Solvent extraction of thorium,lanthanum and europium ions by bis(2-ethylhexyl)phosphoric acid using 2-nitrobenzo-18-crown-6 as ion size selective masking agent

摘要

The separation of thorium,lanthanum and europium ions has been improved by acidic extractant bis(2-ethylhexyl)phosphoric acid(DEHPA)in cyclohexane using 2-nitrobenzo-18-crown-6(NB18C6)as a selective masking agent.The presence of NB18C6 shifts the extraction curve of lanthanide ions versus pH towards higher pH region.NB18C6 was efficient masking agent towards lanthanide ions and a better separation was obtained as compared to 18C6.The stability constants of the lanthanide-crown ether complexes in aqueous phase and the thermodynamic parameters associated with the extraction process were evaluated.