Mutual separation of strontium, cerium, and uranium using pressure-driven flow in 100 nm-sized nanofluidic channels

We developed a novel nanofluidic control device, and demonstrated mutual separation of various metal ions in 300–3000 nm-sized nanofluidic channels. The ion concentration ratios of Sr(II), Ce(III), and U(VI) in solutions before and after nanofluidic separation treatments were measured using ICP analysis. The results showed that the mass flow rates of Sr(II), Ce(III), and U(VI) ions in nanofluidic channels were quite different. The flow rates of Ce(III) and U(VI) ions in solutions through 3000 nm-sized nanochannnels were much smaller than those of Sr(II), and increased gradually with decreasing space sizes until 300 nm. The decontamination factors of Sr(II) and Ce(III) against U(VI) were determined as 10.6 and 12.5 in 3000 nm-sized channels and 1.3 and 1.7 in 300 nm-sized channels, respectively. The ion concentration ratios of Ce(III) and U(VI) in acid solutions were also examined in 300 nm-sized channels, and the mass flow rates of Ce(III) and U(VI) were found to decrease and increase with increasing acid concentrations, respectively. Furthermore, the nanofluidic device made it possible to mutually separate U(IV) and U(VI) ions in acid solutions by flowing into nanofluidic channels.

► We develop a novel nanofluidic-based separation concept.
► We realize mutual separation of strontium, cerium, and uranium in 100 nm-sized nanofluidic channels under pressure-driven flows.
► The mass flow rates of these ions in the nanofluidic channels change depending on the variation of channel sizes and acid concentrations.
► This technique makes it possible to separate mutually even same ion species invoking uranium(IV) and uranium(VI) by only flowing into the nanofluidic channels.