Development of Sorbers for the Recovery of Uranium from Seawater. Part 2. The Accumulation of Uranium from Seawater by Resins Containing Amidoxime and Imidoxime Functional Groups

Abstract

Hydroxylamine derivatives of cross-linked poly(acrylonitriles), so-called poly(acrylamidoxime) resins, are suitable for the accumulation of uranium from natural seawater of pH = 8.1–8.3. Depending on the method of manufacture, these sorbers yield excellent uranium loadings up to some thousand ppm which roughly equals the average uranium content of actually explored uranium ores. The rate of uranium uptake, which is 5-30 ppm/d at room temperature, increases with increasing temperature of seawater. Uranium can be eluted by 1 M HCl with an elution efficiency of more than 90%. Owing to a certain instability of the uranium binding groups in acid eluants, the uranium uptake decreases with increasing number of sorption-elution cycles. Hydroxylamine derivatives of poly(acrylonitrile) are shown to contain simultaneously at least two kinds of functional groups: open-chain amidoxime groups which are stable and cyclic imidoxime groups which are unstable in 1 M HCl. Experimental evidence is presented that the uptake of uranium from natural seawater is closely related to the presence of cyclic imidoxime configurations in the poly acrylic lattice. Polystyrene and poly(glycidylmethacrylate)-based amidoxime and imide dioxime resins are less effective in extracting uranium from natural seawater.