Low-level liquid waste decontamination by ion exchange

Improved processes are being developed to treat contaminated liquid wastes that have been and continue to be generated at Oak Ridge National Laboratory. Both inorganic and organic ion-exchange methods have given promising results. Nickel and cobalt hexacyanoferrate(Il) compounds are extremely selective for Cs removal, with distribution coefficients in excess of 106 and remarkable insensitivity to competition from Na and K. They tend to lose effectiveness at pH > - 11, but some formulations are useful for limited periods of time up to pH - 13. Sodium titanate is selective for Sr removal at high pH. The separations are so efficient that simple, batch processes can yield large DFs while generating small volumes of solid waste. A resorcinol-based resin developed at the Savannah River Site gave superior Cs removal compared with other organic ion exchangers; the distribution coefficient was limited primarily by competition from K and nearly independent of Na. The optimum pH was - 12.5. It was much less effective for Sr removal, which was limited by competition from Na. 8 refs., 4 figs., 9 tabs