Aqueous Two-Phase Systems of Poly(vinyl pyrrolidone) and Sodium Sulfate:  Experimental Results and Correlation/Prediction

Abstract

New experimental liquid-liquid-phase equilibrium data are reported for aqueous systems containing poly(vinyl pyrrolidone)sof different molecular masssand sodium sulfate at (298 and 338) K together with parameters for a semiempirical model for the excess Gibbs energy which is used to describe the experimental data.

Aqueous two-phase systems containing N-vinylpyrrolidone: Experimental results and correlation/prediction

“…That change is very similar to the decrease observed in the ternary systems (PVPxy + Na 2 SO 4 + H 2 O) that were investigated previously [5]. …”

“…However, the feed was a ternary mixture of (NVP + PVPxy + H 2 O) with even mass fractions of NVP and PVPxy and the titrants were aqueous solutions of sodium sulfate. Furthermore, the compositions of the coexisting liquid phases were determined experimentally for the ternary as well as for the quaternary systems at 25 • C. A detailed description of the experimental procedures has been given before [5]. Therefore, only some essential features are repeated here.…”

“…As in a previous work [5] the VERS-model of Großmann et al [6] is applied to describe the new experimental results. The VERSmodel is an extension/modification of Pitzer's equation [7] for the excess Gibbs energy of aqueous electrolyte solutions.…”

“…The equations for the activity coefficient of a solute species and the activity of the solvent have been given in previous publications (cf. [5]). The following information is required for the systems of interest in the present work: Table 3 Experimental results for the composition of (NVP (1) + PVPxy (2) + Na2SO4 (3) + H2O (4) Table 4 Experimental results for the liquid-liquid equilibrium of (NVP (1) + Na2SO4 (2) + H2O (3) Table 5 Experimental results for the liquid-liquid equilibrium of (NVP (1) + PVP17 (2) + Na2SO4 (3) + H2O (4) Table 6 Experimental results for the liquid-liquid equilibrium of (NVP (1) + PVP30 (2) + Na2SO4 (3) + H2O (4) -The number of monomers of a PVPxy polymer.…”

“…In a previous publication [5], we presented experimental and correlation (from the VERS model) results for the liquid-liquid equilibrium of aqueous two-phase systems of poly(vinylpyrrolidone) (PVP) and sodium sulfate at 25 and 65 • C. In the present investigation the research was extended to liquid mixtures that also contain the monomer N-vinylpyrrolidone.…”