Synergistic extraction of lanthanum(III) from chloride medium by mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 and triisobutylphosphine sulphide

The synergistic effect of 1-phenyl-3-methyl-4-benzoyl-pyrazalone-5 (HPMBP) and triisobutylphosphine sulphide (TIBPS, B) is investigated in the extraction of lanthanum(III) from chloride solution. Lanthanum(III) is extracted by the mixture as LaCl2.PMBP.B-0.5 instead of La(PMBP)(3).(HPMBP) which is extracted by HPMBP alone. The equilibrium constants and thermodynamic functions such as DeltaG, DeltaH and DeltaS are determined. The extraction of other rare earth ions by mixtures of HPMBP and TIBPS is also studied and the possibility of separating rare earth ions is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.