Synergistic extraction study of samarium(III) from chloride medium by mixtures of bis(2,4,4-trimethylpentyl)phosphinic acid and 8-hydroxyquinoline

The extraction behavior of samarium(III) with mixtures of bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex272, H2A2) and 8-hydroxyquinoline (HQ) in heptane has been investigated from chloride medium. The mixtures are proved to have higher selectivity when applied to the extraction of the samarium compared with single extractant, the largest synergistic enhancement factor can be calculated to be 233 at pH 4.0. The results show that Sm3+ is extracted into heptane as Sm(OH)2Q(HA)2(o) or Sm(OH)2Q(HQ)4(HA)2(o) with synergistic mixture. The equilibrium constants have been determined. The result shows that the synergistic extraction system not only shows perfect capacity of synergistic extraction, but also overcomes emulsification of 8-hydroxyquinoline.

► The maximal synergistic enhancement could be obtained at a ratio of Cyanex272 to HQ of 1 to 1.
► The largest synergistic enhancement factor was 233 at pH 4.0.
► The extraction is an exothermic process.