Experimental measurement and modelling of KBr solubility in water,methanol, ethanol,and its binary mixed solvents at different temperatures

A simple and accurate apparatus has been designed to measure the solubilities of potassium bromide by an analytical method. Salt solubility data have been measured in water, methanol, ethanol, (water  +  methanol), (water  +  ethanol), and (methanol  +  ethanol) solvents in the temperature range between 298.15 K and 353.15 K.A new formulation is presented for the calculation of salt solubility in pure and mixed solvents as a function of the temperature and solvent composition. This formulation is based on the symmetric convention for the normalization of the activity coefficients for all species in solution, and makes possible direct access to the solubility product of the salt in terms of its thermodynamic properties. The new solubility data measured in this work, as well as experimental information from the open literature, are used to estimate the interaction parameters of the two models proposed here. One model combines the original Universal Quasi Chemical (UNIQUAC) equation with a Pitzer–Debye–Hückel expression to take into account the long-range interaction forces; the other model only considers the short-range forces through the UNIQUAC equation with linear temperature dependent salt/solvent interaction parameters. Both models correlate satisfactorily the solubility data, although temperature and electrostatic effects are both very important in this type of equilibrium. Finally, some conclusions are drawn concerning the models versatility to represent other type of equilibrium data and prediction capabilities.     

Solubility measurement and modelling of 1,8-dinitronaphthalene in nine organic solvents from T = (273.15 to 308.15) K and mixing properties of solutions

The solubility of 1,8-dinitronaphthalene in acetonitrile, methanol, ethanol, trichloromethane, isopropanol, acetone, toluene, ethyl acetate and butyl alcohol were obtained experimentally at temperatures ranging from (273.15 to 308.15) K under 0.1 MPa by using a gravimetric method. The solubility of 1,8-dinitronaphthalene in those solvents increases with an increase in temperature. The solubility values decrease according to the following order: acetone > (acetonitrile, ethyl acetate) > trichloromethane > toluene > methanol > ethanol > isopropanol > butyl alcohol. Three models, the modified Apelblat equation, Wilson and NRTL were used to correlate the solubility of 1,8-dinitronaphthalene in the solvents studied. The calculated solubility by the modified Apelblat equation provides better agreement than those evaluated by the other two models. The regressed results via the three models are all acceptable for the solubility of 1,8-dinitronaphthalene in the selected solvents. Furthermore, the mixing Gibbs energy, mixing enthalpy, and mixing entropy for per 1 mol of mixture of 1,8-dinitronaphthalene and solvents were calculated based on the Wilson model. The dissolution process of 1,8-dinitronaphthalene in the selected solvents is spontaneous and exothermic.     

Solubility and pKa of select pharmaceuticals in water,ethanol, and 1-octanol

Solubilities of six pharmaceuticals, namely nadolol, atenolol, bifonazole, nimesulide, estrone, mefenamic acid at constant pH, were measured over the range of temperature from (240 to 340) K in three important for drug solvents: water, ethanol, and 1-octanol using the dynamic method and spectroscopic UV–Vis method. Dissociation constants and corresponding pK_a values of the drugs were obtained with the Bates–Schwarzenbach method using UV–Vis Perkin–Elmer Lambda 35 Spectrophotometer at temperature 298.15 K in the buffer solutions. Our experimental pK_a values for nadolol, bifonazole, nimesulide, and mefenamic acid are 9.3, 5.85, 7.34, and 3.88, respectively. The basic thermal properties of pure drugs i.e. fusion and glass-transition temperatures, as well as the enthalpy of fusion and the molar heat capacity at the glass-transition (at constant pressure) have been measured using the differential scanning microcalorimetry technique (DSC). Molar volumes have been calculated with the Barton group contribution method. The experimental solubility results have been correlated by means of three commonly known G^E equations: the Wilson, NRTL, and UNIQUAC with the assumption that the systems studied here are simple eutectic mixtures. The activity coefficients of pharmaceuticals in saturated solutions in each correlated binary mixture were calculated from the experimental results. Prediction of solubility in water at T = 298.15 K was made by the group contribution method.     

