Ultrasonic-assisted emulsification process in micro-packed bed reactor and its application on nano-emulsion preparation

Abstract

To extend the flow rate range in ultrasonic microreactors and enhance its emulsification efficiency, a strategy by filling solid packing into microchannel was adopted. The flow behavior of cavitation bubbles in the novel reactor was first investigated, finding that solid packing can effectively capture bubbles, even at relatively high liquid throughput. Additionally, the filled packing demonstrates superior energy-concentrated effect. Subsequently, the cavitation-induced emulsification process within the packing region was analyzed. The liquid phase was emulsified in less than 1 s, demonstrating the high effectiveness of this combined strategy. Finally, the micro-packed bed ultrasonic microreactor was applied to produce Vitamin E-enriched nano-emulsion. Without packing addition, a plateau region in emulsion size was observed due to the competition between droplet disruption and coalescence. By adding solid packing, the plateau was eliminated and emulsion size was significantly reduced to 156.0 nm with merely 1/3 of energy input and 1/5 of surfactant addition.