Volumetric and viscosity studies of interactions between sodium phosphate salts and poly(propylene glycol) 400 in aqueous solutions at different temperatures

Density and sound velocity at the 288.15–313.15 K and viscosity at the 298.15–313.15 K temperature range at 5 K intervals for polypropylene glycol (PPG) in aqueous solutions of sodium di-hydrogen phosphate, di-sodium hydrogen phosphate and tri-sodium phosphate with salt mass fractions 0.00, 0.010 and 0.020 are reported at atmospheric pressure. From the experimental density and sound velocity data, the apparent specific volume, excess specific volume, isentropic compressibility and isentropic compressibility deviation values have been determined. The infinite dilution apparent specific volume and isentropic compressibility values of PPG have been obtained and from which the infinite dilution apparent specific volumes of transfer of PPG from water to aqueous sodium phosphate solutions have been obtained for the investigated salt concentrations and temperatures. The excess specific volume, isentropic compressibility and viscosity deviation are negative and decrease in magnitude as temperature, concentration of sodium phosphate and charge on the anion of electrolyte increases.     

Effect of sodium phosphate salts on the thermodynamic properties of aqueous solutions of poly(ethylene oxide) 6000 at different temperatures

Precise density, sound velocity, water activity, and phase diagram measurements have been carried out on polyethylene oxide (PEO) in aqueous solutions of sodium di-hydrogen phosphate, di-sodium hydrogen phosphate, and tri-sodium phosphate over a range of temperatures at atmospheric pressure. The experimental density and sound velocity data are used to calculate the apparent specific volume and isentropic compressibility as a function of temperature and concentration. It was found that both of the apparent specific volume and isentropic compressibility of PEO in aqueous solutions increase by increasing temperature and charge on the anion of electrolytes. The results show that the slope of constant water activity lines increased with increasing the temperature and charge on the anion of electrolytes and the vapour pressure depression for an aqueous (PEO + sodium phosphate) system is more than the sum of those for the corresponding binary solutions. Furthermore, the effect of temperature and type of anion of salt on the salting-out effect of polyethylene oxide by sodium phosphate salts has been studied.     

Thermodynamics of aqueous solutions of poly ethylene glycol di-methyl ethers in the presence or absence of ammonium phosphate salts

Precise measurements of density and sound velocity at different temperatures ranging from 283.15 to 308.15 K for solutions of PEGDME250, PEGDME500 and PEGDME2000 in water and of PEGDME500 in aqueous solutions of 0.500 mol kg⁻¹ ammonium di-hydrogen phosphate ((NH₄)H₂PO₄) and di-ammonium hydrogen phosphate ((NH₄)₂HPO₄), binodal curves at temperature ranges 293.15-318.15 K for the aqueous PEGDME500 + (NH₄)₂HPO₄, PEGDME500 + (NH₄)₃PO₄, PEGDME2000 + (NH₄)H₂PO₄, PEGDME2000 + (NH₄)₂HPO₄, PEGDME2000 + (NH₄)₃PO₄ and PPG400 + (NH₄)₂HPO₄ two-phase systems, and liquid-liquid equilibrium data at temperature ranges 298.15-318.15 K for the aqueous PEGDME500 + (NH₄)₂HPO₄ and PEGDME2000 + (NH₄)₂HPO₄ two-phase systems have been taken. From the experimental density and sound velocity data, the apparent specific volume, excess specific volume, isentropic compressibility and isentropic compressibility deviation values have been determined and the effect of temperature, charge on the anion of electrolytes and molar mass of PEGDME on the volumetric and compressibility properties of the investigated polymer solutions as well as on the salting-out effect of PEGDMEs produced by ammonium phosphate salts has been studied.     

Quaternary (liquid + liquid) equilibria of aqueous two-phase poly (ethylene glycol), poly (DMAM–TBAM), and KH2PO4: Experimental and generalized Flory–Huggins theory

Quaternary (liquid + liquid) equilibrium (LLE) data of the aqueous two-phase poly (ethylene glycol), poly (N,N-dimethylacrylamide-t-butylacrylamide) with abbreviation name poly (DMAM–TBAM) as a hydrophobic association water-soluble copolymer and KH₂PO₄ has been determined experimentally at T = 338.15 K. Furthermore, the generalized Flory–Huggins theory with two electrostatic terms (the Debye–Hückel and Pitzer–Debye–Hückel) was used for correlation of the phase behavior of the quaternary system and the interaction parameters between all species were calculated.It was found that addition of poly (DMAM–TBAM) copolymer as well as changing the temperature can shift the binodal curves of aqueous two-phase systems containing polyethylene glycol (PEG) and salt. Also, the phase behavior of the DMAM–TBAM copolymer with some salts containing sodium chloride, ammonium hydrogen phosphate, potassium hydrogen phosphate, and sodium carbonate were studied experimentally at T = 338.15 K and the effect of the salt type on the their binodal curves was determined.     

