Estudo sobre equações para quantidade adsorvida e concentração na superfície da partícula em adsorção com modelo de difusão

Abstract

The current work provides kinetic analysis and new equations in adsorption equilibrium process of phenanthrene and pyrene with diffusion model in order to solve partial differential equations problem that integrates the phenomenon of external diffusion mass transfer in the intraparticle layer. The methods are based on the form of solutions and appropriate hypotheses to establish as equations of adsorbed quantity and concentration at the surface of the adsorbed particle. Two unknown functions were evaluated, one related to the concentration function in the liquid (CL) and the other S(t)ϕ(t) the amount adsorbed in time. The parameters E1, Ȝ1, E2, Ȝ2, were first determined when two sets of experimental data were applied, in which the subscript index 1 represents the modified zeolite adsorbent and the index 2 represents the sepiolite adsorbent. Next, the proposed equations were evaluated by the statistical indicators, which showed the goodness-of-fit. Especially, zeolite has more suitable indicators value. Based on the evaluated equations, the mass transfer coefficients ke1, De1, ke2, De2 are determined respectively in order to obtain a dimensionless Biot number. As a result, modified Zeolite adsorbent presents the best adsorption quality in comparison with Sepiolita. The limiting step determined by Biot in the end highlights the diffusion in the pores in the case of zeolite and external diffusion in the boundary layer in the sepiolite.