Abstract
ABSTRACT ABEC™-5000, an aqueous biphasic extraction chromatography resin consisting of monomethylated polyethylene glycol (PEG)-5000 covalently bound to a polystyrene support, was investigated for its ability to remove pertechnetate from simulated Hanford tank wastes. Retention of TcO4 − on the resin in batch mode from 2 and 4 M NaOH and from the waste simulants NCAW, SY-101, and SST, indicated that pertechnetate can be selectively removed from these solutions. Column studies were conducted with 4 M NaOH and the NCAW simulant spiked with Na99mmTcO4 or Na95mMmTcO4. The columns can be easily stripped using water, thus concentrating the pertechnetate. The effects of several matrix ions present in the Hanford tanks were investigated. It was found that nitrite and nitrate lower the retention of TcO4 −, while citrate, carbonate, and aluminate enhance the retention. It was also observed that raising the temperature from 25 °C to 40 °C has little effect on retention. Radiation stability studies indicate that ABEC-5000 can still effectively remove pertechnetate after 131 MRads of 60Co exposure.
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