Aplication of diffusional and kinetic models. Modeling the adsorption kinetics of pyridine onto granular activated carbon

In this work, a surface diffusion model (SDM) obtained in a previous work was validated in a wide range of experimental conditions to predict the adsorption kinetics of pyridine on activated carbon. Moreover, the predictions of SDM model were compared with those obtained by using the first and second-order kinetic models. The results showed that the second-order model adjusted satisfactorily the experimental data and fitted the experimental data much better than the first-order kinetic model. The effect of the stirring speed, mass of pyridine adsorbed, (q(e)), and temperature on the rate constant of the second-order model, (k(2)), was analyzed and equations were proposed to correlate k(2) as functions of q(e) and temperature. Nevertheless, the dependence of k(2) regarding the temperature, stirring speed and q(e) cannot be accurately correlated. On the other hand, the SDM model provided a much better prediction than the second order kinetic model. The surface diffusion can be readily estimated from a correlation recommended in this work, whereas the k(2) could not be predicted for some of the experimental conditions studied in this work.