Ionic Liquid Systems Research Articles

Prediction surface tension of ionic liquid–water mixtures using a hybrid group contribution and artificial neural network method

In this work, a database was established to collect relevant surface tension data (4578 sets of data points in total) for 138 ionic liquids (ILs)-H2O hybrid systems. An ANN-GC model for predicting the surface tension of IL-H2O hybrid systems is proposed to be constructed by combining the group contribution (GC) method and artificial neural network (ANN) algorithm. This model correlates surface tension to temperature together with IL structure and is developed by using machine learning algorithms. The results show that the model with 4, 5 and 7 neurons in the hidden layer is able to provide reliable predictions for the surface tension of the IL-H2O hybrid system. When 4, 5 and 7 neurons are used in the hidden layer of the model, the squared correlation coefficients (R2) of the training set are 0.92, 0.93 and 0.93; the MAE are 0.0021, 0.0020 and 0.0020, respectively. While the squared correlation coefficients (R2) of the test set are 0.94, 0.91,0.91 and the MAE are 0.0023, 0.0029, 0.0027, respectively. Meanwhile, the ANN-GC model of the hybrid system was extended and an ANN-GC model of pure ILs was constructed based on 172 surface tension data of pure ionic liquids. The comparison shows that the model with 4 and 5 neurons in the hidden layer can be extended to the pure IL system to provide reliable prediction of the surface tension for the pure IL system.

Extraction separation of lithium isotopes with Bromobenzene-15-crown-5/ionic liquids system: Experimental and theoretical study

Controlled fusion energy is considered to be one kind of sustainable energy source with clean and green properties. The fusion process requires a large number of lithium isotopes, but the naturally stable lithium isotopes 6Li and 7Li cannot be directly applied to the fusion process and must be further enriched. In this paper, a system for the separation of lithium isotopes by extraction was investigated, which mainly consists of bromobenzene-15-crown-5 and ionic liquids. The effects of ionic liquids, lithium salts, crown ether concentration, and temperature on the separation performance of lithium isotopes were explored. It was found that 6Li was enriched in the organic phase and the single-stage separation factor reached 1.032. It was proved by the temperature experiment that the exchange of lithium isotopes was a spontaneous and exothermic process. The complexation ratio of crown ether and lithium ions was 1:1. The optimized complexation model and the interaction of crown ether and lithium ions were calculated by DFT and Multiwfn. Lithium ions were weakly bonded to the crown ether and strongly bonded to the water molecule as demonstrated by the non-bonded interactions and Mayer bond order of Li-O. Meanwhile, the mechanism of lithium isotope separation with crown ether was clarified by mutual verification of experiment and theoretical calculations.

A novel method for prediction of refractive index of ionic liquids and alcohol binary systems

Recently, ionic liquids as a new group of solvent have successfully showed high capacity for applications in chemical engineering industries because of their desirable properties so knowledge of their properties such refractive indices of the binary system of alcohols and ionic liquids have high importance. This paper presents predictive tool based Least Squares Support Vector Machine optimized by Particle swarm optimization to determined refractive index of this binary system. In order to prepare the mentioned algorithm, a comprehensive databank contains 688 experimental refractive indices of the binary system of different alcohols and ionic liquids is used. The developed method shows satisfying results based on statistical and graphical comparisons. Furthermore the effects of different inputs on refractive index term has been investigated by a novel sensitivity analysis.