Experimental measurement and modelling of solubility of inosine-5′-monophosphate disodium in pure and mixed solvents

The solubility of biological chemicals in solvents provide important fundamental data and is generally considered as an essential factor in the design of crystallization processes. The equilibrium solubility data of inosine-5′-monophosphate disodium (5′-IMPNa₂) in water, methanol, ethanol, acetone, as well as in the solvent mixtures (methanol + water, ethanol + water, acetone + water), were measured by an isothermal method at temperatures ranging from (293.15 to 313.15) K. The measured data in pure and mixed solvents were then modelled using the modified Apelblat equation, van’t Hoff equation, λh equation, ideal model and the Wilson model. The modified Apelblat equation showed the best modelling results, and it was therefore used to predict the mixing Gibbs free energies, enthalpies, and entropies of 5′-IMPNa₂in pure and binary solvents. The positive values of the calculated partial molar Gibbs free energies indicated the variations in the solubility trends of 5′-IMPNa₂. Water and ethanol (in the binary mixture with water) were found to be the most effective solvent and anti-solvent, respectively.     

Isobaric (vapour + liquid) equilibria for the (1-pentanol + propionic acid) binary mixture at (53.3 and 91.3) kPa

Isobaric (vapour + liquid) equilibrium measurements have been reported for the binary mixture of (1-pentanol + propionic acid) at (53.3 and 91.3) kPa. Liquid phase activity coefficients were calculated from the equilibrium data. The thermodynamic consistency of the experimental results was checked using the area test and direct test methods. According to these criteria, the measured (vapour + liquid) equilibrium results were found to be consistent thermodynamically. The obtained results showed a maximum boiling temperature azeotrope at both pressures studied. The measured equilibrium results were satisfactorily correlated by the models of Wilson, UNIQUAC, and NRTL activity coefficients. The results obtained indicate that the performance of the NRTL model is superior to the Wilson and UNIQUAC models for correlating the measured isobaric (vapour + liquid) equilibrium data.     

Mutual solubility measurements and correlations of imidazolium-based ionic liquid mixtures with alcohols

The mutual solubility of ionic liquids (ILs), 1-butyl-3-ethylimidazolium tetrafluoroborate, 1-butyl-3-propylimidazolium tetrafluoroborate, and 1,3-dibutylimidazolium tetrafluoroborate with alcohols, 1-propanol, 1-butanol, 1-pentanol, and 1-hexanol were measured at atmospheric pressure. Upper critical solution temperatures (UCSTs) were estimated from experimental results using a polynomial equation. The UCSTs increased as increasing the chain length of alcohol. On other hand, the decreasing UCSTs occurred when the alkyl chain length on the cation of ionic liquids increased. The (liquid + liquid) equilibrium data were correlated by the original UNIQUAC, extended UNIQUAC, and modified UNIQUAC models. The temperature dependence of the solubility of ILs in alcohols and alcohols in ILs is represented successfully using the UNIQUAC, extended UNIQUAC, and modified UNIQUAC models with a quadratic function of temperature for binary energy parameters.     

(Liquid + liquid) equilibria in (water + ethanol + 2-ethyl-1-hexanol) at T=(298.2, 303.2, 308.2, and 313.2) K

(Liquid + liquid) equilibrium data for (water + ethanol + 2-ethyl-1-hexanol) were measured at atmospheric pressure in the temperature range (298.2 to 313.2) K. A type 1 (liquid + liquid) phase diagram was obtained for this ternary system. The experimental tie-line data for this system were correlated with the UNIQUAC solution model. The values of the interaction parameters between each pair of components in the system were obtained for the UNIQUAC model with the experimental results. The root mean square deviation between the observed and calculated mole per cent was 1.70%. The mutual solubility of 2-ethyl-1-hexanol and water was also investigated by the addition of ethanol at different temperatures.     

