Kinetic modelling of Fe³⁺ ion uptake by zeolite from water

Abstract

The ability of the natural clinoptilolite (Cp), and its Na–enriched form (Na–Cp) to remove iron ions from acid aqueous solutions has been investigated in the batch system at the initial concentration of 100 mg Fe³⁺/L, <i style="mso-bidi-font-style: normal">p</i>H value of 1.90, and the equilibration time of 30–300 min. In order to establish the Fe³⁺ uptake behaviour, the rate controlling step of the process and to determine the coefficients, the ion exchange kinetics have been investigated and the different models usually applied are used for description of adsorption kinetics. The Fe³⁺ uptake by Cp and Na-Cp is evaluated based on the first–order kinetics, modified Freundlich and Elovich models, parabolic diffusion and heterogeneous diffusion models. Developed models can successfully describe the ion exchange processes between Fe³⁺:Cp and Fe³⁺:Na–Cp. In addition, the results show that the natural Croatian clinoptilolite enables efficient removal of iron from water.