Multifunctional porous β-cyclodextrin polymer for water purification

Keeping water clean is of vital significance for human health and environmental protection. In order to remove organic micro-pollutants and natural organic substances in water bodies and kill pathogenic microorganisms simultaneously, this study synthesized a multifunctional porous β-cyclodextrin polymer with a high specific surface area by introducing quaternary ammonium groups and rigid benzene rings, respectively, which was then polymerized with crosslinking agent-4,4′-bis (chloromethyl)-1,1′-biphenyl (BCMBP) in an ionic liquid system. The grafting of quaternary ammonium groups was beneficial for the removal of negative-charged humic acid (HA) and sterilization. The introduction of numerous rigid structures during benzylation and Friedel-Crafts alkylation reaction could significantly improve the porosity and specific surface area of the polymer, conducive to the exposure of cyclodextrin binding sites and contaminant adsorption. By changing the proportions of quaternization and benzylation, the structure and surface properties of the polymer could be adjusted, thus further regulating the adsorption performance. Compared with activated carbon, the polymer named BQCD-BP with a huge surface area of 1133 m2 g−1 prepared under optimized conditions showed outstanding adsorption performance and sterilization ability. The pseudo-second-order kinetic constant of BQCD-BP reached 1.2058 g·mg−1·min−1, which was approximately 50 times greater than that of activated carbon (0.0256 g·mg−1·min−1) under the same experimental condition. The adsorption capacity of BQCD-BP to HA was twice as high as that to AC, and the antibacterial ability of BQCD-BP was significant, achieving 90% at the dosage of 1g L−1. Moreover, the adsorption process was hardly affected by the hydrochemical conditions, and the polymer was easy to regenerate. In addition, the excellent adsorption and antibacterial performance of the polymer were also identified by natural water treatment. COD was almost completely removed, and the removal efficiency of TP reached 92% after contact with BQCD-BP. The sterilization rate of BQCD-BP to viable bacteria in complex water bodies reached 82%. Undoubtedly, BQCD-BP is a potential multifunctional water treatment material with reasonable design in the actual water purification.

Water in ionic liquids: Raman spectroscopic studies

AbstractThe application of Raman spectroscopy in studies of ionic liquid (IL) systems having water is presented here. The presence of water can be intentional or unintentional. Since water severely affects IL's physical and chemical properties, it is very important not only to identify but also to understand the role of water. It will be evident from this short review that Raman spectroscopy has immensely helped to understand the IL/water mixture at the molecular level.

Physical interpretation of theories of homogeneous electrolytes in the primitive model

The primitive model of ions is an important model system of electrolytes and ionic liquids because it is the simplest one to include both electrostatic and ion size effects. Here, two recent theories of the electrostatic excess chemical potential of homogeneous electrolytes modeled in the primitive model are analyzed. Both the Mean Countershell Approximation (MCSA) and the Extended Mean Spherical Approximation (MSAX) theories were already known to be accurate when compared to Grand Canonical Monte Carlo simulation results. The analysis here uncovers why these two seemingly very different theories agree very closely numerically. Moreover, knowledge of the physical meaning of the MCSA theory is used to define the MSAX theory’s terms as electrostatic interactions of ionic screening clouds. Lastly, a mathematical analysis of MCSA, MSAX, and a third theory is performed. This shows how all these theories—despite using very different mathematical and physical approximations—couple the distinct physical regimes of the low- and high-density limits to get accurate results at intermediate ion densities.

Enrichment in CO2 Absorption by 2-Methyl Piperazine-Activated Tertiary Amines, Physical Solvents, and Ionic Liquid Systems.

One of the ever-demanding research fields is the development of new solvents with better properties for mitigation of CO2 compared to existing solvents. This work reports the measurement and modeling of CO2 solubility in newly proposed aqueous solvent blends of 2-methyl piperazine with N-methyldiethanolamine (MDEA), sulfolane (TMSO2), and 1-butyl-3-methyl-imidazolium acetate ([bmim] [Ac]). The operating temperature and CO2 partial pressure conditions chosen were 303.2–323.2 K and 2–370 kPa, respectively. Along with this, qualitative 13C NMR and FTIR analysis were also performed to consider the proposed reaction scheme. The experimental vapor–liquid equilibrium data were modeled by a modified Kent–Eisenberg equilibrium model. The equilibrium constants associated with 2-methyl piperazine (2-MPZ) and [bmim] [Ac] deprotonation and carbamate formation reactions were regressed to fit the experimental CO2 solubility data. In addition, the CO2 cyclic capacity and heat of absorption were evaluated for the aq (MDEA + 2-MPZ) blend.

Nonpolarizable Force Fields through the Self-Consistent Modeling Scheme with MD and DFT Methods: From Ionic Liquids to Self-Assembled Ionic Liquid Crystals.

