Influence of hydrostatic pressure and gas content on continuous ultrasoundemulsification

Ultrasound is one means among others of producing emulsions mechanically. D roplet disruption in sonicated liquid-liquid systems is considered to be co ntrolled by cavitation. Both hydrostatic pressure and gas content of the li quids influence the probability and intensity of cavitation. Continuous ult rasound emulsification experiments were carried out to elucidate the effect of these parameters on the result of droplet disruption. Maximum energy de nsity in the apparatus decreases with increasing hydrostatic pressure, prob ably due to partial suppression of cavitation which is the main mechanism o f power dissipation. At constant energy density there is no significant inf luence of hydrostatic pressure on the emulsification result, however. Corre sponding results were obtained for the influence of the gas content. Gas sa turation or partial degassing prior to emulsification lead to a shift in ma ximum energy density. But, again, at constant energy density no clear effec t on the droplet size of the emulsion is observed. (C) 2001 Elsevier Scienc e B.V. All rights reserved.