In this work, the uptake capacity of Cr(III) ions in NaX zeolite was investigated. The experiments were carried out in continuous and batch systems at 30degreesC. The batch isotherm evidenced an irreversible shape with a maximum chromium uptake of 3.61 meq/g. The column experiments were carried out at pH = 3.5, with a flow rate of 9 ml/min and an average particle size of 0.180 mm. The dynamic system provided a distinct ion-exchange mechanism, which generated a favorable isotherm with a chromium uptake of 3.27 meq/g. A mathematical model was also applied to represent the dynamics of the sorption of the column. The model considered the axial dispersion in the column and the intraparticle diffusion as the rate-controlling step. The dynamic isotherm was successfully modeled by the Freundlich equation and the mathematical model described well the experimental dynamic data for the feed concentrations from 0.3 up to 3.0 meq/g. (C) 2004 Elsevier Ltd. All rights reserved.