Separation of trivalent actinides and lanthanides from simulated high-level waste using cobalt bis(dicarbollide) ion derivate substituted with diphenyl-N-tert.octyl-carbamoylmethylphosphine oxide

Abstract

Dicarbollide / CMPO / Liquid-liquid extraction / Actinides / Lanthanides / High level liquid wasteSummary. A derivative with cobalt bis(dicarbollide)(1 − ) ion covalently bonded with diphenyl-N-tert.octyl-carbamoylmethylphosphine oxide with a formula [(8-Ph 2 P(O)-CH 2 C(O) Co] − (CMPO-COSAN) has been evaluated for actinides(III)/lanthanides(III) separation from high level liquid waste (HLLW) from PUREX reprocessing. The procedures for HLLW treatment by CMPO-COSAN dissolved in low polar mixture of hexylmethylketone and hydrogenated tetrapropylene (HMK/TPH, 1 : 1) or polar mixture of nitrobenzene/bromoform (NB/BF, 9 : 1) were proposed. The good separation of Am(III)/Ln(III) from bulk of fission products was achieved. The trivalent radionuclides were effectively stripped from the loaded organic phase by using ammonium citrate or mixture of ammonium citrate and ammonium diethylenetriamine pentaacetate (DTPA). The co-extraction of some undesirable elements as Zr, Mo, Pd was suppressed using oxalic acid and HEDTA in extraction and a scrub steps. However, co-extraction of Ag has to be solved, yet.