Effect of Temperature on the Aqueous Two-Phase System Containing Poly(ethylene glycol) Dimethyl Ether 2000 and Dipotassium Oxalate

Abstract

Liquid−liquid equilibria (LLE) of the poly(ethylene glycol) dimethyl ether 2000 (PEGDME2000) + dipotassium oxalate + H 2 O system have been determined experimentally at T = (298.15, 303.15, 308.15, and 318.15) K. The effect of temperature on the binodal curves and tie-lines has also been studied. The Graber et al., Merchuk, and empirical equations were used to correlate the binodal data of this system with the temperature dependence expressed in the linear form with (T − T 0 ) K as a variable. Furthermore, we used the Othmer−Tobias and Bancroft and a temperature-dependent Setschenow-type equation for the correlation and prediction of the liquid−liquid phase behavior of the studied system. The effective excluded volume (EEV) values obtained from the binodal model for this system and other aqueous PEGDME2000−salt systems were determined, and the relation between these values and salting-out ability of different salts was discussed. Also, the effects of type of the polymers PEGDME2000 and PEG2000 on LLE are discussed. Finally, the free energies of cloud points for this system were calculated. According to the results it was concluded that the increase of the entropy is a driving force for the formation of the studied aqueous two-phase system (ATPS).

Extraction in cholinium-based magnetic ionic liquid aqueous two-phase system for the determination of berberine hydrochloride in Rhizoma coptidis

“…[41][42][43] Furthermore, there is also evidence that increasing entropy is the driving force for the two-phase formation. 44 For these salting-out inducing ions (also known as kosmotropes), the increase in the entropy of hydration (D hyd S) can result in the dehydration of the solute and the increase in the surface tension. [45][46][47] The absolute values of D hyd G and D hyd S for anions are in the order of PO 4 48 The abovereported results are in accordance with the order of the saltingout ability of anions.…”

“… 41–43 Furthermore, there is also evidence that increasing entropy is the driving force for the two-phase formation. 44 For these salting-out inducing ions (also known as kosmotropes), the increase in the entropy of hydration (Δ hyd S ) can result in the dehydration of the solute and the increase in the surface tension. 45–47 The absolute values of Δ hyd G and Δ hyd S for anions are in the order of PO 4 3− (Δ hyd G = −2765 kJ mol −1 , Δ hyd S = −421 J K −1 mol −1 ) > HPO 4 2− (Δ hyd G = −1789 kJ mol −1 , Δ hyd S = −272 J K −1 mol −1 ) > CO 3 2− (Δ hyd G = −1315 kJ mol −1 , Δ hyd S = −245 J K −1 mol −1 ).…”

An aqueous two-phase system to pre-purify a heterologously produced siderophore

“…Th ese changes are refl ected in the slope and length of equilibrium tie-lines 11 . Figure 2b indicates that raising the temperature to 30°C increases Ybt accumulation in the upper phase.…”

Temperature Effect on the Liquid–Liquid Equilibrium of Isopropanol + Trisodium Citrate + Water Aqueous Two-Phase Systems at T = 288.15, 298.15, 308.15, and 318.15 K

“…17−20 Although most of these models are not temperature dependent, modification of the parameters of the model as function of temperature is an appropriate approach to include the temperature effect in such models, and in most cases, the parameters of the applied models were modified as a linear or nonlinear function of the temperature, i.e., P = P 0 + P 1 f(T), where P is the original parameter, P 0 and P 1 are new parameters, and f(T) is a function of temperature. 21 Different types of the activity coefficient models, 22−25 in which the activity coefficients of compounds were described as a function of the concentration, have also been developed during past decades and used in the modeling of ATPSs. From these models, the Wilson model 26 is a successful activity coefficient model, which was extended by Sadeghi 27 to use in the correlation and prediction of the activity coefficients of aqueous polymer + salt solutions.…”