Detailed kinetics of a diffusion driven adsorption process

. The present work completes information reported previously on Chrystal violet adsorption from aqueous solutions onto Salvinia natans powder. It identifies intraparticle diffusion as the rate determining step within the sequence of four individual stages of the adsorption mechanism. It also demonstrates, that even is somewhat faster, the film diffusion at the solid-liquid boundary is also slow enough to contribute to the overall process rate. The novel use of a simple kinetic model, consisting of two parallel and competing first-order steps, as well as of an algorithm familiar to pharmacokinetics (the method of residuals), individual rate coefficients of both the film and the intraparticle diffusion were calculated simultaneously from the same kinetic curves. The dependence of their values with employed operating conditions consolidates previous findings and conclusions.