Slope Of Tie-line Research Articles

Influence of the temperature and type of macromolecule on phase diagrams of aqueous two-phase systems

Phase diagrams for aqueous two-phase systems formed by L64 + Na2SO3 + H2O, F68 + Na2SO3 + H2O, polyethylene glycol 10,000 g·mol–1 (PEG10k) + Na2SO3 + H2O and PEG 35,000 g·mol–1 (PEG35k) + Na2SO3 + H2O were determined experimentally at temperatures of 278.15, 288.15 and 298.15 K, at 0.09 MPa. The binodal curve is not significantly shifted with varying temperature, indicating a small change on the system enthalpy during the phase separation process, but an increase in the temperature promoted an increase in the slope of tie-line. The effectiveness of macromolecules in promoting phase separation occurs in the following order: PEG35k > PEG10k ≈ F68 > L64. An increase in molar mass requires lower concentrations to induce phase separation, due to the decrease of configurational entropy of the solution. When comparing macromolecules with similar molar masses, PEG10k required slightly lower concentrations than F68 to induce phase segregation. Although PEG10k has a higher molar mass, the structure of F68 contains hydrophobic groups (poly(propylene glycol)) that compensate for its lower molar mass, which generates similar phase segregation induction capabilities. Therefore, new aqueous two-phase systems have been characterized by extending the range of systems available for applications.

Design of novel aqueous two-phase systems to be coupled in biological remediation processes

The ability of a biodegradable Deep Eutectic Solvent (DES) reline to induce phase segregation in aqueous solutions of polymeric non-ionic surfactants (Tween 20 and Tween 80) has been demonstrated as a preliminary step to be employed for assisting a biological degradation process of a model contaminant. The binodal curves for systems composed of (surfactants + reline + Water) have been determined at several temperatures, and the experimental data have been correlated using well-known equations. The equilibrium data have been analysed in the light of the operating temperature and the hydrophobicity of surfactants. Tie-lines of these systems have been determined, together with useful parameters such as tie-line length and tie-line slopes. Othmer-Tobias and Bancroft equations have been applied to provide an adequate description of the equilibrium data. Finally, the application of this new approach for the remediation of aqueous polluted effluent has proven to be highly efficient, with extraction percentages exceeding 99% for two model persistent contaminants (Acid Black 48 and Crystal Violet). Consequently, this ATPS is proposed as an extra-stage to enhance the remediation percentages achieved through biological methods. Furthermore, the process has been simulated using commercial software.

Measurements, correlations and thermodynamic modeling of aqueous two-phase systems of polyvinylpyrrolidone (PVP) + sulfate/citrate salts

Aqueous two-phase systems (ATPS) can be described as an alternative to traditional liquid-liquid extraction systems, typically consisting of a polymer and a salt solution. An alternative polymer called polyvinylpyrrolidone (PVP) has emerged as a viable option for ATPS due to its low cost, stability, and potential. This study aimed to investigate the effect of the molecular weight of poly (vinylpyrrolidone) (PVP) (K17, K25, and K30) and the temperature (298.15, 303.15, and 308.15 K) in the system ATPSs composed of PVPs and sodium sulfate/potassium sulfate/tri sodium citrate. The tie-line data were determined by measuring the density (ρ) and refractive index (nD). Moreover, the phase compositions and plait point are investigated for different PVPs molecular weight, temperature, and salt type. In addition, the effect of these parameters on the binodal curve, tie-line length (TLL), and slope of tie line (STL) are analyzed in detail by comparing them with the literature data. The impact of the parameters on the binodal curves was investigated by utilizing the values of the effective excluded volume parameter (EEV) that were calculated from the LLE data. Furthermore, the binodal curves and the tie-line compositions were well-fitted by using some semi-empirical equations. The phase separation ability is enhanced with temperature and PVPs molecular weight. The modified UNIFAC-NRF is used to correlate the liquid-liquid equilibrium data of the studied systems and the optimized binary group interaction parameters were determined.

