Synergistic Solvent Extraction of Neodymium(III) from Chloride Solutions using a Mixture of Triisooctylamine and bis(2,4,4-Trimethylpentyl) Monothiophosphinic Acid

The synergistic solvent extraction of Neodymium(III) with mixture of triisooctylamine (Alamine 308, R3N) and bis(2,4,4-trimethylpentyl) monothiophosphinic acid (Cyanex 302, (HX)(2)) in kerosene from chloride solutions has been investigated. A significant synergistic effect was found by the addition of Cyanex 302 to Alamine 308. The synergistic enhancement coefficient was calculated to be 44.1 for Nd at a mole fraction of 0.2 of Cyanex 302 in the mixture. Results of the effect of equilibrium pH on the distribution ratio of Nd suggested two moles of H+ released in the extraction of Nd with a mixture of extractants. The effect of variation of one extractant at a fixed concentration of the other extractant has been carried out in order to determine the extracted species as NdClX2.2R(3)N. The endothermic nature of extraction with the mixture of extractants was confirmed by the temperature effect and thermodynamic parameters H, G, and S were calculated.