Modified solution of homogeneous surface diffusion model for adsorption

The homogeneous surface diffusion model (HSDM) has been used extensively to model the dynamics of adsorption of organic compounds onto porous media in natural and engineered systems. A modified finite-difference solution to the HSDM is developed in this paper for multicomponent adsorption in fixed beds. The primary difference between the algorithm presented here and that advanced previously is the alternate selection and structuring of the adsorbent particle boundary conditions. The resulting numerical solution addresses the problems of limited stability and computational inefficiency of the original finite-difference scheme as illustrated in one-, two-, and five-component sample simulations. Comparative sensitivity testing with respect to space and time-step sizes also demonstrates a more clearly defined convergence for the modified solution. The computational speed and ease with which the algorithm can be adapted to a personal-computer code also make it an attractive option alongside more sophisticated, though powerful, numerical techniques such as orthogonal collocation.