Extractive desulfurization of liquid hydrocarbon fuel using ionic liquids: Cationic and anionic selection through Principal Component Analysis and experimental study

Extractive desulfurization using ionic liquids has gained more attraction due to simplicity and easy operating conditions of sulfur compounds removal from liquid hydrocarbon fuels. But the selection of proper cations and anions are still the most challenging parts of all researches. In the present study, a new methodology was developed for screening of cation and anion molecules to obtain maximum sulfur removal efficiency. At first, the best structural descriptors were selected using Genetic algorithm. The different kinds of 1D, 2D and 3D molecular descriptors for a diverse library of cation/anion have been evaluated, including 114 cations and 48 anions. Then, the most proper cations and anions have been selected using Principal Component Analysis (PCA) after evaluating the most accurate structural descriptors for various cations and anions. It was concluded that ionic liquids (ILs) comprise imidazolium and pyridinium cations with hexyl chain, combined with the [N(CN)2] and [Ac] anions, are promising ILs as extraction solvents for extractive desulfurization. To evaluate the obtained results, one of the selected ILs, 1-Hexyl-3-methyl pyridinium dicyanamide ([HMPY][N(CN)2]), has been examined and has been synthesized for the first time as extractant for EDS. The synthesized IL was examined through NMR and FTIR analysis. After that by investigating results and the slope of tie-lines, distribution coefficient, selectivity and the capability of selected IL to sulfur removal of DBT or BT in both phases, it is observed that [HMPY][N(CN)2] is a proper solvent for extraction of DBT or BT from n-heptane.

Thermodynamic insights into phase behavior a new aqueous two-phase system at different temperatures: Experimental equilibria, data correlation and modeling

In the current research, a novel aqueous ternary-two-phase system (ATPS) containing a deep eutectic solvent (DES formed by mixing choline chloride with polyethylene glycol 400) and the non-ionic surfactant Triton X-100 was designed. The phase behavior of this system including phase diagrams (binodal curves) and tie-line compositions was thermodynamically investigated at the temperature range of 298.15 to 316.15 K under atmospheric pressure. This system presented a DES-rich top phase and a surfactant-rich bottom phase. The plait point of binodal diagrams together with the tie-lines length (TLL) and the slope of tie-lines (STL) were determined at each of the operational temperatures. The influence of temperature on the binodal curves and the tie-lines was analyzed from which it was found that an increase in the temperature expands the two-phase region in the binodal curve as well as increases the length of the tie-lines. Moreover, the binodal curves data and the tie-line compositions were successfully correlated using a series of semi-empirical models with satisfactory results. Finally, the molar Gibbs energy, molar enthalpy and molar entropy of the cloud points of binodal curve were calculated and the results showed that the formation of the two-phase system is spontaneous and endothermic as well as the entropy is its driving force.

Temperature, Polymer Molecular Weight, and Salt Effects on Phase Equilibria of PVP + Formate Salts + Water: Experimental Measurements, Correlations, and Thermodynamic Modeling

The phase diagram and liquid–liquid equilibrium data for poly(vinyl pyrrolidone) (PVP) of different molecular weights (10,000, 24,000, or 40,000) + potassium formate (KCHO2) or sodium formate (NaCHO2) aqueous two-phase systems were determined experimentally at different temperatures (298.15, 308.15, and 318.15 K). The phase composition and the tie-line ends were obtained by measuring and correlating the density (ρ) and refractive index (nD) of binary and ternary mixtures within the range of 0–46.6 wt % of PVP and 0–30 wt % of used salts. Furthermore, the binodal data were fitted to both the Pirdashti and Merchuk equations. The cloud point of PVP solutions was determined in the presence of salt at different concentrations. Additionally, the influence of the polymer’s molecular weight and temperature on the binodal curve, tie-line length, and slope of tie-line is discussed and compared with the literature data. Moreover, the impact of the Hofmeister series on the separation factor of formate ion was determined. Finally, the extended NRTL and modified UNIFAC-NRF were used to compute the phase compositions of the studied systems, and the adjusted parameters of the models were reported. Results show that both models provide satisfactory agreement with experimental data.

