Kinetics and diffusion processes in colour removal from effluent using wood as an adsorbent

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 X 10^-13 cm²s^-1 to 18 X 110^-13 cm²s^-1 for Astrazone Blue at 18°C and from 3 X 10 ^-1:3 cm²s¹ to 8 X 110^-13 cm²s^-1 for Telon Blue at 18°C. The variation in diffusivities is attributed to boundary layer effects.