(Solid + liquid) phase equilibria of binary mixtures containing N-methyl-2-pyrrolidinone and ethers at atmospheric pressure

Solid–liquid equilibria (SLE), have been measured from 270 K to the boiling temperature of the solvent for 10 binary mixtures of N-methyl-2-pyrrolidinone, with ethers (dipropyl ether, dibutyl ether, dipentyl ether, methyl 1,1-dimethylethyl ether, methyl 1,1-dimethylpropyl ether, ethyl 1,1-dimethylpropyl ether, 1,4-dioxane, tetrahydrofuran, tetrahydropyran, 18-crown-6) using a dynamic method. The solubility of N-methyl-2-pyrrolidinone in ethers is lower than in alcohols and generally decreases with an increase of the number of carbon atoms of ether chain. The highest intermolecular solute–solvent interaction is observed for the cyclic ethers and for methyl 1,1-dimethylethyl ether.Experimental solubility results are compared with values calculated by means of the Wilson, UNIQUAC ASM and two NRTL equations utilizing parameters derived from SLE results. The existence of a solid–solid first-order phase transition in 18-crown-6 ether has been taken into consideration in the calculations. The correlation of the solubility data has been obtained with the average root-mean-square deviation of temperature σ_T = 0.9 K with UNIQUAC ASM and two NRTL equations and 0.6 K with the Wilson equation.     

Solubility of tridecanedioic acid in pure solvent systems: An experimental and computational study

Solubility has been extensively investigated by the phase equilibria approach at the mesoscale level, but its origin on the molecular and electronic levels is poorly understood. This study explored the solubility behaviour of crystalline solid in selected pure solvents with various functional groups by using both phase equilibria and molecular modelling methods. The model compound tridecanedioic acid (TDDA) solubility in methanol, ethanol, acetic acid, acetone, and ethyl acetate was determined from T = (283.15 to 323.15) K by a static method. It was found that almost all solutions studied exhibit non-ideal behaviour and deviate positively from Raoult’s law indicating the important role of homo-molecules interactions. Thermodynamic analyses of solution suggest that both enthalpy and entropy of solution govern the dissolution process. Computational studies on solubility behaviour were performed by using both density functional theory (DFT) calculations and molecular dynamic (MD) simulations. The results conclude that the (solute + solvent) interaction is not the only factor determining solubility, and (solvent + solvent) interaction also plays an important role. The simulated results are found to be qualitatively consistent with experimental values. Finally, solubility values were correlated by the empirically modified Apelblat equation and two local composition models of Wilson and NRTL.     

Thermodynamics of 4’-bromomethyl-2-cyanobiphenyl in different solvents

The melting properties and the heat capacity of the solid state and the melt state 4’-bromomethyl-2-cyanobiphenyl (OTBNBr) were determined. The enthalpy, entropy and Gibbs free energy of fusion were also calculated. The solubility of OTBNBr in eight organic solvents was experimentally measured at temperatures from (283.15 to 323.15) K by using a static method. The reasons for the differences of the solubility of OTBNBr in various solvents are discussed by using the intermolecular interaction. Furthermore, the experimental solubility values were well correlated by the modified Apelblat equation, the λh equation, the Wilson model and the van’t Hoff equation. Finally, the temperature dependence of the activity coefficient and the van’t Hoff enthalpy in the tested solutions was investigated and is discussed.     

(Solid + liquid) phase equilibria of binary mixtures containing N-methyl-2-pyrrolidinone and alcohol at atmospheric pressure

The (solid + liquid) equilibria of {N-methyl-2-pyrrolidinone + 1-propanol, or 2-propanol, or 1-butanol, or 2-methyl-1-propanol, or 2-methyl-2-propanol, or 1-pentanol} has been measured by a dynamic method. The experimental results have been correlated using the Wilson, UNIQUAC ASM and two modified NRTL equations. The root-mean-square deviations of the solubility temperatures for all the calculated values vary from (0.5 to 2.1) K and depend on the particular equation used. The specific interaction between the carbonyl group of the NMP molecule and the alcohol has been discussed.     

