Thermodynamic investigations of aqueous-molten paraffin wax liquid-liquid extractions and synergistic extractions of some trivalent rare earth elements

In this paper, liquid-liquid extraction behaviour of RE(III) (RE = La, Sm, E, Yb) by the use of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (PMBP) in liquid paraffin with cersin has been investigated at 343.2 K. Under some conditions, the synergistic extraction behaviour with PMBP and Phen has also been studied. The slope analysis method shows that the compositions of the extracted species are REA₃ and REA₃B. pH _{1 2} values were also obtained. Equilibrium extraction constants and thermodynamic parameters were calculated. The results showed that increasing temperature is favourable to extraction of heavy rare earth ions with PMBP and more favourable to synergistic extraction with PMBP and Phen. Synergistic extraction can be carried out at lower pH.