Emulsification processes: on-line study by multiple light scattering measurements.

The use of ultrasound in various processes of the chemical industry has been a subject of research and development for many years. As regards in emulsification, apart from formulation variables, power is the most important parameter. Efficiency of emulsification processes may be followed and evaluated by measuring particle size distribution, which mainly governs the kinetic stability of such dispersions. Unfortunately, this kind of measurement must be performed at high dilution (low volume fraction of dispersed phase). The present work is devoted to the on-line study of ultrasound emulsification by means of a newly developed apparatus based on multiple light scattering, which allows us to determine average droplet diameter and its variations directly on concentrated media. The model system was an oil (kerosene)-in-water emulsion stabilized by a polyethoxylated sorbitan monostearate.

Emulsification by ultrasound: drop size distribution and stability.

The aim of this work is to compare the oil-in-water emulsions produced by mechanical agitation (Ultra-Turrax, 10,000 rpm, P = 170 W) or power ultrasound (ultrasound horn, 20 kHz, 130 W) using the same model system: water/kerosene/polyethoxylated (20 EO) sorbitan monostearate. The following parameters were varied: emulsification time, surfactant concentration, consumed power and volume fraction of oil. With ultrasound, the drop size (Sauter diameter, d32) is much smaller than that given by mechanical agitation under the same conditions, which makes insonated emulsions more stable. For a given drop size (d32), less surfactant is required.