Process improvements for the separation of plutonium (Pu) and americium (Am) from nuclear waste streams is of pressing importance to reduce activity, dose, and hazard classification of waste and recovery of valuable products. Solvent extraction using liquid:liquid methods of reprocessing acidic and salt-rich aqueous chloride waste streams was evaluated under process-relevant conditions. The quaternary ammonium ionic liquid Aliquat 336^®, which extracts anionic metal-chloride species, was used as the organic extractant. Pu is favored to form anionic species in high hydrochloric acid (HCl) solutions, while Am is not, indicating separation of the two can be achieved.

Distribution ratios, K_D(calculated as K_D = [Me]_org/[Me]_aq, where [Me]_org and [Me]_aq are the final concentrations of metal in organic and aqueous, respectively), were determined through batch extractions using neodymium (Nd) as an Am surrogate and iron (Fe) and uranium (U) as Pu surrogates and likely co-contaminants. The metals were dissolved in a range of HCl and salt eutectic mixtures and contacted with 3 wt % Aliquat 336^® in xylenes. Results thus far (Figure 1) indicate that Aliquat 336^® diluted in xylenes is a promising extractant to provide efficient separation and recovery of Pu from Am in acidic and salt-rich chloride waste streams.

<i>Figure 1 - Distribution ratios (K</i><i>D</i><i>) for Fe and Nd in a range of HCl and salt eutectic mixtures contacted with 3 </i><i>wt</i><i> % Aliquat336</i><i>®</i><i> in xylenes. </i>

Figure 1 - Distribution ratios (KD) for Fe and Nd in a range of HCl and salt eutectic mixtures contacted with 3 wt % Aliquat336® in xylenes.

George Goff

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