Uranium anion exchange resins

Ion Excha.nge, The recovery of uranium from leach solutions using ion exchange is a very important process (42). The uranium(VI) is selectively adsorbed to an anion-exchange resin as either the anionic sulfato or carbonato complexes. In carbonate solutions, the uranyl species is thought to be the tris carbonato complex, U02(C03) 3 [24646-13-7] and from sulfate solutions the anion is likely to be U02(S0 , where nis ) [56959-61-6] or 2 [27190-85-8], The uranium is eluted from the resin with a salt or acid solution of 1 AfMCl or MNO (M = H", Na", The sulfate solution is... 

The separation of basic precipitates of hydrous Th02 from the lanthanides in monazite sands has been outlined in Fig. 30.1 (p. 1230). These precipitates may then be dissolved in nitric acid and the thorium extracted into tributyl phosphate, (Bu"0)3PO, diluted with kerosene. In the case of Canadian production, the uranium ores are leached with sulfuric acid and the anionic sulfato complex of U preferentially absorbed onto an anion exchange resin. The Th is separated from Fe, A1 and other metals in the liquor by solvent extraction. 

Chloroform extraction of uranium quinoline complex Uranium adsorbed as azide on basic ion exchange column, uranium desorbed with 1 M hydrochloric acid Uranium adsorbed on bismuthol(II) modified anion exchange resin, desorbed with 0.1 M cysteine Uranium, by square wave adsorptive stripping voltammetry... 

There are several uranium ore-bodies in the world that cannot be leached economically with sulfuric acid because of the high limestone content of the ore. Such ore-bodies are generally leached with an alkaline solution of sodium carbonate and bicarbonate. Carbonate also forms anionic complexes with the uranyl ion the predominant species being UC fCC 4- — and may therefore also be treated with anion-exchange resins. 

Uranium U(VI) (also Fe, Co, Cu, Zn, and Cd) in 10 M HC1 solution is present in the form of the complex uranyl anion U02CI42, which is adsorbed on an anion exchange resin.43 44 Separation and purification of uranium from other elements is possible in sulfuric acid solution. When the H2S04 (aq) concentration is >0.01 M, uranium exists in the anionic forms U02(S04)22- and U02(S04)34. In contrast to uranium, other elements (Fe, Co, Cu, Zn, and Cd) do not form anionic complexes in sulfuric acid solution.34... 

Sample treated with HCI and H2O2, clean-up on anion exchange resin column Spectrophotometric (total uranium) 5 pg/L 87% at 11 pg/L Kressin 1984... 

Brits, R. J. N., Smit, M. C. B. Determination of uranium in natural water by preconcentration On anion-exchange resins and delayedneutron counting. Anal. Chem. 49, 67 (1977)... 

The sorption of uranium from acid sulfate leach liquors by strong base anion exchange resins is unusual since complexes of the type [U02(S04) ] " may be sorbed by both ion exchange and addition mechanisms. High concentrations of other species are present in the leach solution due to dissolution of pyritic and siliceous components of the ore, but, apart from iron, they do not interfere with the sorption of uranium as a complex anion. Iron(III) also forms an anionic sulfate complex, but is only weakly held by the resin and is displaced ahead of the uranium. The sorption of uranium may be represented by equations of the type ... 

The anion-adsorption capacity of some commercially available anion-exchange resins is given in Table 5.21. Merritt [M3] uses 1.25 meq/ml resin as a representative number. For uranium adsorbed as quadruply charged 1102(804)3 ", this is equivalent to... 

Protactinium can be recovered from irradiated thorium, after fission-product decontamination, by exchange onto Dowex 1-X8 anion-exchange resin from i9 M HCl solution. Thorium is then eluted with 9 M HCl, followed by elution of Pa(V) with 9 M HC1-0.2S M HF. Uranium is eluted with 0.25 M HF [Kl, K4]. 

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