Adsorption kinetics of nitrate ions on ion exchange resin

Abstract

The aim of this study is to compare empirical (pseudo first-order, pseudo second-order, and Elovich models) and theoretical models (second order chemical reaction rate, film diffusion, and particle diffusion models) in the modeling of nitrate uptake by ion exchange resin. The modeling showed that the pseudo first and second order models describe the experimental kinetic data satisfactorily; however, the estimated rate constants varied significantly with the experimental conditions. In comparison with empirical models, theoretical models describe the experimental data with higher precision. In addition, the relative differences between the computed constants of each theoretical model are much less than the estimations of empirical models. The estimated constants of film diffusion model and particle diffusion model for different sets of experimental data were close to the average values, confirming that these models are indeed superior when it comes to the description of the kinetics of nitrate removal. Finally, the performance of ion-exchange column was evaluated using the particle diffusion model in conjunction with mass balance equation in column, with the results of the model predictions being compared to the experimental breakthrough curves. The selected mathematical equations reproduced the experimental breakthrough data very well.