The extraction of strontium and cesium ions from high ionic strength acid, base, and salt solutions into an organic extractant
consisting of alkyl cobalt dicarbollide and polyethylene glycol (PEG) in diethylbenzene was investigated. Adding hexaethylene
glycol or PEG-400 improved the strontium extraction ≥100-fold, while cesium extraction was decreased at high PEG concentrations.
The extractions are rapid and selective, even in the presence of molar concentrations of sodium ion, suggesting that alkyl
cobalt dicarbollide extractants are useful for the treatment of alkaline nuclear wastes. A method for the synthesis of tetra-n-hexyl(cobalt dicarbollide) is described.