Mixed ligand complexes of europium,dialkylphosphoric acids and perchlorate anion

The solvent extraction of europium(III) with di-n-butylphosphoric {HDBP} and di-(2-ethylhexyl)phosphoric {HDEHP} acids in 3-methyl-1-butanol from 0.1 and 1.0M perchlorate medium {Na(H)ClO₄} was studied at pH 1–3. It was found that the composition of the species extracted into the organic phase depended on the concentration of perchlorate anion. In 0.1M Na(H)ClO₄ solutions, simple chelates Eu(DBP)₃ or Eu(DEHP)₃ are extracted while mixed ligand complexes Eu(DBP)₂ClO₄ or Eu(DEHP)₂ClO₄ are also extracted from 1.0M Na(H)ClO₄ solutions. Compared to the extractions from perchlorate solutions, no such change in the extraction mechanism has been observed in chloride solutions containing up to 1.0M Cl^–. The extraction of europium(III) with these extractants into toluene from 0.1M perchlorate or chloride media was studied as well. The extraction species found were identical with those reported in the literature, i.e. {Eu[H(DBP)₂]₃, Eu[H(DEHP)₂]₃}. The extraction equilibrium constants were calculated for all complexes.