A key to achieve the accuracy of molecular dynamics (MD) simulation is the set of force fields used to express the atomistic interactions. In particular, the electrostatic interaction remains the main issue for the precise simulation of various ionic soft materials from ionic liquids to their supramolecular compounds. In this study, we test the nonpolarizable force fields of ionic liquids (ILs) and self-assembled ionic liquid crystals (ILCs) for which the intermolecular charge transfer and intramolecular polarization are significant. The self-consistent modeling scheme is adopted to refine the atomic charges of ionic species in a condensed state through the use of density functional theory (DFT) under the periodic boundary condition. The atomic charges of the generalized amber force field (GAFF) are effectively updated to express the electrostatic properties of ionic molecules obtained by the DFT calculation in condensed phase, which improves the prediction accuracy of ionic conductivity with the obtained force field (GAFF-DFT). The derived DFT charges then suggest that the substitution of a hydrophobic liquid-crystalline moiety into IL-based cations enhances the charge localization of ionic groups in the amphiphilic molecules, leading to the amplification of the electrostatic interactions among the hydrophilic/ionic groups in the presence of hydrophobic moieties. In addition, we focus on an ion-conductive pathway hidden in the self-assembled nanostructure. The MD results indicate that the ionic groups of cation and anion interact strongly for keeping the bicontinuous nanosegregation of ionic nanochannel. The partial fractions of hydrophilic/ionic and hydrophobic nanodomains are then quantified with the volume difference from referenced IL systems, while the calculated ionic conductivity decreases in the self-assembled ILCs more than the occupied volume of ionic nanodomains. These analyses suggest that the mobility of ions in the self-assembled ILCs remains quite restricted even with small tetrafluoroborate anions because of strong attractive interaction among ionic moieties.

Sustainable generator and in-situ monitor for reactive oxygen species using photodynamic effect of single-walled carbon nanotubes in ionic liquids

Due to the increasing concerns regarding public health and climate change, disinfectant generator technologies that utilize green processes are becoming necessary. It has been confirmed that single-walled carbon nanotubes (SWCNTs) can generate reactive oxygen species (ROS) in aqueous media when illuminated with solar irradiation. However, low efficiency due to competitive reactions between ROS and water and unclear kinetics hinder their potential practical applications. To overcome these limitations, here, SWCNTs were studied in a non-aqueous ionic liquid (IL) to form a suspension system for generating superoxide (O2−) under UV light. The as-obtained O2− from SWCNTs was qualitatively confirmed by electron paramagnetic resonance and UV–vis spectroscopy. The sustainability of the new SWCNTs/IL system was confirmed by UV–vis and Fourier-transform infrared spectroscopy. The IL proved to be an ideal media that could extend the lifetime of O2− from a few microseconds (generated in water) to at least 65 h in the IL. The kinetics of photodynamic effect were investigated by electrochemical characterizations. A new method was established to in-situ monitor the O2− level in the IL system. The O2− level in the IL was quantitatively determined by combining cyclic voltammetry and chronoamperometry techniques. The SWCNTs/IL system generated 4.11 mM of O2− in a mini-scale generator, which was in excess of germicidal levels for ROS. The sustainable, long duration and high-yield of the generator exhibited excellent potential as a generator as well as an in-situ monitor for O2−. This work could pave the way for O2− generation using SWCNTs and promote its applications in air and water disinfection for public health, as well as O2− sensitive chemical sensors for monitoring the environmental quality.

Strength Enhancement of Regenerated Cellulose Fibers by Adjustment of Hydrogen Bond Distribution in Ionic Liquid.

To improve the physical strength of regenerated cellulose fibers, cellulose dissolution was analyzed with a conductor-like screening model for real solvents in which 1-allyl-3-methylimidazolium chloride (AMIMCl) worked only as a hydrogen bond acceptor while dissolving the cellulose. This process could be promoted by the addition of urea, glycerol, and choline chloride. The dissolution and regeneration of cellulose was achieved through dry-jet and wet-spinning. The results demonstrated that the addition of hydrogen bond donors and acceptors either on their own or in combination can enhance the tensile strength, but their effects on the crystallinity of the regenerated fibers were quite limited. Compared with the regenerated fibers without any additives, the tensile strength was improved from 54.43 MPa to 139.62 MPa after introducing the choline chloride and glycerol, while related the crystallinity was only changed from 60.06% to 62.97%. By contrast, a more compact structure and fewer pores on the fiber surface were identified in samples with additives along with well-preserved cellulose frameworks. Besides, it should be noted that an optimization in the overall thermal stability was obtained in samples with additives. The significant effect of regenerated cellulose with the addition of glycerol was attributed to the reduction of cellulose damage by slowing down the dissolution and cross-linking in the cellulose viscose. The enhancement of the physical strength of regenerated cellulose fiber can be realized by the appropriate adjustment of the hydrogen bond distribution in the ionic liquid system with additives.

