Pore-surface diffusion modeling for dyes from effluent on pith

A new pore-surface diffusion model (PSDM) for batch adsorption systems base d on shrinking core theory has been developed. The new PSDM incorporates po re and surface diffusion into a variable effective diffusion coefficient, b ut the contributions from both pore and surface diffusion are evaluated ind ependently. A further advantage of the new model is that it incorporates a time dependent surface diffusivity based on surface adsorbate concentration . The predicted results have been compared using four sets of experimental data for the batch adsorption of dyes on pith.