Phase Equilibria of PEG/Sulfate Salt Aqueous Two-Phase Systems: Effects of pH and Molecular Weight of Polymer

In this study, the liquid-liquid equilibrium (LLE) in the aqueous two-phase system (ATPS) formed by polyethylene glycol (PEG1500 and PEG6000) and magnesium sulfate is investigated. The experimental measurements were performed at temperature of 298.15 K and pH values of 3.60, 5.00, 6.67. Densities and refractive indices of the mixtures were first measured to obtain the compositions from the plotted tie lines. The effects of pH and molecular mass of polymers on the binodal curve, tie lines length (TLL) and slope of tie line (STL) have been examined. It was found the pH values and molecular weight rise the heterogeneous region for each system. The binodal curve was fitted to the Merchuk and the Pirdashti equations. The Othmer-Tobias as well as the Bancroft equations were subsequently selected to correlate the compositions of the tie lines at equilibrium where the fitted parameters are derived. In addition, the Guan’s equation was utilized to correlate the experimental binodal curves. Finally, the effectively excluded volume (EEV) was determined and the values were found to increase with pH.

Influence of the Molecular Weight of Polymer on the Poly Vinyl Pyrrolidone and Zinc Sulfate Phase Diagram of Aqueous Two-Phase Systems

The study obtained the Liquid – Liquid Equilibrium (LLE) for Aqueous Two-Phase Systems (ATPSs) containing poly (vinyl pyrrolidone) (PVP) (10000, 24000, and 40000) and zinc sulfate at 298.15 K. The phase area is expanded according to the increased molecular weight of the polymer. Density and refractive indices were employed as the physical properties for obtaining phase composition and end of tie-line evaluations. The effect of molecular weight is discussed in relation to binodal curve, Tie-Line Length (TLL), and Slope of Tie Line (STL) determinations. Following the increase in polymer molecular weight value, the TLL increased and STL slightly decreased. Accordingly, Pirdashti’s equation was used to correlate binodal curve evaluations of these systems. Furthermore, tie-line data points were correlated by Othmer-Tobias, Hand, and Bancroft equations. Finally, the study determined the Effective Excluded Volume (EEV) of salt into the PVP aqueous solution.

Phase Equilibria of Aqueous Two-Phase Systems of PEG with Sulfate Salt: Effects of pH, Temperature, Type of Cation, and Polymer Molecular Weight

The present work reports the liquid–liquid equilibrium (LLE) measurements and the construction of binodal curves for polyethylene glycols (PEG) + zinc sulfate/ammonium sulfate + water at three different temperatures (298.15, 303.15, and 308.15 K) and pH values (3.00, 4.70, and 5.21). PEGs with different molecular weights of 2000 g·mol–1 (PEG 2000), 3000 g·mol–1 (PEG 3000), and 8000 g·mol–1 (PEG 8000) were chosen for this study. The phase composition was obtained by measuring the refractive index (nD) and density (ρ) and was further used to obtain the tie-line length (TLL) and the slope of tie-line (STL). The tie-lines are reported at different polymer lengths, pH values, and temperatures. The values of the effective excluded volume (EEV) were employed to analyze the effect of the parameters on the binodal curves. Moreover, the impact of those parameters on the TLL and STL and plait point are discussed and compared with the results of the literature. Furthermore, the binodal curves data and the tie-lines’ ends were fitted using some semiempirical equations with satisfactory results. Finally, the UNIFAC is used to calculate the LLE data of the above system and the adjusted binary group interaction parameters of the model were reported.

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.

Phase equilibria measurements and correlation of aqueous solvent of PEG4000 with rubidium chloride at (288.15, 298.15, and 308.15) K

The phase equilibria of ternary system polyethylene glycol with molar mass of 4000 g∙mol−1(PEG 4000), rubidium chloride (RbCl) and water (H2O) were determined at T=(288.15, 298.15, 308.15) K. Results show that there is only solid-liquid equilibrium (SLE) relationship in the system at 288.15 K, both of solid-liquid equilibrium (SLE) and liquid-liquid equilibrium (LLE) are found in the system at 298.15 K and 308.15 K. The phase diagram at 288.15 K was divided into 3 areas including the region L (unsaturated liquid phase), the region L + S (saturated solutions with a solid phase RbCl) and the region L + 2S (saturated liquid phase with two solid phases of PEG4000 and RbCl) and the solubility of RbCl decreased with PEG4000 increasing. The complete phase diagrams at 298.15 K and 308.15 K including 6 areas (L (unsaturated liquid phase), 2L (aqueous two-phase), L + 2S (saturated liquid phase with two solid phases of PEG4000 and RbCl), 2L + S (two liquids with one solid phase RbCl), and 2 areas of L + S (saturated solutions with one solid phase RbCl) were constructed. Furthermore, the binodal curves, compositions, length of the tie-line (TLL) and slope of tie-line (STL) were obtained for these mixed solvent systems at 298.15 K and 308.15 K. Three nonlinear expressions, proposed by Mistry, Hu, and Jayapal, were used to fit the binodal curves. The data of tie-line were correlated by using Othmer-Tobias equations, Bancroft equations, Hand equation, Bachman equations and the Chen-NRTL model. All the presented results, both the experimental and calculated data, show convincing values.

