Emulsification by ultrasound: drop size distribution and stability

The aim of this work is to compare the oil-in-water emulsions produced by m echanical agitation (UItra-Turrax, 10 000 rpm, P = 170 W) or power ultrasou nd (ultrasound horn, 20 kHz, 130 W) using the same model system : water/ker osene/polyethoxylated (20 EO) sorbitan monostearate. The following paramete rs were varied : emulsification time, surfactant concentration, consumed po wer and volume fraction of oil. With ultrasound, the drop size (Sauter diam eter, d(32)) is much smaller than that given by mechanical agitation under the same conditions, which makes insonated emulsions more stable. For a giv en drop size (d(32)), less surfactant is required. (C) 1999 Elsevier Scienc e B.V. All rights reserved.