Water Aqueous Two-phase Systems Research Articles

Phase diagrams of PEG1000,1500,2000,4000,6000 + lithium citrate + water ATPSs, and the partitioning of salbutamol at T = 298.15 K

Salbutamol is a drug used to treat the pulmonary diseases by ameliorate the medium and large airways in the lungs. Partitioning of salbutamol drug on the aqueous two-phase systems (ATPSs) of PEG1000,1500,2000,4000,6000 + trilithium citrate + water was determined at T = 298.15 K. The effect of molecular mass of polymer (MMP) on the binodal and tie-line compositions were studied. Results showed that the biphasic area was extended as the MMP was increased. The salting-out ability were quantified using the Setschenow model, and the binodal curves were modeled by a nonlinear 3-parameter equation. Furthermore, electrolyte Wilson along with the osmotic virial models have adequately been implemented to fit the tie-line compositions. Also, the studied ATPSs were implemented to study the partitioning of salbutamol drug on the salt-affluent and polymer-affluent phases. It is observed that, ATPSs of PEG1000 is premium to extract the salbutamol to the polymer-affluent phase, where, the ATPSs of PEG6000 is more favorable to extract the drug to the salt-affluent phase.

Temperature Effect on the Phase Equilibrium of Polyethylene Glycol 2000 + Trilithium Citrate + Water Aqueous Two-Phase Systems at T = 288.15, 298.15, 308.15, and 318.15 K

Binodal and tie-line mass fractions for ternary polyethylene glycol 2000 + trilithium citrate + water aqueous two-phase systems (ATPSs) were reported at T = 288.15, 298.15, 308.15, and 318.15 K experimentally and modeled thermodynamically. It was found that the extent of the two-phase area of the liquid–liquid equilibrium region was increased as the temperature increased. Also, binodal curves were properly modeled with two nonlinear models, and both models have been successful in fitting the binodal data. Furthermore, the osmotic virial, modified nonrandom two-liquid (m-NRTL), and electrolyte-Wilson models have successfully been implemented in the modeling of the tie-line mass fractions. The quality of fitting with the electrolyte-Wilson and specially m-NRTL models is good, and the uncertainty of the modeled data is in the range of the uncertainty of the experimental data. Also, the salting-out coefficient (ks) of a Setschenow-type equation was applied as a quantitative measure of the salting-out ability. The results of the present work introduce a green and environmentally friendly ATPS for liquid–liquid extraction and purification purposes, which can be used in the separation and purification of drugs, biomaterials, and foods.

New Insights into the Partitioning of Phenothiazine Dyes in Aqueous Two-Phase Systems

Aqueous two-phase systems (ATPSs) have proven to be efficient and environmentally safe methods for extracting chemical species. However, the driving forces behind the partition of solutes in these systems are still little understood. A complete thermodynamic partitioning of phenothiazine dyes was investigated in poly(ethylene oxide) (PEO) + salt + water ATPSs. Standard transfer parameters (Gibbs free energy change (ΔtrGo), enthalpy change (ΔtrHo) and entropy change (TΔtrSo)) were evaluated, and their dependence on the dye structure, electrolyte nature and tie line length (TLL). All phenothiazine dyes are concentrated predominantly in the polymer enriched phase, with ΔtrGo values ranging from -4.1 up to -13.4 kJ mol-1. Due to the dye-PEO attractive interactions that occur mainly via benzene condensed ring present in the structures of phenothiazine dyes, the partitioning of these dyes was enthalpically driven, with -11.4 ≥ ΔtrHo ≥ -52 kJ mol-1 and -4.93 ≥ TΔtrSo ≥ -38 kJ mol-1.

