Abstract
In this study, both the antisolvent sonocrystallization process of sodium chloride and cavitation activity were investigated as a function of frequency (22–1080 kHz) and acoustic calorimetric power (0–30 W). For frequencies between 20 and 139 kHz, the size of the sodium chloride crystals decreased sharply with increasing power. For frequencies 647 and 1080 kHz, a certain power threshold needs to be exceeded before a decrease in the crystal size was observed. This power threshold coincided with the power threshold for sonoluminescence emission from cavitation bubbles. It was found that the onset of cavitation bubble activity, irrespective of the magnitude (measured in terms of sonoluminescence), enhanced the crystal nucleation rate and decreased crystal size. The minimum crystal size obtained was found to decrease with increasing maximum total integrated sonoluminescence intensity. The results suggest sonoluminescence could be used as a measure to evaluate the sonocrystallization process and that a greater collapse intensity would yield the smallest crystals. In addition, photographs of the sonocrystallization process are reported, suggesting a link between nonsymmetrical transient cavitation activity and crystal nucleation.