Anionic alkyl diglycoldiamides with covalently bonded cobalt bis(dicarbollide)(1-) ions for lanthanide and actinide extractions

摘要

Ionic diamides composed of a N,N'-dialkyl diglycolyl complexing group and two cobalt bis(dicarbollide)(1-) anions were synthesized with the aim to develop efficient extraction agents for liquid-liquid extraction of polyvalent cations, i.e. lanthanides and actinides from high-level activity nuclear waste. Compounds of general formulation [{(N,N-(8-CH2-CH2O)(2)-1,2-C2B9H10)(1',2'-C2B9H11)-3,3'-Co)(N',N'-R)NCOC H2}(2)O]Na-2, where R = n-C4H9, n-C8H17, n-C12H25 and 1-C6H4-4-CH3 (1-4), were prepared and characterized by combination of B-11 H-1, C-13 NMR spectroscopy, ESI-MS, HPLC and other techniques. Effects of different nitrogen substitution in the structures of 1- 4 on the extraction properties were tested. The study resulted in the observation that the compounds are significantly (2-3 orders in magnitude) more efficient extractants for Eu(III) and Am(III) than synergic mixtures of organic N, N'-tetra n-octyl diglycolic acid diamide (TODGA) and chlorinated cobalt bis(dicarbollide) at the same concentrations of both groups. Low polar mixtures of n-dodecane (D) and hexyl methyl ketone (HMK) can be applied as an auxiliary solvent for extraction, replacing thus the polar and less environmentally friendly nitro-, fluoro- and chloro-solvents used in the current dicarbollide liquid-liquid extraction process.