Influence of the Molecular Weight of PEG on the Polymer/Salt Phase Diagrams of Aqueous Two-Phase Systems

Abstract

Binodal data for systems composed by polyethylene glycol (PEG) (4000, 6000, or 8000) and salt (potassium citrate, potassium sodium tartrate) were obtained using the cloud point method, at T = 298.15 K. Merchuk equation was applied for the fitting of binodal curves. Tie-lines for systems of PEG (4000, 6000)–potassium citrate and PEG (4000, 6000, 8000)–potassium sodium tartrate were determined by electrical conductivity and lyophilization, and correlated using Othmer–Tobias and Bancroft equations, to verify the reliability of the measured tie-lines. Data were compared with that of previous studies reported in the literature, giving an indication of which system is more efficient in terms of separation, taking into account possible combinations of salt’s cations and PEGs of different molecular weight chosen for ATPS.

Extraction of glycyrrhizic acid by aqueous two-phase system formed by PEG and two environmentally friendly organic acid salts - sodium citrate and sodium tartrate

“…For both systems, PEG of higher molecular weight produces larger heterogeneous region. This is already confirmed by many previous studies [27,28,30]. It is evident that ATPS formed by sodium tartrate has larger STL than sodium citrate.…”

“…Taking advantage of these clean ATPS's, this paper utilizes ATPS formed by PEG-sodium citrate and PEG-sodium tartrate to extract GA from its stock solution, to investigate the feasibility of extracting GA by using these two ATPS's. These two ATPS's are selected because they are found having quite large heterogeneous region and thus good separation capability [27,28].…”

Opposite Effects Induced by Cholinium-Based Ionic Liquid Electrolytes in the Formation of Aqueous Biphasic Systems Comprising Polyethylene Glycol and Sodium Polyacrylate

“…For all PEG-NaPA systems investigated, the biphasic region increases with the MW of PEG, meaning that lower amounts of phase-forming components are required to undergo liquid-liquid demixing when employing higher MW PEG polymers. The same trend has been reported for other ABS composed of PEG-polymer, [29] PEGsalt [30,31] and PEG-IL [32][33][34].…”

Liquid–liquid phase separation in aqueous solutions of poly(ethylene glycol) methacrylate homopolymers

“…As previously mentioned, LLPS has been well‐reported in aqueous solutions of PEG and salts 3,14–17 . This has been either thermally‐induced, that is, by increasing the temperature, or salt‐induced, that is, by increasing the salt concentration at room temperature.…”