The measurements of the intrinsic diffusivity in pores and surface diffusivity inside the porous materials in liquid phase

Abstract

In this work, an improved mathematical model was proposed for simulation of the diffusion of dibenzothiophene (DBT) molecules inside the porous materials in liquid phase. The experimental data of the diffusion were obtained in some silica adsorbents with uniform pore structure. The intrinsic pore diffusivity and intrinsic surface diffusivity of molecules were obtained through optimizing the parameters in the mathematical model with the experimental data. The bulk diffusivity of molecules in solution was obtained when the pore size of the silica adsorbents was large enough. The correlation of the intrinsic pore diffusivity with the ratio of diffusion molecular size to pore size of porous materials was established. In addition, the effect of pore size on the ratio of surface mass transfer to total mass transfer was studied and it was found that the smaller the pore size of porous materials, the higher the ratio of surface mass transfer to total mass transfer.