Application of crossflow microfiltration to emulsion separation in extraction processes

Abstract

This paper considers the feasibility of using emulsion membrane filtration as a means of recovering dilute organic solutes from aqueous process streams. The process offers a means of enhancing separation rates and reducing separation costs of traditional solvent extraction by capitalising on highly dispersed emulsions, which are subsequently separated by membrane filtration. Phenol, acetic acid and glyoxylic acid have been recovered by this method in the present work using tridecanol as solvent. Suitable selection of other solvents (plus carriers) will generally extend the technique to a wider range of organics. A major weakness of the method of organic solute recovery is that of membrane fouling which results in substantial reductions in fluxrate over the operating period of filtration. This behaviour has been analysed using the concept of a modified fouling index. Preliminary mercury porosimetry data demonstrate the change in membrane surface characteristics resulting from fouling. An initial economic evaluation of the process is used to measure its viability.