Liquid–liquid equilibrium of aqueous two-phase system (PEG 2000-Sodium Citrate–Water) using potential difference as a key tool

Abstract

The present work involves an attempt to demonstrate the application of potential difference, existing across the interface of the aqueous two-phase system (ATPS), as a tool for the prediction of the phase equilibrium. The contribution due to long-range interaction for the potential difference and its variation with the composition is studied for the polyethylene glycol (PEG) 2000-Sodium Citrate–Water-based ATPS (Merck, Germany). The developed correlation for the potential difference with concentration shows a satisfactory prediction of the phase equilibrium for the present system.

Keywords:

• liquid–liquid equilibria
• aqueous two-phase system
• electrostatic potential difference