Dioxouranium(VI) extraction in microchannels using ionic liquids

The extraction of uranium(VI) from aqueous nitric acid solutions by tributylphosphate {TBP; 30%(v/v)} dissolved in the ionic liquid 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl}amide was investigated. The experiments were performed in a Teflon microchannel of 0.5 mm internal diameter, while the dioxouranium(VI) concentrations in the aqueous and the ionic liquid phases were determined by UV–Vis spectroscopy. The effects of initial nitric acid concentration (0.01–3 M), residence time, and phase flow rate ratio were studied. It was found that, with increasing nitric acid concentration, the percentage of dioxouranium(VI) extracted decreased and then increased again, while the extraction efficiency followed a slightly different trend. Overall mass transfer coefficients varied between 0.049 s−1 and 0.312 s−1.

► Continuous extraction of uranium(VI) from nitric acid solutions in microchannels by using ionic liquids.
► Mass transfer coefficients in the microchannel system during segmented flow.
► The effects of nitric acid concentration on the extraction efficiency.