Uptake properties of radioactive nuclides on microcapsules encapsulating DEHPA extractant

The uptake properties of radioactive nuclides on microcapsules (MCs) encapsulating DEHPA (di-(2-ethylhexyl) phosphoric acid) extractant have been studied by batch methods. The oil drops of DEHPA were uniformly encapsulated in the matrices of calcium alginate (CaALG) gel polymer. The MCs exhibited relatively large distribution coefficients (Kd) above 103 cm3/g for trivalent metal ions (Y3+, Eu3+, Am3+ and Fe3+). The uptake of Eu3+ and Am3+ on MCs attained equilibrium within 1 d, and high uptake percentage above 99% was obtained. The uptake of Eu3+ and Am3+ depended on equilibrium pH, and the Kd values for MCs were larger than those for CaALG in the lower pH region (< pH 2). The MC irradiated at a dose of 188 kGy was still stable without noticeable structural damage yielding normal Kd values over 103 cm3/g for trivalent metal ions. The MCs containing extractants were thus effective for the simultaneous removal of trivalent metal ions from radioactive waste solutions. (author)