A kinetic study of the removal of Fe(3+), Cu(2+), Mn(2+) and Zn(2+) cations from solution by natural zeolite (clinoptilolite) was performed. The influence of agitation speed (190, 390 and 645 rpm) and particle size (d(p) < 180 mu m, 1-3 mm and 5.6-6.7 mm) on the rate limiting step of the overall process was investigated. The data obtained was fitted to kinetic models with the Nernst Planck model giving the best fit, showing intraparticle diffusion as rate controlling. The effective diffusion coefficient for each cation was calculated. Intraparticle diffusion was shown to be rate controlling. (C) 2011 Elsevier B.V. All rights reserved.