Abstract: | The rates of adsorption of a basic dye, Astrazone Blue, and an acidic dye, Telon Blue, on wood have been studied. The rate controlling step is mainly intraparticle diffusion, although a small resistance due to a boundary layer is experienced. The activation energies for the adsorption of Astrazone Blue and Telon Blue on wood are 16.8 kJ mol?1 and 9.6 kJ mol?1, respectively. The diffusion coefficients vary from 6×10?13 cm2 s?1 to 18×10?13 cm2 s?1 for Astrazone Blue at 18°C and from 3 × 10?13 cm2 s?1 to 8 × 10?13 cm2 s?1 for Telon Blue at 18°C. The variation in diffusivities is attributed to boundary layer effects. |