Performance and Characteristics of Liquid-Liquid Extractor with Ultrasonic Irradiation

Abstract

A liquid-liquid extractor equipped with 25 kHz ultrasonic horn through which feed (methyl-isobutyl ketone (MIBK), dissolved with butyric acid) can be dispersed into solvent (water) was newly developed and its performance and characteristics were investigated experimentally. The extraction rate in this extractor was remarkably enhanced because the interfacial contact area between feed droplets and solvent is conspicuously increased by emulsification with ultrasonic irradiation.
The effects of residence time in the extractor, volumetric fraction of feed and input power of the ultrasonic generator on the capacity coefficient were experimentally investigated by use of MIBK-butyric acid-water as a sample, and an experimental equation representing the correlation between the capacity coefficient and these factors was proposed.
Results showed that the capacity coefficient was about forty times that of the usual perforated-plate extraction tower for the same system. The over-all mass transfer coefficient, K_R, was calculated with the capacity coefficient and the interfacial contact area, which was obtained from the drop size distribution measured by a photomicrograph. It was seen that K_R obtained is slightly smaller than that of usual extractors and the conspicuous increase in the extraction rate depends mainly on the increase in the interfacial contact area. Furthermore, mass transfer from feed droplets to solvent was analyzed theoretically by assuming that a feed droplet is surrounded by a concentric spherical shell of solvent and that mass transfer by diffusion occurs in unsteady state, and the theoretical result was compared with the experimental ones.