Extraction of Nd(III), Tb(III) and Lu(III) with picrolonic acid in methylisobutylketone

The extraction of Nd(III), Tb(III) and Lu(III) as representatives of lanthanide(III) ions with picrolonic acid (HPA) in methylisobutylketone (MIBK) has been studied from pH 1-2 buffer solutions. The composition of the organic species formed in the organic phase after extraction has been determined by slope analysis to be M(PA)(3) [M = Nd(III), Tb(III) and Lu(III)]. The equilibrium constant values, log k(ex), were deduced to be 2.96+/-0.02, 2.52+/-0.05 and 1.52+/-0.07 for Nd(III), Tb(III) and Lu(III), respectively. The effect of various anions and cations on the extraction of these metal ions has also been studied. Among the masking anions, fluoride, oxalate, citrate and cyanide ions lowered the extraction, whereas presence of Zn(II) Cu(II), Fe(II), Co(II) and Ni(II) has only reduced to 25-87%. The extraction of various other divalent metal ions from pH 2 buffer solution was also studied and high separation factors (10(3)) for the three selected rare earth metal ions were obtained with good selectivity.