Measurement and correlation of phase equilibria in aqueous two-phase systems containing polyvinylpyrrolidone and di-potassium tartrate or di-potassium oxalate at different temperatures

Experimental (liquid + liquid) equilibrium (LLE) measurements and the phase diagram have been determined for aqueous two-phase systems containing polyvinylpyrrolidone (PVP) and di-potassium oxalate or di-potassium tartrate at T = (298.15, 308.15, and 318.15) K. Also, the effects of temperature on the binodal curve and tie-lines have been studied. The Merchuk equation was used to correlate the binodal curves of these systems. Furthermore, several suitable equations were used to fit the tie-line data points. The results show that at each temperature, the agreement between the correlated and the experimental values is good with all of these equations. Also, the effects of the type of salt on LLE are discussed.     

(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.     

Effect of temperature on the phase equilibrium of aqueous two-phase systems containing polyvinylpyrrolidone and disodium hydrogen phosphate or trisodium phosphate

Phase diagrams and liquid–liquid equilibrium (LLE) data of the aqueous polyvinylpyrrolidone–disodium hydrogen phosphate and aqueous polyvinylpyrrolidone–trisodium phosphate systems have been determined experimentally at 298.15, 308.15, 318.15 and 328.15 K. The effect of temperature and the type of salt on the binodal and tie-lines has been studied. It was found that, for the studied systems in the polyvinylpyrrolidone (PVP)-rich region, an increase in temperature caused the expansion of one-phase area; while, for the salt-rich region, expansion of the two-phase area was observed with increase in the temperature. It was also observed that the slope of all equilibrium tie-lines increased with increasing temperature. Furthermore, it was found that, as temperature is increased, these aqueous two-phase systems exhibit a phase inversion. Specifically, the PVP-rich phase – which at low temperatures is the less dense top phase – becomes the lower phase at elevated temperatures. Finally, an extended Flory–Huggins theory proposed in our previous paper has been used for correlation of LLE data.     

Effect of temperature on the (liquid + liquid) equilibrium for aqueous solution of nonionic surfactant and salt: Experimental and modeling

The effect of temperature on the (liquid + liquid) equilibrium of the aqueous solution of surfactant polyoxyethylene cetylether (with abbreviation name Brij 58) and diammonium hydrogen phosphate has been investigated at T = (303.15, 313.15, 323.15, and 333.15) K. The Flory–Huggins equation with two electrostatic terms (Debye–Huckle and Pitzer–Debye–Huckle equations) was used to correlate the phase behavior of this system. Good agreement has been found between experimental and calculated data from both models. The results indicated that the enlargement of the two-phase region upon increasing the temperature. Additionally temperature dependency of the parameters of the Flory–Huggins model has been calculated.     

Effects of external electromagnetic field on binodal curve of (water + propionic acid + dichloromethane) ternary system

The effects of an external electromagnetic field on the binodal curve of the (water + propionic acid + dichloromethane) ternary system was investigated at 91.3 kPa and T = (294.15 and 284.15) K. The experimental binodal curve values for the ternary system were obtained by the cloud point method using a new setup with a flat capacitor. The effects of variation of frequencies and amplitude of voltages of the applied external electromagnetic field on the binodal curve results have been evaluated. The results obtained indicate that the heterogeneous two-phase area increases with increasing frequency of the applied external electromagnetic field. At constant frequency, a similar effect has been found by increasing the amplitude of the voltage of the applied external electromagnetic field. The comparison between the results obtained for this work with those reported in previous work indicates that the treatment efficiency in liquid–liquid extraction process of (water + propionic acid + dichloromethane) ternary system can be governed by the applied external electromagnetic field.     

