Abstract
Ethanol was separated from the aqueous solutions through ultrasonic atomization. Ethanol enrichment was evaluated by determining ethanol concentration in condensates collected from atomized mist and vapor. The amount of collected mist and vapor accorded with the amount of liquid left form the atomization column. In the limited range of ethanol feed concentration below 30 mol%, ethanol concentration in the condensates was affected by ultrasonic parameters such as frequency and input power. Ethanol enrichment was enhanced at higher frequencies and lower input power. The effect of ultrasonic parameters on ethanol enrichment was interpreted from a viewpoint of cavitation. Potassium iodide oxidation was conducted to examine the occurrence of cavitation, and the number of violently collapsing bubbles. The use of higher frequency and lower input power, which corresponded to enhance ethanol enrichment, resulted in a decrease of KI reactivity. This trend suggests that violently collapsing bubbles enhanced fragmentation of bulk liquid where no separation mechanism works. Assuming that the surface excess of ethanol plays a significant role in the separation, possible routes of ethanol transfer from liquid to mist or vapor are suggested.
