RESUMO
A new liquid-liquid extraction method, called the "emulsion flow" method, is expected to realize an ideal liquid-liquid extraction by controlling the emulsion generation and separation using liquid spraying, only by solution sending. In order to understand the mechanism of emulsion control in the emulsion flow method, the size distribution of droplets in two liquid-phase mixtures was compared by using originally designed apparatuses 1) for the case of liquid spraying and 2) for the case of mechanical stirring. We demonstrated that the size distribution of droplets generated near a mixing device (a nozzle for liquid spraying or an impeller head for mechanical stirring) determines the phase-separation property.
RESUMO
A previously reported emulsion flow (EF) extraction system does not equip the refining device for any used organic phase. Therefore, the processing of large quantities of wastewater by using the EF extractor alone could lead to the accumulation of extracted components into the organic phase, and a lowering of the extraction performance. In the present study, we developed an organic phase-refining-type EF system, which is equipped with a column for refining a used organic phase to prevent accumulation, and successfully applied it for treating uranium-containing wastewater.
RESUMO
A single current "emulsion flow" liquid-liquid extraction apparatus has a head with a number of holes from which micrometer-sized droplets of an aqueous phase spout into an organic phase to mix the two liquid phases. For practical use, however, a fatal problem can occur when particulate components in the aqueous phase plug the holes. In the present study, we have succeeded in solving the problem by applying a counter current-type emulsion flow extractor where micrometer-sized droplets of the organic phase are generated.
RESUMO
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 HNO(3) 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.
RESUMO
In order to monitor a radioactive nuclide of strontium-90 in seawater around nuclear facilities, a solvent-extraction method for collecting Sr(II) in seawater was examined. A reversed-micellar extraction system containing an anionic surfactant AOT and a molecular extractant N,N,N',N'-tetra(n-octyl)diglycolamide (TODGA) in n-hexane was chosen for the extraction of Sr(II) from model solutions of seawater containing 0.5 M NaCl (1 M = 1 mol dm(-3)), 0.05 M MgCl(2), and/or 0.01 M CaCl(2). The combination of AOT-forming reversed micelles and TODGA coordinating with Sr(II) as an organic ligand (extractant) was found to be efficient for the extraction of Sr(II) from model solutions. The mechanism of the reversed-micellar extraction system was also considered in the present study.