Separation Studies of Pd(II) from Acidic Chloride Solutions of Pt(IV), Ni(II) and Rh(III) by Using 4-Aroyl-3-Phenyl-5-Isoxazolones

Abstract

This study examined the effect influence of various factors on the extraction of Pd(II) to develop a new liquid-liquid extraction mechanism for the selective separation of palladium(II) from its acidic chloride solutions using 4-aroyl-3-phenyl-5-isoxazolones (HA), such as 3-phenyl-4-(4-fluorobenzoyl)-5- isoxazolone (HFBPI), 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and 3-phenyl-4- (4-toluoyl)-5-isoxazolone (HTPI). The extraction strength of Pd(II) with HA were in the following order: HFBPI > HPBI > HTPI, which is opposite to that observed with their pK_a values. HPBI was used to separate Pd(II) from Pt(IV), Ni(II) and Rh(III) metal ions and calculated their separation factors (S.F.) were followed in the order: Pd/Ni (40±0.4) > Pd/Pt (25±0.2) > Pd/Rh (15±0.3 > Rh/Ni (2.7±0.3) > Pt/Ni ≈ Rh/Pt (1.7±0.2). The loading and striping of Pd(II) (1.12×10^-4 mol L^-1) were also examined using 1.0×10^-3 mol L^-1 HPBI in CHCl₃ and 1.0 mol L^-1 HCl, respectively. The results demonstrated that the maximum (97.5%) extraction and desorption (89%) of metal required at least 3.0 cycles. The developed method was applied successfully to the separation of palladium from synthetic water samples.