIM][BF₄]+H₂O was completed, and the experimental results well proved the reliability of the UNIFAC-Lei model. The unknown interaction parameters were obtained through the solubility data of this work and the experimental data in the literatures. The methyl chloride drying experiment was completed in the laboratory, and the water content of the methyl chloride can be reduced to below 200 ppm. The simulation of the methyl chloride drying process using [EMIM][BF ₄] or TEG as absorbents was carried out by ASPEN software on an industrial scale. The final simulation results show that the [EMIM][BF₄] drying process has lower energy consumption and better drying effect.

1,5-Pentanediamine (PDA) produced by biological fermentation becomes popular, but the separation of PDA from the broth is a typical difficult problem. In this work, the performance of 200 ionic liquids (ILs), formed by combining 25 cations and 8 anions, in the extraction of PDA from aqueous solution were evaluated using COSMO-RS model. The extraction mechanism was investigated with the help of σ-profile and interaction energy analyses. Both the cation and anion have impacts on the extraction efficiency, where cation mainly influences the interaction of IL with PDA and anion affects the hydrophobicity of IL. The IL composed of long alkyl-chain in cation and the anion of [PF₆]^- or [TF₂N]^-, which has the σ-profile more likely distributed in the nonpolar region but less distributed in the polar region, is favorable for extraction. The experimental liquid–liquid equilibrium demonstrated the effects of cation and anion on extraction performance, which validated the reliability of COSMO-RS model in IL screening for PDA extraction. The IL [IM-1,8][PF₆] could serve as a promising extractant for the downstream separation process of the biological production of PDA.

Rational design of ionic liquids (ILs), which is highly dependent on the accuracy of the model used, has always been crucial for CO₂ separation from flue gas. In this study, a support vector machine (SVM) model which is a machine learning approach is established, so as to improve the prediction accuracy and range of IL melting points. Based on IL melting points data with 600 training data and 168 testing data, the estimated average absolute relative deviations (AARD) and squared correlation coefficients (R²) are 3.11%, 0.8820 and 5.12%, 0.8542 for the training set and testing set of the SVM model, respectively. Then, through the melting points model and other rational design processes including conductor-like screening model for real solvents (COSMO-RS) calculation and physical property constraints, cyano-based ILs are obtained, in which tetracyanoborate [TCB]^- is often ruled out due to incorrect estimation of melting points model in the literature. Subsequently, by means of process simulation using Aspen Plus, optimal IL are compared with excellent IL reported in the literature. Finally, 1-ethyl-3-methylimidazolium tricyanomethanide [EMIM][TCM] is selected as a most suitable solvent for CO₂ separation from flue gas, the process of which leads to 12.9% savings on total annualized cost compared to that of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [EMIM][Tf₂N].

The benzene and acetonitrile azeotropic mixture was proposed to be separated by extractive distillation using an ionic liquid (IL) as the entrainer. The suitable IL was selected by the COSMO-RS model, and 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF₄]) was considered as the suitable entrainer mainly due to its high selectivity, low viscosity, and low price. The experimental vapor pressure data of the IL-containing systems (benzene + [EMIM][BF₄] and acetonitrile + [EMIM][BF₄]) were measured in the full concentration range. The results show that acetonitrile has a stronger interaction with IL than benzene, and the low deviations between the experimental and UNIFAC predicted values show the reliability of the UNFIAC model. The UNIFAC predicted vapor–liquid equilibrium data of the benzene + acetonitrile + dimethyl sulfoxide (DMSO)/[EMIM][BF₄] system show that the relative volatility of benzene to acetonitrile is higher when the entrainer is [EMIM][BF₄]. The process simulation results show that [EMIM][BF₄] can reduce the material and energy consumptions compared with DMSO.