New Apparatus for Liquid–Liquid Extraction, “Emulsion Flow” Extractor

A simple and low-cost apparatus for continuous and efficient liquid–liquid extraction, which does not need continual mechanical forces (stirring, shaking, etc.) other than solution sending, has newly been developed. This apparatus, named “emulsion flow” extractor, is composed of a column part where an emulsified state fluid flow (emulsion flow) is generated by spraying micrometer-sized droplets of an aqueous phase into an organic phase and a phase-separating part where the emulsion flow is destabilized by means of a sudden decrease in its vertical liner velocity due to a drastic increase in cross-section area of the emulsion flow passing through. In the present study, the performance of a desktop emulsion flow extractor in the extraction of Yb(III) and U(VI) from aqueous HNO3 solutions into isooctane containing bis(2-ethylhexyl) phosphoric acid (D2EHPA) was evaluated. The mixing efficiency of the emulsion flow extractor was found to be comparable with that of a popular liquid–liquid extractor, mixer-settler. Moreover, the emulsion flow extractor proved to have an overwhelming advantage in terms of phase-separating ability.