Measurement and correlation of phase equilibria in aqueous two-phase systems containing ionic liquid ([EOMiM]Br) and potassium citrate/ammonium citrate/potassium tartrate at different temperatures

An aqueous two-phase system (ATPS) containing an ionic liquid (1-(2-methoxyethyl)-3-methylimidazolium bromide) and three organic salts (K3C6H5O7, (NH4)3C6H5O7, and K2C4H4O6) at different temperatures was designed. Binodal data were correlated using two empirical equations, and tie-line data were fit with the utilization of Bancroft and Othmer-Tobias equations. In the systems investigated, three conclusions were drawn from the study of the phase-forming ability of salt through effective excluded volume, Gibbs free energy of ions, and the phase diagram. First, if the same cations of salt were present, the ability of salt to form phases increased with increasing valence of the anion. Second, the larger the effective excluded volume, the stronger the aforementioned ability of salt in forming phases. Third, salt had more ability to form phases if cations (or anions) contained in the salt possessed higher negative Gibbs free energy when the cation (anion) of the salt was the same. The effect of temperature on ATPSs was also investigated. It was found that it was easier to form ATPSs at lower temperature, and the tie-line slope showed growing absolute values as the temperature was decreased.

Thermodynamic Modeling of Aqueous Two-Phase Systems Composed of Macromolecules and Sulfate Salts at pH 2.0

Liquid–liquid equilibrium data of aqueous two-phase systems (ATPS) composed of polyethylene glycol (PEG) 8000 + sodium sulfate + water, PEG 8000 + ammonium sulfate + water, and PEG 8000 + magnesium sulfate + water at T = 298.15, 308.15, and 318.15 K and pH 2.0 were determined. The universal function activity coefficient (UNIFAC) model was correlated to the experimental tie-line data, and the root-mean-square deviations (RMSDs) between experimental and calculated data were considered in the calculation. The effects of temperature and cation type on the spinodal curves were evaluated. The salting-out effect was studied by the determination of the effective excluded volume (EEV). Rising temperature resulted in an increase in the biphasic region and tie-lines. Regarding the cation type, the phase-separation abilities followed the order Mg2+ > Na+ > (NH4)+. Increases in the overall composition of the systems resulted in increased tie-line lengths. The tie-line slope absolute values also tended to rise with inc...

Phase equilibrium and partitioning of cephalosporins (cephalexin, cefazolin, cefixime) in aqueous two-phase systems based on carbohydrates (glucose, fructose, sucrose, maltose) / acetonitrile

In recent decades, the use of aqueous two-phase system (ATPS) for bio-separation engineering has attracted increasing interest. In this work, ATPSs based on carbohydrates and acetonitrile were used to explore the partitioning behavior of cephalosporin antibiotics including cephalexin, cefazolin, and cefixime. For this purpose, four ATPSs containing acetonitrile and glucose, fructose, sucrose, and maltose have been studied. Initially, the phase diagrams were acquired at 300 K and then correlated by the Merchuk equation. The results showed that the ATPS composed of disaccharides have a broader two-phase region than monosaccharides. Furthermore, for the studied systems, tie-lines were obtained and their accuracy was examined by Othmer-Tobias and Bancroft equations. Moreover, tie-lines length and slope of tie-lines were determined. Besides, the partition coefficient of cephalosporins in four different ATPSs and a total of 48 tie-lines were investigated. Based on the results, it can be concluded that by increasing the concentration of carbohydrates, the partition coefficient increases. The maximum partitioning coefficient of cephalexin and cefazolin were obtained to be 19.2 and 17, respectively, with a recovery yield of 93% in the carbohydrate phase, which corresponds to the system (16 wt % glucose + 50 wt % acetonitrile + water). While the highest partitioning coefficient of cefixime was 6.4, with a recovery percentage of 81% for the system (16 wt % sucrose + 50 wt % acetonitrile + water). The results of this work indicate that these systems have a potential for separation and recovery of the understudied antibiotics.

