Universal Functional Group Activity Coefficient Research Articles

Surface tension of binary and ternary mixtures mapping with ASP and UNIFAC models based on machine learning

Modeling predictions of surface tension for binary and ternary liquid mixtures is difficult. In this work, we propose a machine learning model to accurately predict the surface tension of binary mixtures of organic solvents-ionic liquids and ternary mixtures of organic solvents-ionic liquids–water and analytically characterize the proposed model. In total, 1593 binary mixture data points and 216 ternary mixture data points were collected to develop the machine learning model. The model was developed by combining machine learning algorithms, UNIFAC (UNIversal quasi-chemical Functional group Activity Coefficient) and ASP (Abraham solvation parameter). UNIFAC parameters are used to describe ionic liquids, and ASP is used to describe organic solvents. The effect of each parameter on the surface tension is characterized by SHAP (SHapley Additive exPlanation). We considered support vector regression, artificial neural network, K nearest neighbor regression, random forest regression, LightGBM (light gradient boosting machine), and CatBoost (categorical boosting) algorithms. The results show that the CatBoost algorithm works best, MAE = 0.3338, RMSE = 0.7565, and R2 = 0.9946. The SHAP results show that the surface tension of the liquid decreases as the volume and surface area of the anion increase. This work not only accurately predicts the surface tension of binary and ternary mixtures, but also provides illuminating insight into the microscopic interactions between physical empirical models and physical and chemical properties.

Predicting viscosity of ionic liquids - water mixtures by bridging UNIFAC modeling with interpretable machine learning

Predicting the viscosity of ionic liquids (ILs)-water mixtures precisely is considerable for diversity applications in chemical industries. In this work, interpretable machine learning models incorporate physics information developed to link the UNIversal quasi-chemical Functional group Activity Coefficient (UNIFAC) models as new predictive tools for the viscosity of ILs-water mixtures. Machine learning algorithms including Adaptive Boosting (AdaBoost), Categorical Boosting (CatBoost), Extreme Gradient Boosting (XGBoost), K-Nearest-Neighbour Regression (KNNR) and Random Forest (RF) are compared, with the Catboost model achieving the best accuracies (RMSE = 0.0084, MSE = 0.0001, MAE = 0.0020, R2 = 0.9941). We demonstrate that the UNIFAC model and the Stokes-Einstein relation assisted to reduce the feature dimensionality, and improve the predictive power of the viscosity of ILs-water mixtures. The describe of the Shapley’s additive explanations (SHAP) and Partial dependence plots (PDP) are giveing expression to the features importance of the UNIFAC model. Our work created a new paradigm to hyperlink the machine learning models with ILs-related properties, the UNIFAC model contains prior physical information to optimize the features of the experiment, and fill the gap of the input features and the viscosity of ILs-water mixtures.

Designing and Characterization of Low-Temperature Eutectic Phase Change Materials Based on Alkanes

The research presented here focuses on investigating the relationship between the structure of components and the eutectic temperature of binary systems designed as phase change material (PCM). For two-component systems containing long-chain alkanes (n-tetradecane, n-pentadecane, n-hexadecane, or n-heptadecane) and decanoic acid or 1-decanol, experimental data of the solid–liquid equilibrium are presented. The collected data were used to determine the composition and temperature of eutectic mixtures that are promising PCMs with a narrow melting point range. An essential aspect of this work is to confirm the possibility of determining eutectics of similar systems using predictive models, mainly the modified Dortmund universal quasichemical functional group activity coefficients method, without the need to perform expensive and time-consuming experimental research. The experiments were supplemented with the physicochemical characteristics (density and viscosity) of the liquid mixtures. The obtained PCM was closed in a polymer matrix to prevent material leakage into the environment, and the obtained composite materials were characterized by using scanning electron microscopy and differential scanning calorimetry techniques.

Modeling, simulation, and optimization for producing ultra-low sulfur and high-octane number gasoline by separation and conversion of fluid catalytic cracking naphtha

