Weber and Morris kinetics model has been utilized to understand the mechanism of adsorption process and to determine the rate controlling step which is mainly depends on either surface or pore diffusion. This is a widely used intraparticle diffusion model, Eq. (10), to predict the rate controlling step. The R2 values (Table 3) for this model were lower compared to those obtained from pseudo-first order and pseudo-second order models. Also, there is high deviation between the calculate and experimental values Dq (%) (Table 3). In order to say that the intraparticle diffusion is the rate controlling step, the plot of qt versus t1/2 (Fig. 5b) should be linear and pass through the origin. As can be noticed from this figure, the plot did not pass through the origin and this deviation from the origin or near saturation might be due to the difference in mass transfer rate in the initial and final stages of adsorption. From these results, it can be concluded that intraparticle diffusion is not the dominating mechanism for the adsorption of both CIP and NOR on prepared carbon.