Acoustic field assisted demixing of aqueous two-phase systems

Acoustic field assisted demixing was employed to decrease the demixing time in aqueous two-phase systems (polyethylene glycol-maltodextrin and polyethylene glycol-potassium phosphate). Application of acoustic field has decreased the demixing time in polyethylene glycol-maltodextrin by around twofold and up to about 3.2-fold in polyethylene glycol-potassium phosphate systems. Ultrasonication has induced mild circulation currents in the phase dispersion, which has enhanced the rate of droplet coalescence, eventually resulting in decreased demixing time. In the polyethylene glycol-maltodextrin system, phase demixing was found to depend greatly on which of the phases is continuous and viscosity of the continuous phase was observed to have a strong influence on the movement of the droplets and hence controlling the phase demixing rate. In case of the polyethylene glycol-potassium phosphate system, droplet coalescence was found to play a critical role in phase demixing. Addition of NaCl increased the demixing time and presence of Escherichia coli cells did not seem to have any influence on phase demixing. (C) 2002 Elsevier Science B.V. All rights reserved.