Influence of Molecular Weight of the Polymer on the Liquid−Liquid Equilibrium of the Poly(ethylene glycol) + NaNO₃ + H₂O System at 298.15 K

Abstract

Liquid−liquid equilibria for the poly(ethylene glycol) (PEG) + NaNO3 + H2O system, with PEG of molecular weights 2000, 6000, and 10 000, have been measured at 298.15 K. The binodal curve was fitted using a three-parameter equation, and the compositions of the tie lines at equilibrium were fitted using the Othmer−Tobias equation. These equations were used to develop a mathematical model for interpretation of the equilibrium data of these aqueous two-phase systems (ATPS's). Data on the densities and refractive indexes are also given for the solutions at equilibrium. It was found that an increase in the molecular weight of the PEG produced a displacement of the binodal curve toward the origin and increased the liquid−liquid biphasic zone. The ATPS's studied may be used in separation of iodine and other compounds.

(Liquid+liquid) equilibrium of (NaNO3+PEG 4000+H2O) ternary system at different temperatures

“…The experimental data for each of the curves binodals are shown in tables 1 and 2. The binodal curves of this system at three temperatures (included the binodal curve at T = 298.15 K [5,6]) are presented in figure 1. The effect of temperature on the binodal curves is also appreciated in figure 1 and the tie-lines data are given in tables 3 and 4, additionally are reported densities, refractive indices and absolute viscosities data of each one of these.…”

“…Graber et al [5,6] reported the phase diagram of the (NaNO 3 + PEG 4000 + H 2 O) system at T = 298.15 K and in a later article the influence of molecular weight of the polymer on the LLE also at T = 298.15 K was studied. As far as we know, there is no report on the phase diagram of this system at T = (288.…”

“…In the present work the Chen-NRTL [24], modified Wilson [25] and extended UNIQUAC [23] models were applied for the correlation of experimental LLE data of the (aqueous NaNO 3 + PEG 4000 + H 2 O) system. In this correlation, the experimental data reported by Graber et al [5,6] have also been included. The FloryHuggins expression [26] and Pitzer-Debye-Hückel equation [27] were used for the entropy of mixing molecules of different sizes and to account for the long-range electrostatic interactions of the ions, respectively.…”

Cloud-point measurements of the {H2O+poly(ethylene glycol)+NaNO3} system

“…With respect to the polymers, many of these are used in the making up ATPS such as dextran [1], hydroxypropyl starch [2], poly(N-isopropylacrylamide) [3], and poly(vinylpyrrolidone) [4]. One of the major polymers used for this purpose is polyethylene glycol (PEG), which is a nontoxic, noninflammable and low in cost [5]. The first report in the literature was in 1896 by Beijerinck [6], later Albertsson applied the ATPS for recovery of biomolecules [1], and for several years these systems have been used with this purpose, i.e.…”

Cloud-point measurement for (sulphate salts+polyethylene glycol 15000+water) systems by the particle counting method

“…Many polymers are used in the making up ATPS such as dextran [1], hydroxypropyl starch [2], poly(N-isopropylacrylamide) [3], and poly(vinylpyrrolidone) [4]. One of the major polymers for this purpose is polyethylene glycol (PEG), which is a nontoxic, inflammable and low in cost [5]. For the first time, ATPS were reported when a mixture of gelatine and starch could form two phases and later Albertsson and co-workers studied the ATPS and developed several applications in the field of separation [6].…”