Contradiction between the desulfurization and loss of octane number (ON) for fluid catalytic cracking (FCC) naphtha is the long-term problem of clean gasoline production. Moreover, ON loss is substantially aggravated during deep hydrodesulfurization because of the global limited supply of sulfur for gasoline. This paper introduced a novel process for ultra-clean gasoline production that solves the above problem by using a unique separation approach. The components were separated by the coupling of distillation and solvent extraction, which the separation efficiency depends on the relationship between solvent and feedstock components. However, the compositions of FCC naphtha are complicated and always changing due to different processing technologies. Therefore, changes in the material composition must be considered during production. In this study, ternary liquid–liquid equilibrium (LLE) was explored to investigate the interaction of olefin, sulfide, and sulfolane solvent. A universal quasi-chemical functional group activity coefficient (UNIFAC) group contribution model was selected to predict the product composition when the FCC naphtha was treated by this process. The lack and necessity of group interaction parameters for the prediction were obtained through the regressive calculation of LLE results. A simulation method was established by Aspen Plus, and the reliability was well illustrated. Finally, the high olefin content of FCC naphtha critical components was analyzed by this simulation method. The sulfur and olefin levels of the product were 9.0 mg/kg and 18.6 wt%, respectively. The operation conditions simulated using the proposed technique met the requirements for the latest commercial gasoline worldwide.

Hygroscopic growth of aerosol particles consisted of oxalic acid and its internal mixture with ammonium sulfate for the relative humidity ranging from 80% to 99.5%

The hygroscopicity of atmospheric aerosol particles plays an important role in their effects on the environment and the public health. Oxalic acid (OA) has been recognized as the dominant dicarboxylic acid in the urban and the remote aerosol particles, so a number of studies have investigated the hygroscopicity of aerosols consisted of pure OA and its mixture with inorganic salt. However, few experimental studies have focused on the hygroscopicity of nanoscale particles at high relative humidity (RH) below saturation of water vapor (i.e., RH = 90–100%) due to the limitation of traditional measuring instruments. In this work, the hygroscopic growth factor (GF) of the aerosol particles composed of pure OA and internally mixed OA-ammonium sulfate (AS) at RH = 80–99.5% were studied using a high humidity tandem differential mobility analyzer (HHTDMA). The experimental results were used to verify the applicability of models including the ideal solution model, the extended aerosol inorganics model (E-AIM) combining with the revised universal quasi-chemical functional group activity coefficients (UNIFAC-Peng) model, the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model and the Zdanovskii–Stokes–Robinson (ZSR) model. According to the experimental results, the effect of RH, the composition and the initial dry particle diameter (D0) on the hygroscopic growth factor (GF) and the effective hygroscopicity parameter (κ) of particles at RH = 80–99.5% were analyzed in details. It has been found that for pure OA particles with D0 = 80/100 nm, the prediction of the UNIFAC-Peng model and the AIOMFAC model becomes more accurate than the ideal solution model with the increasing of RH, while all models cannot describe the GF of smaller particles at RH = 80–99.5%. For mixed OA-AS aerosol particles, the chemical reaction is an important reason for the discrepancies between the HHTDMA results and the model prediction. For the pure OA aerosol particles at RH ≤ 96% and particles containing AS at RH ≤ 99.5%, the sensitivity of GF to D0 is positively and negatively correlated with RH and D0, respectively. However, for all aerosol types in this study, the sensitivity of GF to RH is positively correlated with both D0 and RH. In addition, the κ based on the measurement is clearly dependent on D0 (at RH = 95–99.5%), RH and the particle composition (at RH = 80–99.5%). The measured hygroscopicity of aerosol particles at high RH might be useful in addressing challenges in solving the discrepancies between the κ measured under subsaturated and supersaturated conditions.

Artificial neural network approach for predicting blood brain barrier permeability based on a group contribution method

Background and ObjectiveThe purpose of this study was to develop a quantitative structure-activity relationship (QSAR) model for the prediction of blood brain barrier (BBB) permeability by using artificial neural networks (ANN) in combination with molecular structure and property descriptors. MethodsUsing a database composed of 300 compounds, 52 structure descriptors obtained based on the universal quasichemical functional group activity coefficients (UNIFAC) group contribution method and the selected 8 molecular property descriptors were used as the network inputs, whereas logBB values of compounds constituted its output. ResultsThe correlation coefficient R of the constructed prediction model, the relative error (RE) and the root mean square error (RMSE) was 0.956, 0.857, and 0.171, respectively. These indicators reflected the feasibility, robustness and accuracy of the prediction model. Compared with the previously published results, a significant improvement in the predictions of the proposed ANN model was observed. ConclusionsANN model based on the group contribution method could achieve a satisfactory performance for logBB prediction.

Isolation of potential α-glucosidase inhibitor from Inonotus obliquus by combining ultrafiltration-liquid chromatography and consecutive high-speed countercurrent chromatography.

