Study of liquid-liquid equilibria in aqueous two-phase systems formed by poly (ethylene glycol) (PEG) and sodium thiosulfate pentahydrate (Na2S2O3.5H2O) at different temperatures

Abstract

This study aimed at providing experimental liquid-liquid equilibrium (LLE) data for aqueous two-phase systems (ATPSs) formed by poly (ethylene glycols) (PEG) of different molecular weights (1500 or 4000 or 6000) g.mol À1 and sodium thiosulfate pentahydrate at different temperatures (293.15e313.15) K and under atmospheric pressure. Correlations of experimental data of binodal curves were carried out using the Merchuk methodology. The effects of temperature, polymer molecular weight and of the nature of the anion of salts on binodal curves were discussed. In comparison with other anions previously investigated, the salting-out ability of the thiosulfate anion was between those of citrate and tartrate anions. Finally, the Othmer-Tobias and Bancroft equations and the NRTL activity coefficient model were used for correlating tie line compositions.

Liquid–Liquid Equilibrium Data of Macromolecule + Ammonium Thiosulfate + Water Ternary Systems at 283.2, 298.2, and 313.2 K

“…As expected, the ATPS with similar global compositions showed higher absolute STL values as the temperature was increased. As highlighted previously and reported elsewhere, ,,,,, the spontaneous transfer of water molecules from the macromolecule phase to the electrolyte phase is responsible for an increase in the absolute STL value. This occurs because, as the temperature increases, there is an increase in the macromolecule concentration in the MRP, concomitantly with a decrease in the electrolyte concentration in the ERP.…”

“…Different electrolytes have been used in the literature to obtain ATPS composed of macromolecules, such as sulfates, − phosphates, , citrates, , thiocyanates, and tartrates. ,,, However, as far as we know, liquid–liquid equilibrium data made up of ammonium thiosulfate are not related in the literature. Two studies reporting the use of sodium thiosulfate to obtain ATPS with PEO with a molar mass of 1500, 4000, or 6000 g mol –1 . , The use of ammonium thiosulfate ((NH 4 ) 2 S 2 O 3 ) as the electrolyte is an excellent strategy for the separation of analytes, mainly metal ions, because, compared to many other salts, it is inexpensive and nontoxic and has reducing and complexing characteristics. In addition, it can be used as an alternative to the leaching of metals such as gold as opposed to cyanide, has a hygroscopic nature, and is soluble in water, which makes this electrolyte an essential alternative in ATPS for analytical purposes. , …”

Liquid-liquid equilibria in aqueous two-phase ethanol/salt systems at different temperatures and their application to anthocyanins extraction

“…ATPS formation was first observed by Beijerinck in 1896, when he mixed aqueous solutions of polymers (starch and gelatin, agar-agar and gelatin) (Oqbal et al, 2016). Studies have then been carried out using different types of polymers, which combined at certain concentrations leading to phase separation (Dliveira et al, 2018). However, only in the 1960s it was reported the potential application of ATPS to recover biomolecules (Albertsson, 1958).…”

“…The use of ATPS has been suggested as an alternative to the conventional methods of extraction and purification of several biomolecules of technological and industrial concern (Shukla et al, 2018), owing to several advantages offered by them, among which are reduced number of separation steps, lower costs and higher purity of recovered products (Dliveira et al, 2018). On addition, phases are constituted mainly by water, which makes the environment milder for biomolecules, preserving and maintaining their biological activity (Asenjo & Andrews, 2011).…”

Aqueous two-phase system (polyethylene glycol + ionic liquid) for extraction of α-amylase: phase diagrams, systems characterization and partition study

“…ATPS are formed by two phases coexisting in equilibrium due to the dissolution, at appropriate concentrations, of solute pairs in water (Freire et al 2012;Wu et al 2017). They are formed by two immiscible or partially miscible aqueous phases which can be obtained by the addition of two aqueous solutions of two natural or synthetic hydrophilic polymers, of a polymer solution and a saline solution, an ionic liquid and a salt or polymer, a surfactant and polymer or salt or a low molecular weight alcohol and a salt (Rodríguez et al 2009;Pereira et al 2013;Liu et al 2015;Hekayati et al 2016;Fan et al 2017; Barani et al 2018;Junqueira et al 2018;Oliveira et al 2018;Escudelo et al 2019;Penido et al 2019).…”