Representation of liquid-liquid equilibria for polymer-salt aqueous two-phase systems

abstract

In this work the modified Wilson equation, proposed in a previous publication, for aqueous binary polymer solutions is extended to calculate liquid-liquid equilibrium of aqueous two-phase systems containing one salt with either polyethylene glycol or ethylene oxide-propylene oxide random copolymer. The Debye-Huckel equation based on the Fowler-Guggenheim theory is used to represent the long-range electrostatic interactions of ions. The parameters are estimated from only one or two tie-lines and are used to predict the phase diagrams with different molecular weights and polymer-salt systems at different temperatures. The predictions obtained with the modified Wilson equation are in good agreement with the experimental data. (C) 2004 Elsevier Ltd. All rights reserved.

keywords

EXCESS GIBBS ENERGY; LOCAL COMPOSITION MODEL; POLYETHYLENE-GLYCOL; AMMONIUM-SULFATE; ETHYLENE-OXIDE; THERMODYNAMIC PROPERTIES; POLY(ETHYLENE GLYCOL); ELECTROLYTE SYSTEMS; RANDOM COPOLYMER; PHASE-DIAGRAMS

subject category

Engineering

authors

Xu, X; Madeira, PP; Macedo, EA

our authors

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