The Discrimination of the Oxidation States of Neptunium in Sodium Hydroxide Solutions by Means of Chromatography on Alumina

A method of discriminating the oxidation states of Np in a NaOH solution by means of chromatography on alumina is proposed. In a NaOH solution of 0.5–1.7 M(1 M=1 mol dm−3), the separation of Np(VI) from Np(VII) can be made effectively by means of chromatography on alumina. Only a little Np(VI) is adsorbed on alumina the Np(VII) adsorbed to some extent, and the Np(V), strongly, under the same conditions. By applying this chromatographic method, the method of preparing Np(VI) and Np(VII) of a tracer quantity in 1 M NaOH is established.