Cesium extraction by calix-mono-crown-ethers; Extractant and solvent effects

Simonnet, M.   ; Miyazaki, Yuji; Suzuki, Shinichi; Yaita, Tsuyoshi

Study of cesium separation from acidic and alkaline waste has been conducted since the 90's. Calix[4]-crown-6-ethers can selectively extract cesium with higher distribution ratios than crown-ethers or dicarbollides. Several authors focused on dioctyloxycalix[4]crown-6 (DOC[4]C6), also tested on real waste in dodecane/TBP mixture. 99.9% of cesium was extracted but TBP, mandatory to solvate the calix-crown in dodecane, lowered the selectivity. The distribution ratio DCs remained also rather low. This study focuses on extractant and solvent effects. Because DOC[4]C6 showed good results and is well-documented, extractants were synthesized by modifying its structure: change of the alkoxy chain length led to didodecyloxycalix[4]crown-6 (DDC[4]C6) and diethylhexyloxycalix[4]crown-6 (DEHC[4]C6); change on the crown-ether led to dioctyloxycalix[4]benzo-crown-6 (DOC[4]BC6) and dioctyloxycalix[4]di-benzo-crown-6 (DOC[4]DBC6). Studies on DOC[4]BC6 and DOC[4]DBC6 can be found in literature. Based on literature study, pure solvents: n-octanol (n=1,2,3), methylcyclohexanone (MCHK), 2-nonanone; and mixtures of 1-octanol + 10% modifiers (nitrophenyloctylether (NPOE), TBP) have been tested.