Partitioning of cocaine and its adulterants in aqueous two-phase systems: An alternative drug identification method

The partitioning behaviors of cocaine freebase (CoF), cocaine hydrochloride (CoH), and a range of adulterants (procaine (PRO), phenacetin (PHE), caffeine (CAF), benzocaine (BEN), and lidocaine (LID)) in aqueous two-phase systems (ATPS) were evaluated, with the aim of developing a selective and efficient alternative technique for the identification of cocaine in samples confiscated by the police. The partition coefficients (KS) of all the solutes were obtained in ATPS formed using a macromolecule (PEO1500 or L35 copolymer), a salt (Na2SO4 or Li2SO4), and water. The KS values were consistently higher than 1 and increased with increase of the tie-line length. For the PEO1500 + Li2SO4 + water ATPS at pH 6.0, the KS values increased in the order: KLID < KPRO < KCAF < KCoF < KCoH < KPHE < KBEN. The greatest effect on the partitioning was shown by the polymer hydrophobicity, followed by the nature of the electrolyte and the pH of the ATPS. The ratio between two KS values for two different ATPS types was used as a strategic parameter for distinguishing between the two forms of cocaine, as well as between cocaine and the adulterants. The K12/K6 ratio, where K6 and K12 are the KS values for the PEO1500 + Li2SO4 + water ATPS at pH 6.0 and 12.0, respectively, enabled CoH to be distinguished from all the other solutes studied. In addition, the effect of the hydrophobicity of the polymer on the KS values was fundamental for distinguishing CoF from the other solutes.

Liquid–Liquid Equilibrium of Imidazolium Ionic Liquids + Phosphate + Water Aqueous Two-Phase Systems and Correlation

Binodal curves of the aqueous 1-butyl-3-methylimidazolium tetrafluoroborate([C4mim]BF4) + kosmotropic salt (Na3PO4,(NH4)3PO4) + water aqueous two-phase systems were determined experimentally at 288.15, 298.15, 308.15 and 318.15 K. Three empirical equations were used to correlate the binodal data. All three empirical equations reproduce the data with a high degree of precision. The effect of temperature on the binodal curves was studied. Corresponding to two different salts, the two-phase area decreases with increasing temperature. From the binodal model for these systems, the effective excluded volumes (EEV) were obtained. The binodal curves and EEV both indicate that the salting-out abilities are in the order: Na3PO4 > (NH4)3PO4. And, the reliability of the tie-line compositions was proved by the empirical correlation with the Othmer–Tobias and Bancroft equations. The results show that the salting-out strength is greater at lower temperatures. Additionally, a relatively simple two-parameter equation was used for the correlation of the tie-line data.

Partitioning performance of molybdenum in poly (ethylene glycol) + sodium sulfate + water aqueous two-phase systems

Partition performance of molybdenum (VI) by aqueous two-phase systems (ATPSs) composed of poly (ethylene glycol) (PEG1000, PEG2000 and PEG4000)+sodium sulfate+H2O without any extractant was systematically studied. Response surface optimization method was applied to study the effects of different factors such as, the type and concentration of PEG, sodium sulfate concentration, molybdenum concentration and temperature on the phase volume ratio, partition coefficient and extraction rate of molybdenum. The experimental results showed that the phase volume ratio changes with all four parameters, resulting from hydration of sodium sulfate, dehydration of increasing temperature and replace of molybdenum to water. The partitioning coefficient and extraction rate of molybdenum increases as increasing sodium sulfate concentration being of hydration of sodium sulfate, and also increases with increasing temperature, indicating that the transfer process of molybdenum from the salt-rich phase to the PEG-rich phase is endothermic. With the increase of PEG molecular weight (PEG1000, PEG2000 and PEG4000), the phase volume ratio decreases and partitioning coefficient and extraction rate of molybdenum goes up. The extraction mechanism can be deduced that molybdenum was extracted into PEG-rich phase by electrostatic attraction between polymolybdate anion and protonated COC bond in PEG molecule due to relatively high hydrophobicity of polymolybdate anion under the salting-out effect of phase-forming sodium sulfate by the change of initial and equilibrium pH in aqueous phase, FTIR and Raman spectrum analysis. A better result on extracting and separating molybdenum was achieved by applying the proposed method to the leaching liquor of low-grade molybdenite concentrate.

