Liquid-liquid Phase Equilibria Research Articles

Customizable cholinium-based aqueous biphasic systems as ecofriendly extraction platform for removal of pesticide from wastewaters

This study explores the use of a series of cholinium ionic liquids (ILs) or salts in combination with polypropylene glycol 400 to form aqueous biphasic systems (ABS) for extracting various polarity pesticides (dicamba, clomazone, pyraclostrobin, and deltamethrin) from water. We assessed five cholinium-based salting-out agents ([Ch][DHP], [Ch]Cl, [Ch][Ac], [Ch][Lac], and [Ch][Nic]), chosen for their structural diversity and unique properties, such as high salting-out potential and different ability to undergo specific interactions. Liquid-liquid equilibrium phase diagrams were established, and partition experiments were conducted to evaluate extraction efficiency. Different partition patterns were obtained for studied pesticides, with [Ch][DHP] demonstrating the highest efficiency exceeding 90 % for each target pesticide due to its strong salting-out ability. On the other hand, more diverse partition trends due to specific interactions were obtained for low-melting cholinium-ILs ABS. The effect of pH and temperature on the partitioning behavior in [Ch][Ac]-based ABS highlighted the cholinium ILs extraction system's customizable nature. Focusing on [Ch]Cl for its eco-friendly aspects, widespread availability and excellent extraction performance, we optimized parameters for the removal of pesticides from real samples, applying the technology to spiked agricultural wastewater with an extraction efficiency of over 99 %. Our findings demonstrate the potential of cholinium-based IL-ABS in reducing environmental pollution through efficient pesticide extraction.

Liquid-liquid phase of imidazolium-based ionic liquids in n-butyl acetate + n-butanol mixtures: Experimental measurements, quality testing, phase stability, thermodynamic modeling

The ester n-butyl acetate is an important chemical compound produced by esterification with n-butanol and used as solvent for pigments, vegetable oils and fats, and in the production of varnishes, coatings, waxes and resins. This work investigated the use of ionic liquids (ILs) as solvents in separation processes involving these substances. The ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]) was synthesized, while 1-ethyl-3-methylimidazolium ethyl sulfate ([EMIM][EtSO4]) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) were purchased. The liquid–liquid equilibrium (LLE) was analyzed based on the experimental measurements (binodal curve, tie-lines), σ-profiles analysis (COSMOTherm), experimental data quality tests, phase stability and thermodynamic modeling with NRTL for the n-butyl acetate + n-butanol + IL ([BMIM][Cl], [EMIM][EtSO4], [EMIM][BF4]) systems at 298.15 K and 101.3 kPa. Experimental results indicated that the studied systems had the LLE phase behavior of type I. Experiments and calculations showed that [EMIM][EtSO4] and [BMIM][Cl] had the best capacities to separate the azeotrope n-butanol and n-butyl acetate. All systems showed separation factors values higher than unity. Low deviations, in the compositions of both liquid phases, indicate that the NRTL model was able to analyze the phase stability and model the phase behavior of the n-butyl acetate + n-butanol + IL systems using gamma-gamma approach.

Thermodynamic and molecular insights into the separation of ethanol/ethyl propionate by extraction using low transition temperature mixtures

Low-transition temperature mixtures (LTTMs) have been proposed as green solvents for the separation of ethanol (EtOH)/ethyl propionate (EtPa) azeotropes. COSMO-SAC model was used to screen LTTMs, and ammonium acetate, ethylammonium chloride, and choline chloride were selected as hydrogen bond acceptors to form LTTMs with ethylene glycol. Liquid-liquid phase equilibrium experiments were carried out for the screened LTTMs and the separation system to confirm the validity of the selected solvents. And the distribution coefficients of EtOH in the three LTTMs were all greater than 1.2, and the selectivity for EtOH ranged from 6 to 50. The separation mechanism at the molecular level was revealed through quantum chemical calculations and wave function analysis. The thermodynamic behavior of the EtOH/EtPa/LTTMs system and the role of hydrogen bonding interactions were systematically investigated. The results indicated that electrostatic forces are the main molecular interactions, and the stronger interaction of LTTMs with ethanol is the basis for achieving the azeotropic separation.

