A modified Wilson model for the calculation of vapour+liquid equilibrium of aqueous polymer+salt solutions

Aqueous two-phase systems of poly(vinylpyrrolidone) and potassium citrate at different temperatures—Experimental results and modeling of liquid–liquid equilibrium data

“…In our previous work [22], we extended the Wilson model to represent the excess Gibbs energy of polymer-electrolyte solutions. The extended Wilson model was used for correlation of water activity data of some aqueous polymer-salt systems [22].…”

“…The extended Wilson model was used for correlation of water activity data of some aqueous polymer-salt systems [22]. In this study, the extended Wilson model is applied to correlation of liquid-liquid equilibrium data of the investigated aqueous two-phase systems.…”

“…In our previous work [22] the Wilson model was extended to express the short-range interaction for salt-containing polymer solutions, by applying the local composition concept to the individual segments, ions and solvent molecule, rather than polymer, salt and solvent and by incorporating the two assumptions of local electroneutrality and like-ion repulsion proposed by Chen [36] and Chen and Evans [37]. For an aqueous polymer-salt system, the extended Wilson equation for the short-range interaction contributions to the excess Gibbs energy is given by [22]:…”

“…Recently, the Wilson model [21] was extended to represent the excess Gibbs energy of aqueous polymer-electrolyte solutions [22]. This model has three contributions.…”

“…The Pitzer-Debye-Huchel model is used for longrange electrostatic interactions between ions and the modified Wilson equation is used for short-range interactions between all species. This extended model successfully was used to correlate the vapor-liquid equilibrium data of several polymer-salt-water systems [22]. In the present work, a simple modification has been done on this model and then used to correlate the experimental LLE data of investigated aqueous two-phase systems.…”