Liquid-liquid equilibrium of the ternary ammonium salt + poly(propylene glycol) + water system

Aqueous two-phase systems (ATPS) have been investigated as alternative systems for liquid-liquid extraction. Many ATPS phase diagrams for poly(ethylene glycol) (PEG) have been reported, but little information is available regarding liquid-liquid equilibrium data for poly(propylene glycol) (PPG). In the present work, the phase diagrams for PPG425 + ammonium acetate + H2O, PPG425 + ammonium tartrate + H2O, PPG425 + ammonium citrate + H2O, PPG425 + ammonium formate + H2O, and PEG900 + ammonium citrate + H2O were experimentally determined at 283.2, 298.2, and 313.2 K. The study of statistic treatment was introduced by a computation method NRTL model. This program is a method to estimate the energetic parameters of the studied systems. The binary interaction of the calculated parameters are very important for designing or optimizing industrial process. The results were considered very satisfactory with global root mean square deviations of 1.82%. Factors affecting the phase-forming capability of the polymer + electrolyte + water ATPS, such as anion structure, temperature, polymer hydrophobicity were evaluated. For all the systems, the increase in temperature enlarges the area of the phase diagram, indicating the enthalpic contribution to the formation of the biphasic system. The ability of the different anions to induce ATPS formation with PPG425 followed the order: C4H4O62− (tartrate) > C6H6O72− (citrate) > C2H3O2− (acetate) > CHO2−(formate). The ATPS involving PPG425 showed a larger two-phase area than that observed in the system formed by PEG900, which is more hydrophilic than PPG425.

Driving forces for chymosin partitioning on the macromolecule-salt aqueous two phase system

Aqueous two-phase systems (ATPSs) are strategic liquid–liquid systems for extraction and purification of compounds. However, only a few studies have evaluated the thermodynamic parameters that allow comprehension of the partition process of different molecules. Here, we investigated the chymosin (Chy) partitioning behavior in macromolecule+salt+water ATPSs by obtaining the partition coefficient (KChy), Gibbs free energy change of transference (ΔGtr,Chy∞), enthalpy change of transference (ΔHtr,Chy∞), and entropy change of transference (ΔStr,Chy∞), at infinite dilution, and their dependence on the ATPS properties. Chy transfer from the bottom to the top phase of the ATPS was enthalpically driven, with −4.84kJmol−1<ΔHtr,Chy∞<−170.34kJmol−1 and −11.69Jmol−1K−1<ΔStr,Chy∞<−558.95Jmol−1K−1 characterizing an enthalpy–entropy compensation process; −1.36kJmol−1<ΔGtr,Chy∞<−3.77kJmol−1. ΔHtr,Chy∞ became more negative as the tie-line length increased, showing that specific macromolecule–Chy interactions determine the enzyme concentration in the top phase. The nature of the cation/anion, hydrophobic/hydrophilic balance of the top phase, and macromolecule molar mass influence the intermolecular interaction between Chy and top phase components, changing the enzyme partition behavior. Negative ΔStr,Chy∞ parameters were attributed to the Chy transfer from a higher (bottom phase) to the lower (top phase) configurational entropy region.

Phase diagrams, densities and refractive indexes of poly(ethylene oxide) + organic salts + water aqueous two-phase systems: Effect of temperature, anion and molar mass

The application of aqueous two-phase systems (ATPSs) at the industrial level requires systems formed by non-toxic substances to decrease the negative impact on the environment. Organic salts such as sodium citrate, sodium tartrate and sodium succinate have been utilized in order to fulfill this objective. In this work, ATPSs formed by poly(ethylene oxide), PEO, with molar mass 10,000 or 35,000gmol−1, organic salts and water, namely PEO10000+sodium citrate+water, PEO10000+sodium tartrate+water, PEO10000+sodium succinate+water and PEO35000+sodium citrate+water ATPSs at (283.15, 298.15 and 313.15)K have been studied. Effects of temperature, anion and polymer molar mass on the phase diagrams, as well as, the densities and refractive indexes of both phases of the ATPSs were evaluated. The segregation process was endothermic and entropically driven for all ATPSs. The biphasic region on the phase diagrams increased as the molar mass of PEO increased. In addition, the biphasic region also increased in relation to the anions studied: citrate>tartrate>succinate. The consistency of the tie-line data was ascertained by applying the Othmer–Tobias correlation.