Atomistic modeling of liquid-liquid phase equilibrium explains dependence of critical temperature on γ-crystallin sequence

Liquid-liquid phase separation of protein solutions has regained heightened attention for its biological importance and pathogenic relevance. Coarse-grained models are limited when explaining residue-level effects on phase equilibrium. Here we report phase diagrams for γ-crystallins using atomistic modeling. The calculations were made possible by combining our FMAP method for computing chemical potentials and Brownian dynamics simulations for configurational sampling of dense protein solutions, yielding the binodal and critic temperature (Tc). We obtain a higher Tc for a known high-Tc γ-crystallin, γF, than for a low-Tc paralog, γB. The difference in Tc is corroborated by a gap in second virial coefficient. Decomposition of inter-protein interactions reveals one amino-acid substitution between γB and γF, from Ser to Trp at position 130, as the major contributor to the difference in Tc. This type of analysis enables us to link phase equilibrium to amino-acid sequence and to design mutations for altering phase equilibrium.

The quest for a better solvent for the direct hydration of cyclohexene: From molecular screening to process design

Cylcohexanol is an essential bulk chemical that can be produced via cyclohexene hydration, a liquid-liquid two-phase reaction that is limited by the low reaction rate and the equilibrium conversion. Adding an appropriate solvent is the most promising method to break through these limitations. However, in previous works the solvent was almost blindly selected without a global consideration. In this work, a rational multiscale method is proposed for the effective selection of an economical and sustainable solvent for the direct hydration of cyclohexene. At the molecular scale, liquid-liquid phase equilibrium was estimated using group contribution methods to rapidly screen the potential solvent candidates from a range of organics, based on the partition coefficient. At the reactor scale, the candidates were experimentally investigated to pick out the solvents that could significantly improve the conversion, without introducing side reactions or deactivating the catalyst. At the process scale, the total annual cost (TAC), CO2 emission, and other metrics were calculated to evaluate the eco-efficiency of all solvents. Using this multi-scale method, acetophenone was selected as an eco-efficient solvent from over 100 organics, resulting in the reduction of TAC by 8 % and CO2 emission by 17 % in the production process. Using acetophenone also led to the increase of cyclohexanol yield from 12.3 % to 27.6 % without the occurrence of side reactions and catalyst deactivation.

Separation of n-hexane-ethanol azeotropic mixture using choline chloride +1,4-butanediol deep eutectic solvents

For an environmentally friendly and economical separation process of ethanol from n-hexane which is hard to handle due to the azeotrope, the liquid-liquid extraction was carried out by using choline chloride (ChCl) based deep eutectic solvents (DESs) in different molar ratios with 1,4-butanediol: DES1 (ChCl:1,4-butanediol=1:3), DES2 (ChCl:1,4-butanediol=1:4), and DES3 (ChCl:1,4-butanediol=1:5). The liquid-liquid phase equilibrium was performed on the n-Hexane (1) + Ethanol (2) + DES (3) systems at 298.15 K and atmospheric pressure. The binodal curve is determined by using the turbidity method. The various physico-chemical properties such as refractive index, viscosity, and density were measured for compositions in the binodal point. The equilibrium compositions of liquid-liquid phase equilibrium were determined from the refractive index value at the binodal points, and were predicted by COSMO-SAC model. The miscibility area predicted by COSMO-SAC model became larger as the molar ratio of 1,4-butanediol in DES increased, that is, DES3 shows the most miscible area. While in the experimental results, the miscibility depending on DES-type does not show a large difference. The experimental values for PI shows the order of DES2 (ChCl:1,4-butanediol=1:4)> DES1 (ChCl:1,4-butanediol=1:3)> DES3 (ChCl:1,4-butanediol=1:5) at less 3 wt% concentration of ethanol, but at higher concentration range (>3 wt%) DES3 shows the best value. Both of DES2 and DES3 are profitable to adopt in the extraction process of ethanol from n-hexane owing to the high performance index, high distribution coefficient, and high selectivity. The experimental results show the possibility of DESs as an alternative to ionic liquids in the separation of azeotropic mixtures, taking into account the properties of DES such as low price, uncomplicated manufacturing methods, environmentally friendly, and low toxicity.

Atomistic modeling of liquid-liquid phase equilibrium explains dependence of critical temperature on G-crystallin sequences.

Atomistic modeling of liquid-liquid phase equilibrium explains dependence of critical temperature on G-crystallin sequences.

