Kinetics of Zinc Recovery from Spent Pickling Effluents

This work has focused on the study of the kinetics of zinc removal from spent pickling effluents by means of membrane-assisted solvent extraction (NDSX), as the main step in the valorization process of the metal. Tributyl phosphate (TBP) and service water were used as extraction (EX) and back-extraction (BEX) agents, respectively. Working with hollow fiber membrane contactors, kinetic experiments were performed in order to analyze the influence of operation variables on the rate of zinc separation. A mathematical model that considers diffusion through the organic membrane as the main kinetic resistance was developed, and the membrane mass transport coefficient was estimated by means of the parameter estimation tool gEST (from gPROMS) to obtain a value of Km = 3.89 × 10-4 m/h. Simulated results agreed satisfactorily with experimental data, thus confirming the validity of the kinetic model and parameters.