Micellization and aggregation approach in aqueous amphiphilic ionic liquid and anionic polymer system

In this study, we investigate the aggregation of an ionic liquid (IL), 1-allyl-3-methylimidazolium bromide ([AMIM][Br]) in aqueous solution containing variable amounts of poly(diallyldimethylammonium) chloride (PDADMAc), using conductivity, density, and viscosity techniques in combination with the molecular dynamics simulation approach. The critical micelle concentration (cmc) after micellization for IL in solutions was derived from the conductivity measurements. The effect of PDADMAc on the physicochemical properties of IL in aqueous solution was investigated using comprehensive biophysical techniques such as UV-visible absorption spectroscopy, viscosity (η) and density (ρ) measurements. With the addition of PDADMAc concentration (0, 0.25, 0.05, and 0.1 g.l-1), cmc values increased due to the interaction between IL and PDADMAc. Our UV spectroscopy results showed that the interaction between PDADMAc and [AMIM][Br] was due to the significant differences in the interactions between the amide group of the polymer, the ionic liquid ions, and the water molecules. The apparent molar volumes (V) were calculated from the experimental densities for the (AMIM)(Br)-PDADMAc systems studied. Viscosity data decreased with increasing IL concentration and increased with [PDADMAc]. A computer simulation was used to investigate the aggregate structure between (AMIM)(Br]) and PDADMAc.

The increase in diffraction efficiency of an azobenzene side-chain polymer using imidazolium and ammonium ionic liquids

The advancement of the information age has intensified the focus on photosensitive materials for information storage devices. To develop new photosensitive two azobenzene side-chain polymers i.e., poly(E)-3-(4-((4-nitrophenyl)diazenyl)phenoxy)propyl acrylate (polymer-1) and poly(E)-3-(4-((2-methoxy-4-nitrophenyl)diazenyl)phenoxy)propyl acrylate (polymer-2), were developed, and their diffraction efficiency was evaluated. The impact of ionic liquids (ILs) on the diffraction efficiency was evaluated by combining the polymers with imidazolium and ammonium families of ILs such as 1-butyl-3-methylimidazolium bromide [Bmim]Br, 1-ethyl-3-methyl-imidazolium-bromide [Emim]Br (imidazolium ILs), and triethylammonium methanesulfonate [TMEAS] (ammonium IL). The molecular interaction of both azobenzene side-chain polymers with the ILs was evaluated before the diffraction efficiency studies by employing UV–vis, FT-IR, and confocal Raman spectroscopies. The spectroscopic studies revealed the interaction of the polymers with the imidazolium and ammonium ILs. The mean diffraction efficiency of polymers-1 and −2 were ∼0.05 and ∼0.022%, respectively. After the addition of the ILs, the diffraction efficiency increased. The highest diffraction efficiency was achieved with the polymer-2 + [Emim]Br system of 3.5% and polymer-2 + TEMS combination of 4.03%. Therefore, although the diffraction efficiency of polymer-1 was higher than that of polymer-2, after adding the ILs, the diffraction efficiency of polymer-2 surpassed that of the polymer-1 + ILs system.

Hydrogen bonding on ionic liquid reaction systems

离子液体是由有机阳离子和无机/有机阴离子组成的一类低温熔融盐，具有高度的功能可设计性。氢键作用广泛存在于离子液体体系中，由于静电作用影响，其作用远强于分子体系的氢键作用，因此在化学反应中显示独特的性能。一方面可催化化学反应，实现一系列无金属催化的绿色反应路线；另一方面，可调控反应选择性，高收率获得单一化学品。本文主要总结了近年来关于离子液体体系的氢键作用研究成果，及其催化和调控化学反应的研究进展，并对发展前景进行了展望。

Unravelling the Interactions Prevailing in Mixed Micellar System of Surface-Active Ionic Liquid and Cationic Surfactant

The investigation of mixed micellar behavior of surface-active ionic liquid (SAIL) i.e. 1-butyl-3-methylimidazolium hexadecyl sulfate [C4mim][HS] with cationic surfactant cetyltrimethylammonium bromide (CTAB) has been done to explore the type of interactions prevailing in SAIL/Surfactant mixed system. Thus, the conductometric measurements are performed at (298.15, 308.15 and 318.15) K for various mole fractions of [C4mim][HS]. Different theoretical models like Clint, Rubingh, Motomura and Rodenas have been applied to understand mixed micellar behavior of SAIL/Surfactant mixed system. The value of critical micelle concentrations (cmc), micellar mole fraction based upon various models, ideal critical micelle concentrations (cmc*), interaction parameter (β) and thermodynamic parameters have been evaluated for the mixed systems. The variations of various parameters with respect to temperature and mole fractions give insight to sort of interactions present in studied system.