Liquid-liquid phase equilibrium measurement and thermodynamic modeling for the separation of n-hexane and methanol with four solvents

To solve the problem of generating n-hexane in the industrial production of methanol, four common and inexpensive solvents {dimethyl sulfoxide, 1,2-propanediol, furfuryl alcohol, and furfural} were chosen as extractants to separate n-hexane and methanol. The liquid–liquid equilibrium (LLE) data of n-hexane + methanol +{dimethyl sulfoxide, 1,2-propanediol, furfuryl alcohol, or furfural} were measured at 303.2 K and 101.3 kPa. The extraction performance of four extractants was evaluated by the distribution coefficient (D) and separation factor (S). At the same time, NRTL and UNIQUAC models were used to fit the experimental LLE data to obtain regression parameters. The reliability of the binary interaction parameters was verified by the mixed surface analysis based on Gibbs energy topology. The root mean square deviation (RMSD) of the NRTL and UNIQUAC models are less than 0.0040 and 0.0057, respectively, indicating that the NRTL and UNIQUAC models are suitable for the study of this system. Furthermore, the interaction energy between extractant and methanol molecules was analyzed by the DMol3 module and the effect difference of liquid–liquid extraction was explained from the perspective of interaction energy using σ-Profile.

Liquid-liquid equilibrium and insights of intermolecular interactions for separation of isopropyl acetate + isopropanol by imidazolium-based ionic liquids

BackgroundDuring the production of isopropyl acetate (IPAC), a mixture of IPAC and isopropanol (IPA) can be produced. Because IPAC and IPA can form a minimum azeotropic mixture with the azeotropic temperature of 354.08 K, it is difficult to separate such a mixture. In this work, liquid-liquid extraction is considered to separate the mixture of IPAC and IPA. Herein, the liquid-liquid equilibrium (LLE) data was determined and correlated for the separation of IPAC and IPA. MethodsFor separating IPAC and IPA by extraction, three ionic liquids (ILs) 1-ethyl-3-methyl-imidazolium hexafluorophosphate, 1‑butyl‑3-methyl-imidazolium hexafluorophosphate and 1‑butyl‑3-methyl-imidazolium dihydrogen phosphate were selected as extractants. The liquid-liquid equilibrium phase behavior of ternary mixtures (IPAC + IPA + ILs) at 298.15 K was investigated. The distribution functions of charge density and interaction energy were determined by the COSMO-SAC model and Dmol3 in Materials Studio, and the interactions between molecules were explored. Significant findingsThe experimental data showed that the three ILs can extract IPA from the mixture of IPAC and IPA and the IL [Bmim][H2PO4] has a better extraction ability compared to the other ILs. The measured LLE data were fitted using the NRTL model and the interaction parameters were regressed, which is a favor in separating the mixture for industrial practice.

Simultaneous prediction of vapor-liquid and liquid-liquid phase equilibria in systems of ionic liquids belonging to [Cnmim][BF4] and [Cnmim][PF6] families by CP-PC-SAFT and SAFT-VR-Mie with universal kij values

This study examines the capabilities of CP-PC-SAFT and SAFT-VR-Mie without association, polar and electrostatic contributions to predict phase equilibria in the systems of ionic liquids (ILs) [Cnmim][BF4] and [Cnmim][PF6] (2 ≤ n ≤ 12). The molecular parameters of both models for these ILs were generalized by the 1st order polynomials as functions of molecular weights. The models were fitted to VLE in the system CO2 – [C4mim][BF4]. k12 = 0.04 was obtained for CP-PC-SAFT and k12 = 0.03 – for SAFT-VR-Mie. These values of the binary parameters were applied for predicting phase equilibria in other systems of CO2, N2O, CH4, O2, CO, C3H8 and vinyl chloride with the considered ILs. It was found that both models exhibit robust and far-going predictive capacities. SAFT-VR-Mie was found superior in predicting the available data on LLVE compositions in the systems of CO2 and N2O. CP-PC-SAFT was more accurate in estimating the densities of saturated phases. Some VLE data were predicted more accurately by SAFT-VR-Mie and others – by CP-PC-SAFT. Both models correctly estimate that the ranges of LLE phase splits increase in the sequence of thiophene → benzene → toluene → xylenes → n-alkanes and yielded reasonably good results for phase equilibria and densities of saturated phases in ternary systems of the considered ILs with aliphatic and aromatic hydrocarbons. At the same time, the overall accuracy of CP-PC-SAFT in predicting the available binary LLE data was better. With the universal value of k12 = 0.04 this model precisely predicts the UCST in the system aniline-[C4mim][BF4].

