Acoustic demixing of aqueous two-phase systems

Aqueous two-phase systems demix slowly due to similar physical properties. This is one of the major drawbacks for their adaptation for industrial scale extraction of enzymes. In the present work, a method to accelerate the demixing rates of these systems, employing a traveling acoustic wave field is reported for the first time. Phase-demixing for three systems, viz. polyethylene glycol (PEG)/sodium sulfate, PEG/potassium phosphate and PEG/maltodextrin were studied. The acoustically assisted process decreased the demixing time significantly (about 2- to 3-fold in PEG/salt systems and about 2-fold in the PEG/maltodextrin system), compared to that in gravity alone. Ultrasonication apparently enhanced the coalescence of the dispersed phase droplets due to the mild circulation currents it caused in the dispersion. This in turn enhanced the rate of demixing due to the increased migration velocity of the larger droplets.