Kinetic studies of the solvent extraction of UO2(II) and Hg(II) with 4-sebacoylbis(1-phenyl-3-methylpyrazolone-5) in chloroform

The rate of solvent extraction of UO2(II) and Hg(II) in acid solutions and 0.1 M ionic media with 4-sebacoylbis(1-phenyl-3-methylpyrazolone-5) (H2SP) in chloroform has been investigated. The rate of solvent extraction can be represented by, -d (UO22+]/dt = k(f)[UO22+][H2SP]((o))[H+](-1), and, -d[Hg2+]/dt = k(f) [Hg2+][H2SP]((o))[H+](-2), for solvent extraction of UO2(II) and Hg(II) respectively. From the extract ion data the rate constants for the rate determining reactions were calcula ted to be k(f) = 10(-1.98)(UO2(II)) and 10(-4.65) min(-1) (Hg(II)). Formati on of the first mono-protonated uranyl-sebacoylbis(pyrazolonate) chelate ri ng and the process of displacing the dichloro group of the Hg-chelate withi n the complex during extraction of Hg(II) were identified as the rate deter mining steps during the extraction of UO2(II) and Hg(II) by 4-sebacoylbis(1 -phenyl-3-methyl-pyrazolone respectively. The mechanism of the extraction p rocesses based on equilibration and kinetic data were presented and discuss ed.