Simultaneous determination of intraparticle diffusivity and liquid film mass transfer coefficient from a single-component adsorption uptake curve.

In general, the rate of adsorption involves both rates of liquid film mass transfer and intraparticle diffusion. Many researchers tried to minimize the effect of liquid film resistance when determining the effective intraparticle diffusivity. However, in some cases (for example, small adsorbent particle size), the liquid film resistance may not be easily eliminated in a fixed bed process. Therefore, this research proposed using the shallow bed technique to determine both intraparticle diffusivity (D(S)) and liquid film mass transfer coefficient (k(F)) simultaneously from a single-component adsorption uptake curve (AUC). The task was accomplished by the determination of the Biot number (Bi) from experimental adsorption uptake curve (EAUC). The Bi represents the ratio of the rate of transport across the liquid film to the rate of intraparticle mass transfer. The detailed calculation method is addressed in this paper. The method proposed in this research can be applied in the range of Bi between 0.5 and 200 where both liquid film resistance and intraparticle diffusion are significant.