Mass transfer modelling in clay-based material: Estimation of apparent diffusivity of a molecule of interest

This work is devoted to study the controlled release of a molecule of interest in an external medium. The molecule is previously adsorbed in an organic porous material, encapsulated in a thin clay layer. The experimental release kinetics is investigated for the organic material and the clay-based material in two external media: pure water and saline solution. A numerical modelling was developed to understand the different phenomena that act on the molecule transfer. The results show that the hydration of the clay-based material reduces the release kinetics. Moreover, it was observed that the molecules are released faster in pure water than in the saline solution. This phenomenon is explained by the osmotic pressure difference on both sides of the clay layer. (C) 2018 Academie des sciences. Published by Elsevier Masson SAS.