Liquid-Liquid Equilibria Determination and Modeling of ATPS Based on PEG4000 and PVP29000 at 298.15 K and 0.1 MPa

Abstract

Additionally to the known nontoxicity and eco-friendliness of aqueous two-phase systems (ATPS), polymeric ATPS, which are composed of at least one polymer [e.g., poly(ethylene glycol) or poly(vinylpyrrolidone)], provide extractive media with enhanced potential for drug delivery and biomolecule extraction. Nevertheless, the lack of liquid-liquid equilibria (LLE) data concerning these systems still limits their large-scale application and hampers proper thermodynamic modeling, delaying advancements in the design of novel materials and processes based on polymers. In this work, the LLE, i.e., solubility curves and tie-line compositions, of the ATPS {PEG4000 (1) + NaFormate (2) + Water (3)} and {PVP29000 (1) + NaFormate or Na(2)Tartrate or K(2)Tartrate (2) + Water (3)} were determined at 298.15 K and 0.1 MPa. The estimation of tie-line composition using third-degree polynomials of liquid density (rho) and electrical conductivity (kappa) allowed to better understand the influence of composition on these thermophysical properties, and the tie-line data were successfully correlated using the models of Othmer-Tobias and Bancroft-Hubard, achieving determination coefficients (R-2) larger than 0.9575 and 0.9676, respectively. Moreover, the obtained compositions were effectively described using the UNIversal QUAsi-Chemical (UNIQUAC) model, with standard deviations (sigma) lower than 6.84 x 10(-3).