Phase equilibria of CsCl-polyethylene glycol (PEG)-H2O at 298.15 K: Effect of different polymer molar masses (PEG1000/4000/6000)

The phase equilibrium of CsCl-polyethylene glycol (PEG) 1000 – H2O, solid-liquid equilibria (SLE), and liquid-liquid equilibria (LLE) data for aqueous two – phase system (ATPS) containing CsCl and PEG4000/6000 was determined at 298.15 K. The equilibrium phase compositions, binodal curves, tie-line length (TLL), and slope of tie-line (STL) for the aqueous two phase systems were determined. Furthermore, three non-linear expressions developed by Mistry, Hu, and Jayapal were used to correlate the binodal data, the effective excluded volumes (EEV) were calculated from binodal curve data, the tie-line data were correlated with Othmer-Tobias and Bancroft equations. It was found that the salting out effect is greater with larger molecular mass of PEG as the EEV of PEG6000 is larger than PEG4000. As the molecular mass of PEG increased, the binodal curve shifted toward the origin, which increased the liquid-liquid biphase region.

Development of minimum tie line length method for determination of minimum miscible pressure in gas injection process

Gas injection process is a very important technology in enhanced oil recovery. Minimum miscible pressure is one of the key parameters in gas injection processes. Various experimental methods such as slim tube are used to measure MMP. These methods are costly and time consuming. Recently computational methods are used in order to achieve a cost-effective and reliable technique to evaluate MMP. In this work, a new methodology has been proposed for determination of MMP using the minimum tie line length method. A real mixing cell model was developed to estimate the MMP, MME and key tie lines. This method is simple, robust, and faster than conventional one-dimensional simulation of slim tube. The new mixing cells method can accurately determine the whole key tie lines to a shift, regardless of the number of injection gas and reservoir fluid components. Unlike other methods of mixing cells, this method automatically corrects dispersion by additional contacts to achieve the low variation domain of tie line slope. Also, the determination and implementation of the minimum miscibility enrichment are investigated.

Effect of 1-ethyl-3-methylimidazolium tetrafluoroborate on the phase equilibria for systems containing 5-hydroxymethylfurfural, water, organic solvent in the absence and presence of sodium chloride

HMF (5-hydroxymethylfurfural) is a well-known promising product from hexose dehydration used for production of biofuels and chemicals. Liquid-liquid extraction is an essential process in HMF production to recover HMF from reaction medium. One of the important parameters needed in the extraction process design is liquid-liquid equilibrium (LLE) data. Organic solvent (methyl isobutyl ketone or 2-pentanol) was applied as extraction solvent to induce phase separation and extract HMF from the aqueous solution in the presence of the ionic liquid [EMIM][BF4] (1-ethyl-3-methylimidazolium tetrafluoroborate) and NaCl (sodium chloride). The aim of this study is to investigate the effect of [EMIM][BF4] on the phase equilibria of methyl isobutyl ketone (MIBK) or 2-pentanol, HMF, water systems in the absence and presence of NaCl at 313.15 K and atmospheric pressure (0.1 MPa). The separation factor and the distribution coefficient of HMF were obtained for interpreting liquid-liquid extraction performance. The results indicated that the presence of [EMIM][BF4] caused negative effect on the LLE of organic solvent-HMF-water systems. The slope of tie-lines became more negative with increasing [EMIM][BF4] concentration, indicating lower HMF distribution coefficients and separation factors. However, the presence of NaCl in the HMF aqueous ionic liquid solution can enhance both the separation factor and the distribution coefficient making the HMF extraction more favourable with the HMF distribution coefficient values higher than 1 over the whole range of initial HMF concentrations. According to the results in the present study, MIBK was found superior as an extraction solvent for HMF in the presence of [EMIM][BF4] and NaCl exhibited from the better extraction performance with the separation factors 2.0 times higher than those of 2-pentanol. Furthermore, the NRTL activity coefficient model satisfactorily correlated all the experimental phase equilibrium data provided in this study. The RMSD (root mean square deviations) of the NRTL model were 0.97% and 0.63% for the investigated LLE systems with MIBK and 2-pentanol as solvent in the absence of NaCl, respectively. Whereas, the RMSD of the LLE systems containing NaCl were 0.28% for MIBK-HMF-water-[EMIM][BF4]-NaCl and 0.90% for 2-pentanol-HMF-water-[EMIM][BF4]-NaCl.