Insight into solid-liquid and liquid-liquid phase equilibrium behavior of vanillin and ethyl vanillin

How different solute affects solid-liquid equilibrium and the underlying mechanisms of how solutes are partitioned in the liquid-liquid two phases during crystallization are not well understood, which setting up obstacles to better control of the crystallization and purification process. Thus, firstly, we uncover how the solvent composition and solute structure affect the phase equilibrium of vanillin (VA) and ethyl vanillin (EVA) in n-propanol-water mixed solvent. The results show that both the solubility of VA and EVA show significant co-solvency phenomenon. Besides, stronger hydrophobicity of EVA leading to lower solubility than that of VA. Furthermore, we found that the ratio of relative contribution of enthalpy and entropy decreases with increasing n-propanol content. Secondly, ternary phase diagrams indicate that EVA is more prone to liquid-liquid phase separation (LLPS) than VA, since EVA possesses greater steric hindrance and stronger hydrophobicity. Interestingly, the LLPS curves are mainly dependent on solute and solvent properties but almost independent of temperature in both systems. Meanwhile, the tie lines are found to be not strictly parallel to each other, which suggest that solute clusters exist in the lean solute phase satisfying the optimal stable ratio and the rich solute phase satisfying the suboptimal stable ratio. Finally, molecular simulation showed that the energy of the LLPS system is always lower than that of the homogeneous solution system. These contributions provide in-depth understanding of the solid-liquid and liquid-liquid phase behavior, which is expected to provide theoretical guidance for breaking through the bottleneck of crystallization control.

Effect of solvent and temperature on the phase equilibrium behavior of hydroxylamine sulfate in water-ethanol mixed solvents: Solubility and ternary liquid-liquid equilibrium diagram with liquid-liquid equilibrium

The thermodynamic properties of hydroxylamine sulfate (HAS) in binary mixed solvents of water-ethanol were investigated in this work. Experimental results indicated that a temperature above 323.15 K will bring about the occurrence of liquid-liquid phase separation in the water-ethanol-HAS system. Solubility of HAS in water and ethanol-water binary mixed solvents was experimentally determined from 283.15 to 323.15 K under atmospheric pressure (101.3 kPa) by employing a gravimetric method. As the mass fraction of water in the mixed solvent increase, there is an increase in the solubility of HAS. In addition, the solubility of HAS is positively dependent on the temperature. Furthermore, the modified van’t Hoff model, Apelblat model, van’t Hoff − Jouyban − Acree model, and Apelblat − Jouyban − Acree model were used to correlate the experimental solubility of HAS, and the Apelblat model showed the best agreement. Besides, the van't Hoff equation was utilized to evaluate the thermodynamic parameters of HAS in binary solvents, calculation results confirm that these dissolving processes are endothermic and entropy-driving. Ternary phase diagrams with liquid-liquid equilibrium at 324.15, 328.15 and 333.15 K were constructed, and the boundaries of each phase area of the ternary phase diagram were verified at 333.15 K. As for the water-ethanol-HAS system, the temperature has an influence on the phase zone of the ternary phase diagram by affecting solid-liquid phase equilibrium. However, the temperature has no effect on the liquid-liquid phase equilibrium. The nucleation process of oiling-out crystallization of HAS was determined to follow a two-step mechanism: the liquid-liquid phase separation is generated at first, and then nucleation occurred and crystals subsequently grow in the aqueous phase.

Liquid-liquid phase equilibrium and interaction exploration for separation 2-methoxy-phenol and water with different solvents

To recover 2-methoxy-phenol in water, C5-C8 alkyl alcohols were selected as extractants to separate water and 2-methoxy-phenol. The liquid–liquid equilibrium (LLE) data for water + 2-methoxy-phenol + {1-pentanol, 1-hexanol, 1-heptanol or 1-octanol} were explored in 303.2 K under 101.3 kPa. The extraction performance of four extractants was assessed through the distribution coefficient (D) and separation factor (S). Meanwhile, the NRTL and UNIQUAC models were used to correlate and fit the data to obtain regression parameters. Furthermore, the mixed surface analysis based on Gibbs energy topology verified that the binary interaction parameters are consistent with the measured data. The LLE data were also predicted through the COSMO-UNIFAC model. The root mean square deviation (RMSD) of the three models do not exceed 0.0023, 0.0030, and 0.0234, respectively, indicating that the NRTL and UNIQUAC models are suitable for the correlation of the studied system and the COSMO-UNIFAC model can be the way to predict the LLE data of the researched system within the scope of this work. In addition, the interaction and interaction energy between component molecules were studied through the DMol3 module.