Inonotus obliquus is a rare medicinal fungus that contains several potential therapeutic ingredients. In this study, the α-glucosidase inhibitory activity of I. obliquus was examined, and a potential α-glucosidase inhibitor, (E)-4-(3,4-dihydroxyphenyl)but-3-en-2-one, was isolated from the I. obliquus extract through ultrafiltration-liquid chromatography (UF-LC). Consecutive high-speed countercurrent chromatography (HSCCC) was used for separation to obtain large quantities of the target compound. The universal quasi-chemical functional group activity coefficient (UNIFAC) model was utilized to prepare a two-phase solvent system, n-hexane/ethyl acetate/ethanol/water (4 : 4.5 : 3.5 : 5, v/v/v/v), wherein the proportions of n-hexane/ethyl acetate/ethanol/water in the stationary and mobile phases were 19.8 : 19.7 : 7.9 : 2.2 (v/v/v/v) and 1 : 16.4 : 57.5 : 136.6 (v/v/v/v), respectively. A flow rate of 2.5 mL min-1 and a column speed of 860 rpm were maintained. Consequently, 10.3 mg of the target compound (95.9% purity) was obtained from 900 mg (6 × 150 mg) of the I. obliquus extract. The use of the UNIFAC model, in combination with consecutive HSCCC separations, allows the purification of large quantities of samples over a short time. Furthermore, the volume of the organic solvent required is reduced. Thus, UF-LC is an effective technique for screening potential α-glucosidase inhibitors isolated from I. obliquus. This can ultimately aid in the discovery of bioactive compounds for the prevention and treatment of diabetes.

Alcohol Dehydration by Extractive Distillation with Use of Aminoethers of Boric Acid

Aminoethers of boric acid (AEBA) were studied as potential extractants for the separation of aqueous–alcoholic azeotropic mixtures by extractive distillation. The conditions of vapor–liquid equilibrium in aqueous solutions of ethanol and isopropanol in the presence of AEBA were studied. The division of AEBA molecules into group components was proposed, and previously unknown geometric parameters of the boron group and the energetic pair parameters of the boron group with the alkane group, ether group, amine-3d group, and alcohol group were determined within the framework of the Universal Functional Group Activity Coefficient (UNIFAC) model. The modeling of the extractive rectification process of an ethanol–water mixture with AEBA as extractant has been carried out. The dependences of the cost function on the extractant flow rate, the residual water content in it and the number of theoretical trays were obtained. A technological scheme for ethanol dehydration has been proposed, and its technological characteristics have been calculated.

Transesterification of triolein and methanol with Novozym 435 using co-solvents

To enhance the reaction rate and yield during biodiesel synthesis with Novozym 435 (an immobilized lipase), a co-solvent method was applied, after which the relationships between reaction time and reaction yield during the single-phase enzymatic transesterification of triolein and methanol in the presence of co-solvents such as tetrahydrofuran, acetone, and hexane were investigated. The addition of hexane led to inactivation of Novozym 435, whereas in the presence of acetone or tetrahydrofuran, the reaction was accelerated and the yield was higher than with a conventional solvent-free enzymatic reaction. There was a clear difference in the dispersion of Novozym 435 particles between with and without co-solvents. The co-solvents prevented particle aggregation from occurring during the reaction without co-solvent. This is the likely reason for the enhanced reaction yield in the presence of co-solvents. To better understand the difference among the co-solvents employed, we estimated phase compositions during transesterification using the LLE (liquid-liquid equilibrium)-UNIFAC (UNIversal quasichemical Functional group Activity Coefficients) model, and examined the effect of these compositions on the reaction and dispersion of the glycerin by-product phase. Using the model, we also accounted for why hexane led to inactivation by estimating the transfer free energy of methanol, glycerin, and water between the initial bulk reaction solution and the water layer on the enzyme surface.

Blended E85–Diesel Fuel Droplet Heating and Evaporation

The multidimensional quasi-discrete (MDQD) model is applied to the analysis of heating and evaporation of mixtures of E85 (85 vol % ethanol and 15 vol % gasoline) with diesel fuel, commonly known as “E85–diesel” blends, using the universal quasi-chemical functional group activity coefficients model for the calculation of vapor pressure. The contribution of 119 components of E85–diesel fuel blends is taken into account, but replaced with smaller number of components/quasi-components, under conditions representative of diesel engines. Our results show that high fractions of E85–diesel fuel blends have a significant impact on the evolutions of droplet radii and surface temperatures. For instance, droplet lifetime and surface temperature for a blend of 50 vol % E85 and 50 vol % diesel are 23.2% and up to 3.4% less than those of pure diesel fuel, respectively. The application of the MDQD model has improved the computational efficiency significantly with minimal sacrifice to accuracy. This approach leads to a s...

