Liquid–Liquid Equilibria of Polyvinylpyrrolidone + Several Ammonium Salts + Water Aqueous Two-Phase Systems: Experimental and Correlation

Abstract

Phase equilibrium behaviors of polyvinylpyrrolidone (PVP) + (NH 4 ) 2 HPO 4 , (NH 4 ) 2 SO 4 , (NH 4 ) 2 CO 3 , (NH 4 ) 2 C 4 H 4 O 6 , and (NH 4 ) 2 HC 6 H 5 O 7 + H 2 O aqueous two-phase systems (ATPS's) were determined at 298.15 K. A series of common phase-forming ammonium salts and the corresponding anions were discussed. Meanwhile, the temperature effect on phase equilibrium behavior for PVP (K30) + (NH 4 ) 2 HPO 4 + H 2 O ATPS was investigated at (288.15, 298.15, and 308.15) K. It was found that phase-forming abilities of the salts are in the order: (NH 4 ) 2 HPO 4 > (NH 4 ) 2 SO 4 > (NH 4 ) 2 C 4 H 4 O 6 > (NH 4 ) 2 HC 6 H 5 O 7 > (NH 4 ) 2 CO 3 . Furthermore, a third-order polynomial equation was used to correlate the binodal data, while a simple two-parameter equation along with the Othmer−Tobias and Bancroft equations was used to correlate the tie-lines data. All equations used above were proved to be valid for the experimental data. At last, the data of critical points were obtained by an extrapolation method.

Determination of aqueous two-phase system phase-forming components in the presence of bovine serum albumin

“…The coefficients a 1 and a 2 were independent of polymer molecular weight, which was also reported earlier for other PEG + salt systems [9]. Furthermore, these coefficients were independent of pH.…”

“…Many polymer-salt ATPS have been analyzed by conductivity and refractive index measurements in order to determine the concentration of PEG and salt [1,[6][7][8][9][10][11]. However, the effect of the model protein bovine serum albumin (BSA) on the quantification of the phase-forming components has never been investigated systematically and reported so far.…”

“…% salt, for which linear refractive index calibration curves are obtained [11]. Beyond these concentrations, linearity is not maintained because of the proximity to the two-phase region [9]. Thus, before refractive index measurements, it was necessary to dilute the samples to the above mentioned mass fraction range.…”

Integrated method of thermosensitive triblock copolymer–salt aqueous two phase extraction and dialysis membrane separation for purification of lycium barbarum polysaccharide

“…The effect of L44 concentration was studied at high salt concentration, and the ''free water" in the bottom phase was insufficient for dissolving LBP as discussed above. As the polymer concentration increased, the salt concentration in the bottom phase would increase (Wang et al, 2012). So the ''salting-out effect" was enhanced, leading to the decrease of R L.…”

Liquid–liquid equilibria of ionic liquid 1-butyl-pyridinium tetrafluoroborate and ammonium citrate/trisodium citrate/sodium succinate/sodium acetate aqueous two-phase systems at 303.15K: Experiment and correlation

“…where k, n, k 1 , k 2 and r are the fitting parameters; used for the assessment and correlation of tie-line compositions of polymer-based ATPSs [39], hydrophilic organic solvents-based ATPSs [40] and ionic liquid-based ATPSs [41,42]. A linear dependency of the plots log Table 7 from which we can conclude that Eqs.…”