(Surfactant + polymer) interaction parameter studied by (liquid + liquid) equilibrium data of quaternary aqueous solution containing surfactant,polymer, and salt

(Liquid + liquid) equilibrium (LLE) data of quaternary aqueous system containing polyoxyethylene (20) cetyl ether (with abbreviation name Brij 58, non-ionic surfactant), diammonium hydrogen phosphate, and poly ethylene glycol (PEG) with three molar masses {M_W = (1000, 6000, and 35,000) g · mol^?1} have been determined experimentally at T = 313.15 K.Furthermore, the Flory–Huggins theory with two electrostatic terms (Debye–Hückel and Pitzer–Debye–Hückel equations) have been used to calculate the phase behavior of the quaternary systems and (surfactant + polymer) interaction parameter as well as interaction parameters between other species. Temperature dependency of the parameters of the Flory–Huggins theory has been obtained.Also an effort have been done to show that addition of PEG as well as increasing the temperature can shift the binodal curves of the ternary aqueous system containing surfactant and salt to lower mole fraction of salt. Also the effect of polymer molar mass on the binodal diagram displacement has been discussed.     

A thermodynamic study on solubility and liquid−liquid phase behaviour for 2,2,2-trifluoroethanol + cyclohexane + 1-butanol at three temperatures and pressure 101.3 kPa

This study demonstrates the course of solubility and (liquid + liquid) equilibrium (LLE) for the system (cyclohexane + 1-butanol + 2,2,2-trifluoroethanol) at temperatures of (288.15, 298.15, and 308.15) K and pressure 101.3 kPa. The titration method was used to assess solubility (binodal) curves, while a direct analytical method to acquire tie lines.The consistency of the binodal curves and phase diagrams data were well calculated by Hand and Othmer–Tobias empirical equations. The NRTL and UNIQUAC thermodynamic models gave accurate tie-line values for the systems. Plait-point, distribution coefficient, solvent selectivity, and NRTL and UNIQUAC binary interaction parameters were obtained.The immiscibility region of the system decreases significantly with increasing temperature. The results present an overview of the high efficiency of liquid extraction using 2,2,2-trifluoroethanol as solvent to yield pure cyclohexane from its 1-butanol azeotrope mixture at ambient temperatures.     

Quaternary (liquid + liquid) equilibria of aqueous two-phase polyethylene glycol,poly-N-vinylcaprolactam,and KH2PO4: Experimental and the generalized Flory–Huggins theory

A quaternary (liquid + liquid) equilibrium study was performed to focus attention on the interaction parameters between poly-N-vinylcaprolactam (PVCL) and poly-ethylene glycol (PEG) as well as between other species. At first, the new experimental data of (liquid + liquid) equilibria for aqueous two-phase systems containing PEG, KH₂PO₄, and PVCL at T = 303.15 K have been determined. Then the Flory–Huggins theory with two electrostatic terms (the Debye–Huckel and the Pitzer–Debye–Huckel equations) has been generalized to correlate the phase behavior of the quaternary system. Good agreement has been found between experimental and calculated data from both models especially from the Pitzer–Debye–Huckel equation.Also an effort was done to compare the effect of temperature as well as addition of PVCL on the binodal curves of PEG, KH₂PO₄, and water. The effect of the type of salt on the binodals has been also studied, and the salting out power of the salts has been determined.     

(Liquid + liquid) equilibria for (acetate-based ionic liquids + inorganic salts) aqueous two-phase systems

In the present work, (liquid + liquid) equilibrium data have been determined experimentally for aqueous two-phase systems formed by the imidazolium ionic liquids of [C_nmim][CH₃COO] (n = 4, 6, 8) and inorganic salts of K₃PO₄, K₂HPO₄, and K₂CO₃ at T = 298.15 K. Combined with available data in the literature, the effect of alkyl chain length of cations, type of anions of the ionic liquids, and nature of the inorganic salts were examined on the binodal curves of the systems. Then the binodal curves were fitted to a four-parameter empirical equation, and the tie-lines were described by the Othmer–Tobias and Bancroft equations. In addition, the extraction capacity of the {[C_nmim][CH₃COO] (n = 4, 6, 8) + K₃PO₄} aqueous two-phase systems was evaluated through their application to the extraction of l-tryptophan. The high extraction efficiency suggests that these aqueous two-phase systems are feasible to be used in the extraction and separation process.     

Thermophysical properties of biodiesel and related systems: (Liquid + liquid) equilibrium data for castor oil biodiesel

This work reports new liquid–liquid solubility values (binodal curves) as well as (liquid + liquid) equilibrium data for, ternary and quaternary systems containing fatty acid methyl esters (FAME) and fatty acid ethyl esters (FAEE) from castor oil, water, glycerol, methanol and anhydrous ethanol at T = (303.15, 318.15, and 333.15) K. Solubility curves (binodal) were also obtained by the cloud-point method for binary systems containing FAME, FAEE, water, or glycerol. All results obtained can be considered of good quality. The experimental values were correlated using the UNIQUAC model, whose results presented good performance and satisfactory fitting of equilibrium values.     