Experimental study of the LL, VL and VLL equilibria of water + 1-butanol + 2-octanol at 101.3 kPa

Equilibrium data for the water + 1-butanol + 2-octanol system is determined in this work. Liquid-liquid equilibrium (LLE) data are obtained at 303.15 K and 313.15 K, with a view to investigating the influence of temperature.Vapour-liquid-liquid equilibrium (VLLE) and vapour-liquid equilibrium (VLE) data of the same system are also determined at 101.3 kPa, by means of a modified Fisher Labodest recirculating still that is coupled to an ultrasonic probe. Additionally, the heterogeneous binary azeotrope of the pair water + 2-octanol is determined.Correlation parameters are obtained from the experimental results for use in the universal quasichemical (UNIQUAC) and non-random two-liquid (NRTL) thermodynamic models in CHEMCAD 7. The UNIQUAC, NRTL and original universal functional group activity coefficient (UNIFAC) models are then, in turn, used to predict the LLE and VLLE data from these correlation parameters.

Screening Monoethanolamine As Solvent to Extract Phenols from Alkane

Coal tar is a byproduct of low temperature coal carbonization. The separation of the compounds has great significance since its main component is the mixture of phenols and hydrocarbons. In this paper, the separation of specific phenolic compounds from model coal tar (phenols + hexane) was studied. The solvent was screened by empirical analysis, the universal quasichemical functional group activity coefficient (UNIFAC), and conductor-like screening model COSMO-SAC (segment activity coefficient). COSMO-SAC was used to calculate the capacity, selectivity, and performance index of solvents. Finally, the monoethanolamine (MEA) was selected as the solvent to extract the phenols. The liquid–liquid equilibrium for the ternary mixture of phenols + hexane + MEA was measured at 303.15 K and 323.15 K under atmospheric pressure, and the results showed that MEA provided a high distribution coefficient, efficiency, and selectivity for phenols. Meanwhile, the extraction process of phenols was simulated based on the nonrandom two-liquid (NRTL) model, for which binary interaction parameters were obtained through calculations of phase equilibrium. The results showed that the purity of phenols can achieve more than 99.5 wt % using MEA as a solvent.

Continuous countercurrent liquid–liquid extraction method for the separation of 2,3-butanediol from fermentation broth using n-butanol and phosphate salt

In this study, we examined continuous countercurrent liquid–liquid extraction (CC-LLE) of 2,3-butanediol (BDO) from synthetic (BDO+water) and fermented broth solutions in a bubble column using n-butanol as an extractant solvent. To elucidate salting-out effect on the extraction feasibility of BDO, CC-LLE experiments were also conducted for synthetic and fermented BDO solutions by adding 10wt% K2HPO4 salt to the aqueous feed. Distribution coefficients, volumetric mass transfer coefficients, number of equilibrium stages, minimum solvent requirement, and extraction efficiencies were determined from the CC-LLE experiments for three different concentrations of BDO in feed. The results showed that addition of phosphate salt to the aqueous feed increased the BDO extraction efficiency by 81.8% for synthetic BDO solution and by 30% for fermented BDO solution at 2.5wt% BDO in feed. Furthermore, modeling of CC-LLE for synthetic BDO solution using a newly parameterized UNIFAC-LL (Universal Functional Group Activity Coefficient – Liquid–Liquid) method within the Aspen Plus simulation program predicted that 99% BDO extraction efficiency can be achieved with 6 theoretical equilibrium stages.

The Secondary Organic Aerosol Processor (SOAP v1.0) model: a unified model with different ranges of complexity based on the molecular surrogate approach