Effect of the ionic liquids on extraction of aromatic and sulfur compounds from the model petrochemical stream

Suitability of a imidazolium ionic liquids (ILs) as solvents in dearomatization and desulfurization in the ternary systems and in a model multicomponent systems has been analyzed. With this aim, ternary liquid-liquid phase equilibrium data (LLE) have been obtained for ternary mixtures of {IL + benzene, or toluene, or thiophene, or 2-butanethiol + hexane}, or {IL + benzene + 2-methylpentane} at T = 298.15 K and ambient pressure, as well as for multicomponent systems – model petrochemical stream {IL + model stream (benzene, toluene, thiophene, 2-butanethiol) + hexane} at T = 303.15 K and ambient pressure. Two ILs have been studied: 1-ethyl-3-methylimidazolium thiocyanate, [EMIM][SCN] and 1-ethyl-3-methylimidazolium dicyanamide, [EMIM][DCA]. The values of solute distribution ratio and selectivity have been evaluated. It has been shown that ILs investigated in this work are able to extract sulfur compounds in preference to benzene and toluene. The solute distribution ratios for both ILs are similar. The selectivity of the aromatic and sulfur compounds are higher for [EMIM][SCN]. The best distribution ratio (>1.98) and selectivity (>242) was observed for thiophene extracted from the model stream 1:1.

Extraction of allyl alcohol from its aqueous solution using two different ionic liquids: Intermolecular interaction and liquid-liquid phase equilibrium explorations

Allyl alcohol is a remarkable chemical intermediate. During its preparation by allyl acetate hydrolysis, an aqueous mixture is usually obtained. Because allyl alcohol can form a minimum boiling point azeotropic mixture with water, it is impossible to separate such a mixture by conventional distillation. In this work, for recovering allyl alcohol by extraction, the ionic liquid extractants (ILs) were adopted by the model of COSMO-SAC and two ILs 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP][Tf2N]) and 1-octyl-3-methylimidazolium trifluoromethanesulfonate ([OMIM][OTf]) were selected. The length of the hydrogen bond and the energy of the interaction between the ILs and (allyl alcohol/water) were calculated by quantum chemical calculations. The experimental liquid–liquid phase equilibrium (LLE) data for the ternary systems (water + allyl alcohol + [OMIM][OTf]/[BMP][Tf2N]) were explored at 298.15 K. The [OMIM][OTf] and [BMP][Tf2N] extraction capability was assessed with selectivity and partition ratio. In addition, the NRTL model was used to fit the measured tie-line values.

Thermodynamic representation of ionic liquids phase equilibrium with PDH-ASOG and PDH-UNIFAC models

The systematic study of thermodynamic properties for understanding liquid-liquid equilibrium (LLE) behavior of Ionic Liquids (ILs) is an important research direction. The predictive thermodynamic models are useful tools in this area. However, the optimization problem in this kind of predictive modelling can be very challenging. This work proposes a hybrid optimization method for handling such problems. This method benefits from the robustness of Genetic Algorithm (GA) as a global search technique while complementing it with local search abilities of Nelder-Mead Algorithm (NMA). The proposed algorithm showed quite promising results in estimating the interaction parameters of four thermodynamic models: UNIFAC, ASOG, PDH-UNIFAC and PDH-ASOG. In these models, the long-range contribution is accounted by Pitzer–Debye–Hückel (PDH) equation while the short-range contribution is considered by nonelectrolyte UNIFAC and ASOG. Particularly, LLE phase behavior of two ILs comprising of sulfate-based anions and imidazolium cations is examined for 44 ternary (421 tie-line) systems and the full set of computed parameters by the proposed hybrid method is reported.

