Partitioning of U, Np, Th, and Eu between acidic aqueous Al(NO3)​3 solutions and various TOPO extraction chromatographic materials

As the Hanford site undergoes remediation, it is noted that significant economies could be realized by minimizing the amt. of aluminum deposited in High-​Level Waste glass. Though such a step is not planned, an acidic scrub of the Hanford sludge could enhance Al removal. It is likely that the resulting Al(NO3)​3 Al(NO3)​3 soln. would contain measurable amts. of transuranic elements, thus the thus the soln. might require some secondary treatment to remove TRU contamination. Thus far, extn. chromatog. (EXC) has shown promise [1] as an alternative to a liq.-​liq. remediation of the Hanford site. Previous EXC studies have shown >99​% of the Eu can be extd. from simulated Al​/Cr waste. This study continues an examn. of a hypothetical secondary cleanup of the waste by studying the removal of UO22+, NpO2+, NpO22+ and Th4+ from using tri-​n-​octyl phospine oxide (TOPO) impregnated XAD7 resins. Neptunium was held in the V and VI oxidn. states using ascorbic acid and chromate, resp. Initial results show extn. following classical metal recovery trends, wherein an increased Zeff correlates with increased distribution of the metal into the org. resin phase. The uptake of Eu3+ (representative of An3+) on a column of the same material was also investigated. Uptake kinetics were improved by wetting the TOPO-​XAD7 resin with n-​dodecane (TOPO-​XAD7n)​. The presence of n-​dodecane also provided consistency between batch mode and column mode metal recovery. Preliminary data show >99​% recovery of metal ions with a Zeff ≥ 3 under various simulated conditions.