Extraction kinetics of ytterbium(III) by 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester in the presence of isooctanol using a constant interfacial cell with laminar flow

The ytterbium(III) extraction kinetics by 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (HEHEHP) in the presence of isooctanol have been investigated using constant interfacial cell with laminar flow. The stoichiometry of the complex formation reaction between the ytterbium(III) and HEHEHP in the presence of isooctanol had been evaluated. The extraction kinetics data had been analyzed in terms of pseudo-first order constants. From the temperature dependence of rate measurement, the values of Ea, Delta H and Delta S were calculated and it was found that the extraction process was a diffusion-controlled kinetics process with an interfacial reaction. The rate-determining step was made by predictions derived from interfacial reaction models, and through the approximate solutions of the flux equation, diffusion parameters and thickness of the diffusion film have been calculated. (C) 2009 Elsevier B.V. All rights reserved.