Cosolutes effects on aqueous two-phase systems equilibrium formation studied by physical approaches

The effect of urea and sodium salts of monovalent halides on the aqueous polyethyleneglycol solution and binodal diagrams of polyethyleneglycol–potassium phosphate (polyethyleneglycol of molecular mass 1500, 4000, 6000 and 8000) were studied using different physical approaches. The effect of these solutes on the binodal diagram for polyethyleneglycol–potassium phosphate was also investigated. The cosolutes affected in a significant manner the water structured around the ethylene chain of polyethyleneglycol inducing a lost of this. The equilibrium curves for the aqueous two-phase systems were fitting very well by a sigmoidal function with two parameters, which are closely related with the cosolute structure making or breaking capacity on the water ordered.     

Binodal curve measurements for (water + propionic acid + dichloromethane) ternary system by cloud point method

The binodal (solubility) curves and tie line data for ternary systems of (water + propionic acid + dichloromethane) at 91.3 kPa and T = (277.15, 284.15, and 294.15) K are reported. The binodal curve results were determined by cloud point measurements method. A simple titration method has been used for determining of the concentration of propionic acid in the both liquid phases at equilibrium. The results obtained were successfully correlated with the UNIQUAC activity coefficient model. The deviations between experimental and calculated compositions in both phases for the ternary system using this model are reported. The partition coefficients of propionic acid and the selectivity factor of dichloromethane for extracting of propionic acid from water were calculated and are reported. The phase diagrams for the ternary system studied including both the experimental and correlated tie lines are presented.     

Phase compositions,viscosities and densities of systems PPG425 + Na2SO4+H2O and PPG425 + (NH4)2SO4 + H2O at 298.15 K

Phase diagrams of PPG425+Na₂SO₄+H₂O and PPG425+(NH₄)₂SO₄+H₂O systems at 298.15 K were measured. The densities and viscosities of two-phase systems were also measured. The improved regular solution theory was used to correlate the equilibrium data. In this theory a mixing entropy term and the Fowler-Guggenheim long-range electrostatic term has been used.     

Liquid–liquid equilibria for pseudo-ternary systems: (Sulfolane + 2-ethoxyethanol) + octane + toluene at 293.15 K

Liquid–liquid equilibrium data, both binodal and tie lines are presented for the pseudo-ternary systems: {(sulfolane + 2-ethoxyethano) (1) + octane (2) + toluene (3)} at 293.15 K. The experimental liquid–liquid equilibrium data have been correlated using NRTL and UNIQUAC models, and the binary interaction parameters of these components have been presented. The correlated tie lines have been compared with the experimental data. The comparisons indicate that both NRTL and UNIQUAC models satisfactorily correlated the equilibrium compositions. The tie-line data of the studied systems also were correlated using the Hand method.     

Liquid–liquid equilibria of the ternary system water + acetic acid + dimethyl succinate

Liquid–liquid equilibrium (LLE) data of water + acetic acid + dimethyl succinate were measured at 298.2, 308.2, and 318.2 K. Complete phase diagrams were obtained by determining binodal curves and tie lines. The reliability of the experimental tie line data was confirmed by using the Othmer–Tobias correlation. The UNIFAC and modified UNIFAC model were used to predict the phase equilibrium data in the ternary system. Distribution coefficients and separation factors were evaluated for the immiscibility region.     

The effect of temperature and molar mass on the (liquid + liquid) equilibria of (poly ethylene glycol dimethyl ether + di-sodium hydrogen citrate + water) systems: Experimental and correlation

The (liquid + liquid) equilibrium for the {polyethylene glycol dimethyl ether 2000 (PEGDME₂₀₀₀) + di-sodium hydrogen citrate + H₂O} system was studied at T = (298.15, 308.15 and 318.15) K and atmospheric pressure (≈85 kPa). The free energies, enthalpies and entropies of cloud points were calculated in order to investigate the driving force formation of this two-phase system. To investigate the effect of molar mass of the polymer on the binodals and tie-lines, similar measurements were also made at T = 298.15 K on this two-phase system consisting of the PEGDME with molar masses of 500 and 250 g ⋅ mol⁻¹. The effective excluded volume model was used for representation of the phase-forming ability in PEGDME systems. An empirical and the Merchuck equations with the temperature dependency were used to correlate the binodal curves. The Othmer–Tobias and Bancraft and Setschenow equations, the osmotic virial and the extended NRTL models were used to fit the tie-line data.