Hydrophilic organic/salt-containing aqueous two-phase solvent system for counter-current chromatography: A novel technique for separation of polar compounds

Hydrophilic organic/salt-containing aqueous two-phase system composing of ethanol, water and ammonium sulfate for separation polar compounds was investigated on multilayer coil associated with J-type HSCCC devices. Compared to the classical polar solvent system based on 1-butanol–water or PEG1000–ammonium sulfate–water, the water content of upper phase in ethanol–ammonium sulfate–water systems was from 53.7% to 32.8% (wt%), closed to PEG1000–ammonium sulfate–water aqueous two-phase systems and higher than 1-butanol–water (22.0%, wt%). Therefore, the polarity of ethanol–ammonium sulfate–water is in the middle of 1-butanol–water and PEG–ammonium sulfate–water system, which is quite good for separating polar compounds like phenols, nucleosides and amino acids with low partition coefficient in 1-octanol–water system. The retention of stationary phase in four elution mode on type-J counter-current chromatography devices with multilayer coil column changed from 26% to 71%. Hydrodynamic trend possess both intermediate and hydrophilic solvent system property, which closely related to the composition of solvent system. The applicability of this system was demonstrated by successful separation of adenosine, uridine guanosine and cytidine.

Liquid–liquid equilibria of ionic liquid 1-(2-methoxyethyl)-3-methylimidazolium bromide + potassium carbonate, potassium phosphate, dipotassium phosphate + water aqueous two-phase systems

Binodal curves of 1-(2-methoxyethyl)-3-methylimidazolium bromide+potassium carbonate, potassium phosphate, dipotassium phosphate+water aqueous two-phase systems were determined experimentally at T=288.15, 298.15 and 308.15K, respectively. Effect of temperature on binodal curves was studied. Two empirical equations were used for reproducing the experimental binodal data. Effective excluded volume (EEV) theory was used to investigate the phase-forming strength of salts PO43−>HPO42−>CO32−. Additionally, the tie-line data were correlated by the Othmer-Tobias, Bancroft and Setschenow-type equations.

Liquid–Liquid Equilibrium of Some Aliphatic Alcohols + Disodium Tartrate + Water Aqueous Two-Phase Systems at 298.15 K

In the present work, the liquid–liquid equilibrium of 1-propanol, 2-propanol, 2-methyl-2-propanol, or 2-butanol + disodium tartrate + water aqueous two-phase systems was studied. The experimental binodal curves and tie-line compositions at 298.15 were reported, and the effect of temperature on the phase separation ability of these systems was studied using cloud-point data as a function of alcohol mole fractions at the (293.15 to 323.15) K temperature range with 5 K successive intervals. The effective excluded volume (EEV) model was also was used to describe the salting-out ability in the studied systems. A simple three-parameter empirical equation was successfully used for the correlation of the binodal data, and the modified electrolyte Wilson model for mixed solvent electrolyte systems was used for the correlation of the tie-line compositions. The restricted binary interaction parameters were also reported. Good agreement between the experimental and the calculated tie-line compositions was observed.

Phase diagram and thermodynamic modeling of PEO + organic salts + H 2O and PPO + organic salts + H 2O aqueous two-phase systems

The phase diagrams of PEO1500 + sodium tartrate + water, PPO400 + sodium tartrate + water, PEO1500 + sodium succinate + water, PPO400 + sodium succinate + water, PEO1500 + sodium citrate + water, PPO400 + sodium citrate + water and PPO400 + sodium acetate + water aqueous two-phase systems were determined at (283.15, 298.15, and 313.15) K. Both equilibrium phases composition were analyzed by conductimetry and refractive index. In this paper, the influences of polymer hydrophobicity, salt nature and temperature on the phase diagram were analyzed. The phase separation processes was endothermic and the hydrophobic increase make easier the phase splitting, while the electrolyte capacity to induce phase separation follow the order: citrate > tartrate > succinate. The consistency of the tie-line data was ascertained by applying the Othmer–Tobias correlation. The experimental data were correlated with the NRTL model for the activity coefficient, with estimation of new interaction energy parameters. The results, analyzed in terms of root mean square deviations between experimental and calculated compositions, were considered satisfactory.

