Nadir toprak elementlerinin solvent ekstraksiyon yöntemi ile değerlendirilme kinetiğinin incelenmesi

In this study, the equilibrium conditions and kinetic studies of solvent extraction processes were investigated for lanthanum, cerium, praseodymium, and neodymium. In the equilibrium studies, effects of extractant, acid and metal concentrations on the solvent extraction of light rare earth elements were examined. Then a single drop apparatus was used for the determination of the reaction kinetics of the solvent extraction process. Column height, extractant concentration, acid concentration, metal concentration, and temperature were the main parameters effecting the reaction kinetics of SX and they were investigated. In conclusion, the rate formulas of the SX reactions were obtained by flux calculations. In addition, thermodynamic properties were determined by using the Arrhenius Equation and Activated Complex Theory. According to thermodynamic properties, the diffusion of the metal-ligand complex into the organic phase was the rate-determining step for the lanthanum and cerium. Besides, both diffusion and chemical reactions were determined as rate-determining steps for praseodymium and neodymium. Reactions at the interface were realized with nucleophilic bimolecular substitution.