Размерный эффект при фазовом равновесии жидкость-жидкость в трехкомпонентной системе

The size effects during phase transformations in systems of submicro- and manometer sizes are expressed in significant changes in phase equilibria. Examples of ternary phase diagrams small volume systems in the literature are virtually absent. The size effect is demonstrated by creating a series of phase diagrams of an aniline-methylcyclopentane-hexane solution. The liquid-liquid phase equilibrium was simulated by the methods of chemical thermodynamics for particles (droplets) with a core-shell configuration with a radius of 100 and 50 nm at temperatures of 25 and 45^oC. Reducing the volume of this system is accompanied by a change in the heterogeneous region, the appearance of metastable states that are absent in the macrophase, and increase the thermodynamic stability of the homogeneous solution.

Azeotropic separation of isopropanol-water using natural hydrophobic deep eutectic solvents

Inspired by the use of natural precursors for hydrophobic deep eutectic solvents (DESs) synthesis, in this work five different hydrophobic natural DESs have been prepared for azeotropic separation of IPA-water. The prepared natural hydrophobic DESs are also sustainable solvents having a low viscosity (≤50 mPa.s), high thermal degradation temperature (≥150 °C), and the density difference between water and the DESs are more than 50 kg m−3. The spectroscopy techniques such as H1NMR and FTIR were used to verify the formation of DESs. The pseudo-ternary liquid-liquid equilibrium phase diagram of isopropanol-water-DESs systems was then explored to study the extraction ability of synthesized DESs. The results show that all the DESs form type I ternary LLE diagram having broader immiscibility region with positive tie-line slopes and binodal curves depends upon the precursors used for the synthesis of hydrophobic DESs. In addition, the binary parameters for the extraction of IPA form water using natural hydrophobic were calculated using NRTL thermodynamic model.

Liquid-liquid equilibria and mechanism exploration for the extraction of sulfides from FCC naphtha via organic solvent as extractant

Separation of sulfides from fluid catalytic cracking (FCC) naphtha is of great significance for environmental protection. In this work, the organic solvents N-methyl-2-pyrrolidone (NMP), sulfolane (SUL), and their mixtures were selected to extract sulfides (3-methylthiophene) from model FCC naphtha (n-heptane). Correspondingly, the liquid-liquid phase equilibrium (LLE) data of the systems n-heptane +3-methylthiophene + SUL/NMP/(NMP + SUL) were experimentally obtained at 298.15 K and 101.3 kPa. The distribution coefficient and separation factor were calculated to assess the extraction performance of the solvents. The results showed that mixed solvent (NMP + SUL) could be used as a potential solvent to extract 3-methylthiophene due to its suitable selectivity and solubility. Meanwhile, the density functional theory (DFT) method was applied to explore the extraction mechanism of 3-methylthiophene from n-heptane by NMP or SUL. Electrostatic potential (ESP) analysis, interaction energies, and reduced density gradient (RDG) analysis showed that the main interactions between NMP/SUL and 3-methylthiophene were van der Waals and weak hydrogen bond forces. In addition, the LLE data were correlated by the NRTL and UNIQUAC thermodynamic models with the RMSD values were all <0.30%. Also, the binary interaction parameters were regressed which could be applied for the optimization and design of the separation process.

A comparative study on liquid phase equilibria of aqueous mixtures of two structurally close carboxylic acids with sec-amyl alcohols at 298.2 K

This research reports the results of measurements on liquid-liquid equilibrium (LLE) for the four ternary systems of (water + butyric or 3-methylbutyric acids + sec-amyl alcohol) and (water + butyric or 3-methylbutyric acids + sec-isoamyl alcohol) at 298.2 K and 0.1 MPa. According to the measured solubility and tie-line data, the related phase diagrams for the studied systems were plotted. Due to the strong structural similarity of the studied system's constituents, the influence of the chemical structures of the acids and the solvents on the LLE behavior was comparatively studied. The ternary systems display two forms of LLE phase diagrams. The aqueous systems of butyric acid and the two structural isomers (sec-amyl alcohol and sec-isoamyl alcohol) exhibit type-1 phase behavior of LLE, whereas the type-2 behavior was observed for the systems containing the branched chain carboxylic acid (3-methylbutyric acid). The activity coefficients models of UNIQUAC and NRTL fit the measured tie line-data. According to the measured LLE data, the values of the models' binary interaction parameters were optimized using MATLAB Fminsearch function. Based on the experimental data, the mass distribution coefficients and selectivity were evaluated and systematically compared for the studied systems. Finally, reliability of the obtained NRTL parameters was checked using topological analysis connected to the Gibbs tangent plane test.