Effect of pressure on the transport properties of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide and 1-hexyl-3-methylimidazolium tetrafluoroborate

High-pressure self-diffusion and electrical conductivity data are reported for the ionic liquid reference material 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide. The data are used to calculate velocity cross-correlation coefficients and Laity resistance coefficients. High-pressure self-diffusion coefficients are also reported for 1-hexyl-3-methylimidazolium tetrafluoroborate. Comparisons are made with the viscosities using the Stokes-Einstein-Sutherland relation for the two ionic liquids. Density scaling is applied to the transport property measurements and comparison made with earlier studies on ionic liquid systems.

Removal behavior and mechanism of AAEMs and Fe in Zhundong coal under acidic ionic liquid system

China's Zhundong region is rich in coal resources. However, the high content of AAEMs and Fe (Na, Mg, Ca and Fe) in the coal leads to serious equipment fouling and slagging problems during combustion. In this paper, eco-friendly acidic ionic liquid [Bmim]HSO4 was used as a pretreatment solvent for the removal of AAEMs and Fe from Zhundong coal. The effects of [Bmim]HSO4 concentration on the removal of Na, Mg, Ca and Fe were comprehensively investigated. The changes of occurrence modes of four metal elements were systematically analyzed. The removal mechanism of AAEMs and Fe from Zhundong coal was expounded. The results showed that the ash content and B/A of coal treated by [Bmim]HSO4 were significantly lower than those of water leached coal and raw coal. The content of Na2O in coal ash treated by [Bmim]HSO4 was as low as 0.939%, which met the standard of power coal. The removal rate of AAEMs and Fe increased with the increment of [Bmim]HSO4 solution concentration. At the optimum concentration of 5%, the removal rate of Na, Mg, Ca and Fe were 92.89%, 81.11%, 79.31% and 48.27%, respectively. Compared with deionized water, [Bmim]HSO4 solution showed an excellent removal effect on NH4Ac-soluble and HCl-soluble metal elements. It was mainly attributed to the following two points: Firstly, [Bmim]HSO4 destroyed the ionic force and coordination interaction between metal ions and organic oxygen-containing functional groups in coal, carboxylates and phenates were protonated and H+ replaced metal ions. Secondly, the swelling effect of [Bmim]HSO4 on coal was beneficial to the removal of tiny acid soluble minerals embedded in the coal matrix, which further enhanced the removal of AAEMs and Fe in Zhongdong coal by [Bmim]HSO4.

Efficient Production of Adipic Acid by a Two-Step Catalytic Reaction of Biomass-Derived 2,5-Furandicarboxylic Acid.

Efficient catalytic ring‐opening coupled with hydrogenation is a promising but challenging reaction for producing adipic acid (AA) from 2,5‐furan dicarboxylic acid (FDCA). In this study, AA synthesis is carried out in two steps from FDCA via tetrahydrofuran‐2,5‐dicarboxylic acid (THFDCA) over a recyclable Ru/Al2O3 and an ionic liquid, [MIM(CH2)4SO3H]I (MIM=methylimidazolium) to deliver 99 % overall yield of AA. Ru/Al2O3 is found to be an efficient catalyst for hydrogenation and hydrogenolysis of FDCA to deliver THFDCA and 2‐hydroxyadipic acid (HAA), respectively, where ruthenium is more economically viable than well‐known palladium or rhodium hydrogenation catalysts. H2 chemisorption shows that the alumina phase strongly affects the interaction between Ru nanoparticles (NPs) and supports, resulting in materials with high dispersion and small size of Ru NPs, which in turn are responsible for the high conversion of FDCA. An ionic liquid system, [MIM(CH2)4SO3H]I is applied to the hydrogenolysis of THFDCA for AA production. The [MIM(CH2)4SO3H]I exhibits superior activity, enables simple product isolation with high purity, and reduces the severe corrosion problems caused by the conventional hydroiodic acid catalytic system.