Isothermal (vapour + liquid) equilibria for the binary (cyclopentanone or cyclohexanone with 1,1,2,2-tetrachloroethane) systems at temperatures of (343.15, 353.15, and 363.15) K

The vapour pressure of pure components and isothermal (vapour + liquid) equilibrium data at temperatures of (343.15, 353.15, and 363.15) K for binary mixtures containing (cyclopentanone or cyclohexanone with 1,1,2,2-tetrachloroethane) are reported. Use has been made of an ebulliometer which allowed sampling from both phases in equilibrium. Both systems exhibit azeotrope with minimum pressure at all three temperatures. The experimental data were correlated using the Redlich–Kister, Wilson, NRTL and UNIQUAC models by means of maximum likelihood method. The systems show negative deviations from ideal behaviour.     

Determination and correlation of solubility of tylosin tartrate in alcohol mixtures

Data on (solid + liquid) equilibrium of tylosin tartrate in {methanol + (ethanol, 1-propanol or 2-propanol)} solvents will provide essential support for industrial design and further theoretical studies. In this study, the solubility of tylosin tartrate in alcohol mixtures was measured over temperature range from (278.15 to 323.15) K under atmospheric pressure by a gravimetric method. From the experimental results, the solubility of tylosin tartrate in selected solvents noted above was found to increase with increasing temperature and mass fraction of methanol. The solubility data were correlated with the modified Apelblat equation, the λh equation and van’t Hoff equation. The results showed that the three equations agreed well with the experimental values, and that the modified Apelblat equation was more accurate than the λh equation and van’t Hoff equation. Further, the standard enthalpy, standard entropy and standard Gibbs free energy of solution of tylosin tartrate in mixed solvents were calculated according to solubility results, model parameters with modified Apelblat equation and van’t Hoff equation.     

Binary and ternary (liquid + liquid) equilibrium for {methylcyclohexane (1) + toluene (2) + 1-hexyl-3-methylimidazolium tetracyanoborate (3)/1-butyl-3-methylimidazolium tetracyanoborate (3)}

This paper focuses on the study of the solubility behaviour of 1-hexyl-3-methylimidazolium tetracyanoborate [HMIM][TCB] and 1-butyl-3-methylimidazolium tetracyanoborate [BMIM][TCB] in combination with methylcyclohexane and toluene as representatives for non-aromatic and aromatic components. Binary and ternary (liquid + liquid) equilibrium data were collected at three different temperatures and at atmospheric pressure (0.1 MPa). The experimental data were well-correlated with the NRTL and UNIQUAC thermodynamic models; however, the UNIQUAC model gave better predictions than the NRTL, with a root mean square error below 0.97%. The non-aromatic/aromatic selectivities of the ionic liquids make them suitable solvents to be used in extractive distillation processes.     

Ternary equilibrium data of mixtures consisting of 2-butanol,water, and heavy alcohols at T = 298.2 K

Experimental solubility curves and tie-line data for the (water + 2-butanol + organic solvents) systems were obtained at T = 298.2 K and atmospheric pressure. The organic solvents were four heavy alcohols, i.e. 1-hexanol, 1-heptanol, 1-octanol, and 1-decanol. The consistency of the experimental tie-line data was determined through the Othmer–Tobias and Bachman equations. Distribution coefficients and separation factors were calculated to evaluate the extracting capability of the solvents. The experimental data were correlated using the NRTL (α = 0.2) and UNIQUAC models, and binary interaction parameters were obtained. The average root mean square deviation values between the experimental and calculated data show the capability of these models, in particular NRTL model, in correlation of the phase behavior of the ternary systems.     

