Non-linear Diffusion and Adsorption in Heterogeneous Systems by the Orthogonal Collocation Method

Non-linear diffusion and adsorption problems in heterogeneous systems are investigated in this study. Highly non-linear functions are proposed and are found necessary for the adequate representation of concentrationdependent diffusion coefficients in many practical heterogeneous diffusion and adsorption systems. The nonlinear differential equation governing the diffusion and absorption process can be tackled by an orthogonal collocation method which proves to be an efficient and accurate alternative for simulating the transient solute movement in heterogeneous systems under various operating conditions.