Interfacial Properties, Wettability Alteration and Emulsification Properties of an Organic Alkali–Surface Active Ionic Liquid System: Implications for Enhanced Oil Recovery

Combinatory flooding techniques evolved over the years to mitigate various limitations associated with unitary flooding techniques and to enhance their performance as well. This study investigates the potential of a combination of 1-hexadecyl-3-methyl imidazolium bromide (C16mimBr) and monoethanolamine (ETA) as an alkali–surfactant (AS) formulation for enhanced oil recovery. The study is conducted comparative to a conventional combination of cetyltrimethylammonium bromide (CTAB) and sodium metaborate (NaBO2). The study confirmed that C16mimBr and CTAB have similar aggregation behaviors and surface activities. The ETA–C16mimBr system proved to be compatible with brine containing an appreciable concentration of divalent cations. Studies on interfacial properties showed that the ETA–C16mimBr system exhibited an improved IFT reduction capability better than the NaBO2–CTAB system, attaining an ultra-low IFT of 7.6 × 10−3 mN/m. The IFT reduction performance of the ETA–C16mimBr system was improved in the presence of salt, attaining an ultra-low IFT of 2.3 × 10−3 mN/m. The system also maintained an ultra-low IFT even in high salinity conditions of 15 wt% NaCl concentration. Synergism was evident for the ETA–C16mimBr system also in altering the carbonate rock surface, while the wetting power of CTAB was not improved by the addition of NaBO2. Both the ETA–C16mimBr and NaBO2–CTAB systems proved to form stable emulsions even at elevated temperatures. This study, therefore, reveals that a combination of surface-active ionic liquid and organic alkali has excellent potential in enhancing the oil recovery in carbonate reservoirs at high salinity, high-temperature conditions in carbonate formations.

Influence of Polarizability on the Structure, Dynamic Characteristics, and Ion-Transport Mechanisms in Polymeric Ionic Liquids.

We used atomistic simulations and compared the prediction of three different implementations of force fields, namely, the original full partial charge system, the scaled partial charge system, and the Drude oscillator polarizable force field and its effect on the structural and dynamic properties of a polymeric ionic liquid, poly(1-butyl-3-methyl-imidazolium hexafluorophosphate). We found that both the scaled and the polarizable force field models yield comparable predictions of structural and dynamic properties, although the scaled charge model artificially lowers the first-neighbor peak of the radial distribution function and therefore leads to a slight reduction in density. The full charge model was not accurate in its prediction of the dynamic properties but could reproduce the structural properties. With a refined analysis method for the ion-hopping mechanisms, we found that all three methods produce very similar conclusions, namely, that the mobile anion is associated with three cations from two distinct polymer chains and that the fractions of inter- and intramolecular hopping events are comparable. Our results demonstrate that the scaled charge force fields provide a computationally efficient means to capture polarizability effects on both the structural and dynamic properties of polymeric ionic liquid systems.

Toward predicting SO2 solubility in ionic liquids utilizing soft computing approaches and equations of state

BackgroundThe use of novel and green solvents like ionic liquids (ILs) for the capture of air pollutant gases has gained extensive attention in recent years. However, getting reliable and fast predictions of gases solubility in ILs is complex. MethodsFour soft computing methods including deep belief network (DBN), group method of data handling (GMDH), genetic programming (GP), and K-nearest neighbor (KNN) were utilized for estimating the solubility of sulfur dioxide (SO2) in ILs. A total of 374 experimental data points of SO2 solubility in 15 types of ILs were collected and used for model development. Moreover, Valderrama-Patel-Teja (VPT), Zudkevitch-Joffe (ZJ), Peng-Robinson (PR), Redlich-Kwong (RK), and Soave-Redlich-Kwong (SRK) equations of state (EOSs) were applied for the solubility predictions in the SO2 + ILs systems. Significant findingsThe results illustrated that DBN model is the most reliable predictive tool for the SO2 solubility in ILs by having an average absolute percent relative error (AAPRE) of 3.56%. Furthermore, the proposed simple to use GMDH mathematical correlation also provides good estimations with an AAPRE of 8.05%. Despite the weaker performance of the EOSs than the intelligent models, the PR EOS presented better estimations among other EOSs for the SO2 solubility in ILs.