Modeling of the partitioning of membrane protein and phase equilibria for Triton X-100–salt aqueous two-phase systems using a modified generalized multicomponent osmotic virial equation

The partitioning of membrane protein and liquid–liquid equilibria for Triton X-100–salt–water aqueous two-phase systems were measured at 293.15 K. A generalized model was proposed to predict both partitioning of membrane protein and phase behavior of the surfactant aqueous two-phase systems. By using part of liquid–liquid equilibria (LLE) data, Triton X-100–Na 2SO 4 and Triton X-100–Na 2CO 3 aqueous two-phase systems were successfully predicted. The results showed that most of the average absolute deviations were less than 1.0% (w/w). The partition coefficient of membrane protein in Triton X-100–Na 2SO 4 and Triton X-100–Na 2CO 3 aqueous two-phase systems were also successfully predicted. The results showed that most of the average absolute deviations of the two systems were less than 5% and 8%, respectively. The model could give good representation of partitioning of membrane protein and the phase diagrams.

PEG + Potassium Phosphate + Urea Aqueous Two-Phase Systems: Phase Equilibrium and Protein Partitioning

Liquid−liquid equilibria of poly(ethylene glycol) (PEG) + potassium phosphate + urea + water aqueous two-phase systems were studied for different PEG molecular weights and pHs. Experimental techniques and analytical methods are described. Equilibrium data were obtained for PEG (1450, 3350, 10000) + potassium phosphate (pH 7 and 9) + urea (6 mass%) + water aqueous two-phase systems at 25 °C. Four tie lines were measured for each system. The partitioning behaviors of lysozyme, catalase, and β-galactosidase were studied in these systems at 25 °C, at pH 7 and 9, and at the urea concentrations 3 and 6 mass %.

Measurement of phase diagrams for new aqueous two-phase systems and prediction by a generalized multicomponent osmotic virial equation

The liquid–liquid equilibria for ethylene oxide–propylene oxide random copolymer (EOPO)–hydroxypropyl starch (HPS)–water aqueous two-phase systems with various polymer molecular weights were measured at 298.15 K. A generalized multicomponent osmotic virial equation was proposed to predict the phase behavior of new aqueous two-phase systems. By using the vapor–liquid equilibrium (VLE) and/or part of liquid–liquid equilibria (LLE) data (as few as possible), the LLE data of polyethylene glycol (PEG)–HPS, EOPO–HPS and EOPO–salt aqueous two-phase systems were successfully predicted. The results show that the model can give good representation of the phase diagrams.

Measurement and correlation of partition coefficients of amino acids in dextran+poly(ethylene glycol)+water aqueous two-phase systems.

The partition coefficients of three amino acids (tryptophan, tyrosine and threonine) in various dextran+polyethylene+water aqueous two-phase systems were measured. The partition coefficients of six amino acids (glycine, phenylalanine, isoleucine, tryptophan, tyrosine and threonine), obtained in a previous and the present studies, were correlated by using the osmotic virial equation. The partition coefficients of amino acids were predicted successfully by using a hydrophilic group-parameters introduced in this study.

Measurement and correlation of partition coefficients of hydrolytic enzymes for dextran+poly (ethylene glycol) + water aqueous two-phase systems at 20°C

The partition coefficients of hydrolytic enzymes, α-amylase, β-amylase and glucoamylase for the dextran (DEX)+poly(ethylene glycol) (PEG)+water aqueous two-phase systems with various polymer molecular weights were measured at 20°C. The partition coefficients obtained were correlated by using a mod fied Flory-Huggins equation which was empirically proposed for aqueous systems. The interaction parameters required were determined by fitting the model to the experimental data. The partition coefficients could be correlated with good agreement.

Measurement and correlation of liquid-liquid equilibria for dextranpoly(ethylene glycol)water aqueous two-phase systems at 20°C

The liquid-liquid equilibria (LLE) for the dextranpoly(ethylene glycol)water aqueous two-phase systems with various polymer molecular weights were measured at 20°C. The molecular weight distributions of dextran (DEX) and poly(ethylene glycol) (PEG) in the PEG-rich phase (top phase) and DEX-rich phase (bottom phase) were also measured. To take into account deviations from random mixing, the interaction term of the conventional Flory-Huggins equation was empirically modified. The molecular weight distribution of DEX was expressed by a Γ distribution function because the DEX sample used showed a wide molecular weight distribution though the PEG samples were almost monodispersed. LLE and molecular weight distributions were correlatet successfully using a continuous thermodynamic approach.