Kinetics of a Fixed Bed System for Solid Diffusion into Spherical Particles

A solution is presented to the general problem of the transient behavior of a linear fixed bed system where the rate of adsorption is determined by the combined effect of a liquid film and solid diffusion into spherical particles. The result obtained is an expression for the effluent following a sudden change in the influent concentration. It is given in two forms: (a) An exact solution to the problem in the form of an infinite integral suitable for numerical integration. (b) An approximation to the exact solution together with an expression for the leading error term in this approximation. The approximate solution and the error term are given as closed trigonometric expressions which can be easily evaluated.