Abstract. In this paper the Secondary Organic Aerosol Processor (SOAP v1.0) model is presented. This model determines the partitioning of organic compounds between the gas and particle phases. It is designed to be modular with different user options depending on the computation time and the complexity required by the user. This model is based on the molecular surrogate approach, in which each surrogate compound is associated with a molecular structure to estimate some properties and parameters (hygroscopicity, absorption into the aqueous phase of particles, activity coefficients and phase separation). Each surrogate can be hydrophilic (condenses only into the aqueous phase of particles), hydrophobic (condenses only into the organic phases of particles) or both (condenses into both the aqueous and the organic phases of particles). Activity coefficients are computed with the UNIFAC (UNIversal Functional group Activity Coefficient; Fredenslund et al., 1975) thermodynamic model for short-range interactions and with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) parameterization for medium- and long-range interactions between electrolytes and organic compounds. Phase separation is determined by Gibbs energy minimization. The user can choose between an equilibrium representation and a dynamic representation of organic aerosols (OAs). In the equilibrium representation, compounds in the particle phase are assumed to be at equilibrium with the gas phase. However, recent studies show that the organic aerosol is not at equilibrium with the gas phase because the organic phases could be semi-solid (very viscous liquid phase). The condensation–evaporation of organic compounds could then be limited by the diffusion in the organic phases due to the high viscosity. An implicit dynamic representation of secondary organic aerosols (SOAs) is available in SOAP with OAs divided into layers, the first layer being at the center of the particle (slowly reaches equilibrium) and the final layer being near the interface with the gas phase (quickly reaches equilibrium). Although this dynamic implicit representation is a simplified approach to model condensation–evaporation with a low number of layers and short CPU (central processing unit) time, it shows good agreements with an explicit representation of condensation–evaporation (no significant differences after a few hours of condensation).

The influence of differential evaporation on the structure of a three-component biofuel spray

A high-pressure spray injected under gasoline engine conditions in a constant volume chamber is studied in detail using a three-dimensional computational fluid dynamics approach. Both single-component and ternary mixture (n-alkane and alcohols) spray results are compared with the experimental data from shadowgraphy, Schlieren imaging and phase-Doppler anemometry. Activity coefficient models are used to cover non-ideal thermodynamic effects occurring when mixtures of structurally dissimilar components such as alcohols and n-alkanes are considered. Here, the non-random, two-liquid and universal quasi-chemical functional group activity coefficients methods are applied. A ternary mixture composed of ethanol, n-butanol and n-hexane representing the research octane number (RON 95) of gasoline is considered and investigated in detail. To illustrate the non-ideal mixture effects, first the binary mixtures ethanol/n-butanol, n-butanol/n-hexane and ethanol/n-hexane are studied as subsets of the ternary mixture using a zero-dimensional single-droplet evaporation solver. Introducing a differential evaporation factor for multicomponent mixtures, the mixture segregation is characterized. Additionally, a separation factor indicating which component depletes first (volatility) is presented for both binary and ternary mixtures. The zero-dimensional results are then correlated with the three-dimensional computational fluid dynamics simulation results. Looking at the vapor–liquid equilibria of the different binary mixtures, the non-ideal effects are identified. The evaporation behavior of the binary mixtures is compared with the ternary mixtures in terms of droplet lifetimes, temperature and mixture decomposition, where the latter is characterized with the differential evaporation factor and separation factor. These results are afterwards compared with the three-dimensional computational fluid dynamics simulations, which are validated against the experimental data for single-component sprays regarding the liquid and vapor penetration depths. Finally, in the ternary mixture, n-butanol is replaced with iso-octane, the most widely used gasoline surrogate, to illustrate the differential evaporation behavior for a mixture with a higher alkane content than the ternary mixture used for the experiments. Strong non-ideal effects causing significant changes in the vapor composition are presented, as well as changes in the characterization factors, differential evaporation factor and the separation factor, respectively. These results are compared with the single-droplet simulations.

Rapid Solvent Screening Using Thermodynamic Models for Recovery of 2,3-Butanediol from Fermentation by Liquid–Liquid Extraction

Different classes of solvents were explored for liquid–liquid extraction (solvent extraction) of 2,3-butanediol (BDO) from aqueous solutions. Initially, the activity coefficients (γ∞) of BDO in various solvents were predicted using thermodynamic models, namely conductor-like-screening model-real solvents (COSMO-RS) and universal functional group activity coefficient model (UNIFAC-LL). These models were validated by comparing the distribution coefficients (Kd) predicted from modeling with experimental data for the solvents. Lower chain alcohols and derivatives of phenol showed highest Kd. 1-butanol, 2-sec-butylphenol (SBP) and cyclohexanol showed experimental Kd of 1.6, 1.2 and 0.9, respectively in aqueous fermented BDO broth. The UNIFAC-LL and COSMO-RS based predictions provided qualitative trend for the ranking of solvents, in reasonable agreement with the experimental data. In terms of numerical ability, UNIFAC-LL model performance is better compared to COSMO-RS. However, this work shows that the incorporation of newly improvised UNIFAC parameters in the UNIFAC-LL calculations provides a very satisfactory result, much closer to the experimental values. Therefore, newly parametrized UNIFAC-LL could be used for further studies on process modeling, design, and scale up of BDO extraction from aqueous solution.

