Kinetics of zirconium ions adsorption on activated charcoal from aqueous solutions

Abstract

The batch kinetics of adsorption of the zirconium ions from aqueous solutions on activated charcoal has been investigated over a wide range of concentration of zirconium ions (1.0–5.0 g/l) and temperatures (10–50°C). The adsorption process of zirconium ions proceeds via two stages; the first stage is rather fast, followed by a much slower one. The Bangham equation was used to study the kinetics of the zirconium ions' adsorption on activated charcoal. It is observed that the diffusion of zirconium ions into the pores of the activated charcoal controls the kinetics of the adsorption process. Moreover, zirconium ion adsorption obeys the Freundlich and Langmuir isotherms in the concentration range studied. The adsorption equilibrium constant ( k c ) values for zirconium ions adsorption on activated charcoal have also been calculated at different temperatures. Various thermodynamic quantities, ΔG, ΔH, and ΔS were computed from k c values. The results showed that the adsorption of zirconium ions on activated charcoal is an endothermic process.