Multi-staging for extraction of cesium from nitric acid by a single liquid–liquid countercurrent centrifugal extractor with Taylor vortices

Abstract

Fission products that emit considerable decay heat and radioactivity, such as 137 Cs, have a large impact on waste management. Small and high-performance extractor is desirable for separating such nuclei. In this study, we implemented the continuous extraction of Cs from nitric acid in a single liquid-liquid countercurrent centrifugal extractor with Taylor Vortices by calix [4]arene-bis(t-octylbenzo-crown-6)(BOBCalixC6) as an extractant with trioctylamine(TOA) as a suppressant and with 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-secbutylphenoxy)-2-propanol (Cs-7SB) as a phase modifier. Because of slow extraction kinetics of this process, extraction with multiple theoretical stages by just replacing conventional extractors into the single centrifugal extractor is difficult. Hence, we improved the dispersion of organic phase by an inner rotor made of lipophilic epoxy resin and elevating the solution temperature to lower the viscosity. Higher temperature was not appropriate from the aspect of chemical equilibrium in this process, but extraction with multiple theoretical stages was found to be possible.

Extraction equilibrium and thermodynamics of cesium with a new derivative of calix[4]biscrown

“…Due to the high selectivity for Cs(I)/Na(I), 1,3-alternate calix [4]biscrown-6 has been paid more attention than 1,3-alternate calix [4]monocrown-6 in recent years [16,17]. Processes like fission product extraction [18,19] and caustic-side solvent extraction [20,21] using calix [4]biscrowns to selectively separate cesium from the highly active liquid waste (HLW) have been reported.…”

Microextraction of lanthanum using a rotating microchannel extractor

“…It can be defined as passive mixing. As there are few studies on active mixing micro-extractors, inspired by Nakase et al, 17,18 our research lab designed a rotating microchannel extractor.…”

Transport Modeling of Kinetically Limited Microscale Extraction Systems: Droplet and Supported Liquid Membrane Separations

“…Unlike conventional liquid–liquid extraction separations, in which an organic and aqueous phase are agitated to form a short-lived emulsion approaching an equilibrium composition, transport of components from an aqueous feed to an aqueous strip through an organic liquid membrane is defined by the chemical potential gradient between the two aqueous phases . The development of highly selective solvent extraction systems is often plagued by difficulties in implementation due to slow phase transfer kinetics. − Quantification of phase transfer rates for these types of kinetically limited systems allows the performance of different ligands to be compared and can be used to determine if the rate of phase transfer is fast enough for a given supported liquid membrane (SLM) or solvent extraction separation.…”