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 (PM BP) in liquid paraffin with cersin has been investigated at 343.2 K. U nder some conditions, the synergistic extraction behaviour With PMBP a nd Phen has also been studied. The slope analysis method shows that th e compositions of the extracted species are REA3 and REA3B. pH1/2 valu es were also obtained. Equilibrium extraction constants and thermodyna mic parameters were calculated. The results showed that increasing tem perature is favourable to extraction of heavy rare earth ions with PMB P and more favourable to synergistic extraction with PMBP and Phen. Sy nergistic extraction can be carried out at lower pH.