Solid–Liquid Equilibrium of Binary Mixtures Containing Fatty Acids and Triacylglycerols

Solid–liquid phase diagrams of the following systems were measured using differential scanning calorimetry (DSC): tristearin (2,3-di(octadecanoyloxy)propyl octadecanoate) + tripalmitin (2,3-di(hexadecanoyloxy)propyl hexadecanoate), tristearin (2,3-di(octadecanoyloxy)propyl octadecanoate) + palmitic acid (n-hexadecanoic acid), tristearin (2,3-di(octadecanoyloxy)propyl octadecanoate) + linoleic acid (cis-9,cis-12-octadecadienoic acid), tripalmitin (2,3-di(hexadecanoyloxy)propyl hexadecanoate) + triolein (2,3-bis[[(Z)-octadec-9-enoyl]oxy]propyl (Z)-octadec-9-enoate), and tripalmitin (2,3-di(hexadecanoyloxy)propyl hexadecanoate) + commercial oleic acid (commercial (Z)-octadec-9-enoic acid). The eutectic point was observed for two systems, tristearin with tripalmitin or with palmitic acid. Polarized optical microscopy was employed to investigate the solid phase of the systems and confirmed the occurrence of a solid solution at the extreme of the phase diagram rich in the component with a higher melting temperature. Margules-2-suffix, Margules-3-suffix, nonrandom two-liquid (NRTL), and universal quasichemical functional group activity coefficient (UNIFAC) models were employed to describe the liquidus line of the studied systems, except for the system formed by tripalmitin (2,3-di(hexadecanoyloxy)propyl hexadecanoate) + commercial oleic acid (commercial (Z)-octadec-9-enoic acid) which is a pseudobinary system that was well-described by the UNIFAC model. The best results for the other systems were obtained when employing the Margules-3-suffix and NRTL models.

Solid−Liquid Equilibrium of Saturated Fatty Acids + Triacylglycerols

Phase diagrams of tricaprylin (1,3-di(octanoyloxy)propan-2-yl octanoate) + myristic acid (tetradecanoic acid), commercial triolein + palmitic acid (hexadecanoic acid), and trilinolenin (propane-1,2,3-triyl tris[(9Z,12Z,15Z)-octadeca-9,12,15-trienoate]) + stearic acid (octadecanoic acid) were obtained by differential scanning calorimetry (DSC). The occurrence of an eutectic point very close to the pure triacylglycerol can be assumed in all of the three investigated systems. The liquid phase was modeled using Margules two-suffix, Margules three-suffix, nonrandom two-liquid (NRTL), and universal quasichemical functional group activity coefficient (UNIFAC) Dortmund models. The best modeling results were obtained using the NRTL model. The UNIFAC Dortmund model describes the multicomponent system containing commercial triolein + palmitic acid well.

Phase Equilibria for Liquid Mixtures of (an Alkane + Toluene + Dimethyl Phthalate)

This study aims to investigate the efficiency of dimethyl phthalate (DMP), having low water solubility, low density, and a high boiling point compared to alkanes, as a solvent to extract toluene from its multicomponent hydrocarbon mixtures. Liquid−liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {heptane or hexane or cyclohexane (1) + toluene (2) + DMP (3)} at T = 298.15 K and 101.3 kPa. The reliability of the experimental tie-line data was verified by using the Othmer−Tobias correlation. Distribution coefficients and separation factors were evaluated for the immiscibility region. The experimental tie-line data were correlated by the universal quasichemical activity coefficient (UNIQUAC) equation and also predicted with the universal functional group activity coefficient (UNIFAC) model. The experimental data were compared with the calculated results.

Simple Approach for Quantifying the Thermodynamic Potential of Polymer–Polymer Adhesion

ABSTRACT The free energies of mixing a series of water-soluble polymers with cellulose were calculated using the UNIFAC (universal functional group activity coefficients) algorithm, and the results were correlated with measurements of polymer/cellulose adhesion. The more negative the minimum free energy of mixing, the greater the measured adhesion. Adhesion was quantified by single-lap shear test in which regenerated cellulose films were laminated with aqueous polymer. The results are relevant to the use of adsorbed water-borne polymers to strengthen cellulose fiber–fiber bonds in paper. The calculations did not anticipate the exceptional strength-enhancing properties of carboxymethyl cellulose, nor did they predict molecular-weight effects. Nevertheless, the approach may have utility as a general tool to relate polymer chemistry to adhesion performance.