Separation of actinide ions from radioactive waste solutions using extraction chromatography

Americium, plutonium, and uranium ions were successfully removed from acidic waste solutions using several types of extraction chromatographic resins. These resins might be applied to convert the bulk of transuranic (TRU) wastes, which contain actinides, to low-level radioactive wastes. Because disposal of low-level wastes is much less expensive than TRU wastes, economic incentives exist for actinide removal. Both batch equilibrium extraction measurements and column elution measurements were used to evaluate the effectiveness of the resins for actinide removal. Resins containing adsorbed octyl (phenyl)-N,N-diisobutylcarbamoylmethlyphosphine oxide (CMPO) were the most effective in removing americium from the solutions. Plutonium and uranium were more readily extracted than americium. Higher acid concentrations lowered actinide extraction by the resins due to competition between HNO3 and actinide nitrates for the extractant. As expected, high nitrate concentrations improved extraction. Iron (a major component of much TRU wastes) lowered americium extraction due to competition for the extractant. Column extraction measurements showed that actinide extraction by the resins is rapid. Near equilibrium conditions exist in the columns at useful flow rates