Mathematical relationship between surface emission and diffusion coefficients

This paper analyzes the surface emission coefficient corresponding to any diffusion coefficient expressed as an exponential function of the concentration of diffusing substance in capillary porous solids. Theoretical equations for surface emission coefficient for both sorption and desorption are presented. Procedures to derive the diffusion coefficient and to verify the corresponding surface emission coefficient are made using experimental sorption data of aspen (Populus sp.) wood. It is of interest to note that the theoretical models for diffusion and surface emission coefficients can be established and/or evaluated using the same set of experimental data.