Phase equilibria of aqueous mixtures of PEG with formate salt: Effects of pH, type of cation, polymer molecular weight and temperature

Liquid-liquid equilibrium (LLE) data for poly (ethylene glycol) (PEG) of different molecular weights (600, 1500, 3000, 6000) + sodium formate (NaCHO2), potassium formate (KCHO2) + water at different temperatures (298.15 and 308.15 K) and for PEG (1500) + sodium formate + water at different pH values (8.05, 9.06, 10.92), were determined experimentally. The tie lines and plait point are reported at different PEG molecular weight, pH, temperature and type of cation. Furthermore, the effect of those parameters on binodal curve, tie-line length (TLL) and slope of tie line (STL) are discussed in detail by comparing the results to that of literature data. The effective excluded volume (EEV) values obtained from the LLE data were used to study the effect of the parameters on the binodal curves. The phase composition and the tie-lines’ ends were obtained by measuring the density (ρ) and refractive index (nD). Furthermore, the binodal curves and the tie-line compositions were well-fitted by using some semi empirical equations.

Influence of the Temperature, Type of Salt, and Alcohol on Phase Diagrams of 2-Propanol + Inorganic Salt Aqueous Two-Phase Systems: Experimental Determination and Correlation

The liquid–liquid equilibriums (LLEs) for 2-propanol + tripotassium phosphate + water at 298.15, 308.15, and 318.15 K and 2-propanol + dipotassium hydrogen phosphate + water at 298.15 K were measured. The binodal curves of 2-propanol + potassium sulfate/potassium sulfite + water at 298.15 K were measured and compared. Accordingly, the experimental binodal data were correlated using Merchuk, Hu, and Pirdashti equations, and the tie-line compositions were correlated using Othmer–Tobias and Bancroft equations. The effect of temperature, anion type, and length of alcohol chain on the binodal curve, tie-line length (TLL), slope of tie-line (STL), and phases’ physical properties were studied. It was found that an increase in salt’s hydrophobicity and alcohol’s carbon number in low temperature led to the expanding biphasic region and approaching the binodal curve to the origin. The phase-forming ability of different anions was studied using effective excluded volume (EEV) model, and the relation between the EEV ...

Influence of the molecular weight of polymer, temperature and pH on phase diagrams of poly (ethylene glycol) + di-potassium tartrate aqueous two-phase systems

Phase diagrams and liquid – liquid equilibrium (LLE) data for aqueous two-phase systems (ATPSs) containing di-potassium tartrate (DPT) and poly (ethylene glycols) (PEG) (1500 and 6000) have been determined experimentally at different pH values (6.41, 7.74 and 9.05) and temperatures (298.15 and 308.15 K). The effect of molecular weights of the PEG, temperatures, and pH on the binodal curve, tie-line length (TLL) and slope of tie line (STL) was studied. It was found that an increasing in PEG molecular weight, temperature and pH led to the binodal curve displacement towards the origin and increasing two-phase region. Accordingly, the various empirical equations were used to correlate the binodal curves of these systems such as Merchuk equation and Pirdashti equation and the tie-line compositions were correlated using Guan equation. Also, the refractive index and density of ternary (PEG 1500/6000 + di-potassium tartrate (DPT) + water) system have been measured. The density and refractive index were employed as the physical properties to obtain the phase composition and the tie-lines ends and show a linear variation with mass fraction of the polymers and the salt. Also, it was found that TLL affects the density of ATPS. The density difference between the phases (Δρ) increased with an increment in the TLL and pH values and PEG molecular weights and temperatures. Finally, the salting-out ability of the systems were explained by using “Effective Excluded Volume (EEV) model”.