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

Abstract

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 increasing temperature. Increasing the ATPS constituent concentrations resulted in an increase in the phase densities. The increase in temperature resulted in an increase in the salting-out effect. The exclusion volume values increased in the following order: (NH4)+ < Na+ < Mg2+. The overall mean deviation between the experimental and correlated LLE compositions for the PEG 8000 + ammonium sulfate + water, PEG 8000 + magnesium sulfate + water, and PEG 8000 g mol–1 + sodium sulfate + water was 3.901%. The results of the UNIFAC model agree with the experimental tie-line values. This allows the use of this model to obtain reliable data for this system, thus reducing the number of experiments to be performed for a processing design.

Effect of Temperature on the Phase Equilibria of Poly(vinylpyrrolidone) 10000 + Trilithium Citrate + Water Aqueous Two-Phase System and Partitioning of Curcumin at T = 298.15, 308.15, and 318.15 K

“…18 Several polymer−salt systems have been studied previously, 10,11,19−21 but the role of temperature in these systems is not well investigated. Muniz et al 11 containing PEG, 20,22,23 poly(ethylene glycol) dimethyl ether, 10,19,24,25 and poly(vinylpyrrolidone) (PVP). 26−28 PVP is a low-cost, stable, and water-soluble polymer that has applications in ATPSs to extract or purify the biomolecules.…”

“…Muniz et al . studied the phase formation of poly­(ethylene glycol) (PEG) with potassium phosphate at T = 298.15 K. In addition, numerous studies are done on the polymer–salt systems containing PEG, ,, poly­(ethylene glycol) dimethyl ether, ,,, and poly­(vinylpyrrolidone) (PVP). − PVP is a low-cost, stable, and water-soluble polymer that has applications in ATPSs to extract or purify the biomolecules …”

Extraction of protease from ora‐pro‐nobis ( Pereskia aculeata Miller) and partial purification in polyethylene glycol + sodium phosphate aqueous two‐phase system

“…As can be seen, for all systems, PEG is excluded from the lower phase, and the opposite is observed in the upper phase, where the polymer is present in a high concentration. This effect is commonly observed in PEG‐salt systems (de Souza et al., 2014; Nascimento et al., 2018; Sampaio et al., 2020). The increase in the composition of the systems increased the values obtained for TLL.…”

“…For this reason, the presence of a homogeneous system is not thermodynamically favorable, and for the reduction of free energy, the system is separated into two phases. Consequently, less salt is used for PEG saturation and phase separation, and the binodal curve moves closer to the axes (Albertsson, 1970; Sampaio et al., 2020).…”

Phase Equilibria of the Ternary System of Lithium Sulfate + Polyethylene Glycol (PEG3000) + Water at Different pH: Experiment Determination, Correlation, and Thermodynamic Modeling

“…The local composition thermodynamic models were widely used to describe the ATPSs. Some of the well-known models are the Wilson, NRTL, UNIQUAC, and UNIFAC , along the mNRTL-NRF, UNIQUAC-NRF, and the modified Wilson. , The UNIQUAC equation was developed based on the two-fluid theory, and it has been widely employed in the design of distillation and extraction processes which involve the calculation of the fluid-phase equilibria due to its accuracy . Similarly, the UNIQUAC-NRF is derived from the excess Gibbs energy and is heavily utilized to determine the activity coefficient of the binary electrolyte solutions .…”