(Liquid + liquid) equilibrium of (NaNO3 + PEG 4000 + H2O) ternary system at different temperatures

Phase diagram and (liquid + liquid) equilibrium (LLE) data for the (NaNO₃ + polyethylene glycol 4000 (PEG 4000) + H₂O) system have been determined experimentally at T = (288.15 and 308.15) K. The effects of temperature on the binodal curves and tie-lines have been studied and it was found that an increasing in temperature caused the expansion of two-phase region. The Chen-NRTL, modified Wilson and UNIQUAC models were used to correlate the experimental tie-line data. The results show that the quality of fitting is better with the UNIQUAC model.     

(Liquid + liquid) phase behavior for systems containing (aromatic + TBA + methylcyclohexane)

The determination region of solubility of TBA (tert-butanol) with representative compounds of the gasoline was investigated experimentally at temperature of 298.2 K. Type 1 (liquid + liquid) phase diagrams were obtained for (methylcyclohexane + TBA + aromatic compounds). These results were correlated simultaneously by the UNIQUAC model. The values of the interaction parameters between each pair of components in the systems were obtained for the UNIQUAC model using the experimental result. The root mean square deviation (RMSD) between the observed and calculated mole percents was 1.88 for (methylcyclohexane + TBA + benzene), 2.45 for (methylcyclohexane + TBA + toluene) and 2.86 for (methylcyclohexane + TBA + ethylbenzene). The mutual solubility of methylcyclohexane and aromatic compounds (e.g., benzene toluene and ethylbenzene (BTE)) was also investigated by the addition of TBA at temperature of 298.2 K.     

(Vapour + liquid) equilibrium of binary mixtures (1,3-dioxolane or 1,4-dioxane + 2-methyl-1-propanol or 2-methyl-2-propanol) at isobaric conditions

Isobaric (vapour + liquid) equilibrium of (1,3-dioxolane or 1,4-dioxane + 2-methyl-1-propanol or 2-methyl-2-propanol) at 40.0 kPa and 101.3 kPa has been studied with a dynamic recirculating still. The experimental VLE data are thermodynamically consistent. From these data, activity coefficients were calculated and correlated with the Margules, van Laar, Wilson, NRTL and UNIQUAC equations. The VLE results have been compared with the predictions by the UNIFAC and ASOG methods.     

Isobaric (vapour + liquid) equilibrium for N-methyl-2-pyrrolidone with branched alcohols

The (vapour + liquid) equilibrium (VLE) and boiling temperature measurements have been determined at 95.3 kPa as a function of composition for the binary liquid mixtures of N-methyl-2-pyrrolidone (NMP) with branched alcohols using a Swietoslawski-ebulliometer. The branched alcohols include 2-propanol, 2-butanol, 2-methyl-l- propanol, 2-methyl-2-propanol, and 3-methyl-l-butanol. The experimental temperature-composition (T–x) results were used to estimate Wilson parameters and then used to calculate the equilibrium vapour compositions and the excess Gibbs free energy at T = 298.15 K. The experimental temperature-composition (T, x) results were correlated with the Wilson, the NRTL and the UNIQUAC models. The experimental results are interpreted in terms of intermolecular interactions between constituent molecules.     

Solubility of hydrogen in toluene for the ternary system H2 + CO2 + toluene from 305 to 343 K and 1.2 to 10.5 MPa

The solubility of hydrogen in toluene in the presence of the compressed CO₂ at the temperatures from 305 to 343 K and the pressures from 1.2 to 10.5 MPa was measured by using a continuous flow technique. The obtained data indicate that more hydrogen could be dissolved in toluene at the pressures higher than a certain value depending on temperature and the molar ratio of H₂ to CO₂ in gas. The Peng–Robinson equation of state associated with the van der Waals mixing rule were found to correlate the VLE data of the ternary system H₂ + CO₂ + toluene satisfactorily. From the volume expansion resulted from the dissolution of CO₂ in toluene calculated by the proposed model, it was found that hydrogen solubility was generally increased with increasing volume expansion. A large volume expansion was required to enhance hydrogen solubility when the mole fraction of hydrogen in gas was low.