Abstract: This work reports the influence of the temperature on the selective removal of zinc and iron from a chromium(III) passivation bath by emulsion pertraction technology using Cyanex 272 as extractant and hollow fiber membrane contactors. The results indicate that the kinetics of the separation was largely influenced by the temperature in the range 10-40 °C. The viscosity of the organic liquid phase was measured at different temperatures and extractant concentrations, and the results were fitted to the Riedel and Grunberg and Nissan correlations. The improvement observed from 20 to 40 °C was explained by the increase in the diffusion coefficient of the zinc and iron organometallic complexes through the liquid membrane. However, the remarkably slower zinc and iron separation rates observed at 10 °C in comparison with those at 20-40 °C were attributed to a shift in the driving force due to an endothermic change of the interfacial extraction reaction. The equilibrium parameters at 10 and 20-40 °C were estimated by fitting the experimental kinetic results to the proposed mathematical model. Thus, this work addresses the thermal character of equilibrium and its relevant influence on the separation kinetics of reactive membrane systems.

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