USE OF THE LAPLACE TRANSFORM TECHNIQUE FOR SIMPLE KINETIC-PARAMETERS EVALUATION - APPLICATION TO THE ADSORPTION OF A PROTEIN ON POROUS BEADS

The kinetics of the adsorption of human serum albumin (HSA) onto spher ical resin beads (Blue Sepharose CL-6B) in a closed stirred tank have been investigated. The differential equation with appropriate boundary conditions at the grain outer surface may be solved numerically or to various degrees of approximation. Using the Laplace transform techniq ue to solve the equation of interest, we are able to obtain the exact solution to the problem, in the Laplace domain. We assume that equilib rium is described by a linear adsorption isotherm and that the adsorpt ion rate is very rapid compared to diffusion in the adsorbent particle s. A functional description of the experimental data in the time domai n allows us to compute the corresponding Laplace transform and fit it to the exact solution, to obtain the film mass transfer coefficient, k (f), and the effective diffusion coefficient, D-e. The main advantage of this Laplace transform technique is that time-consuming numerical a pproaches are not needed, The two parameters are rapidly and easily fo und via two algebraic fits, one in the time domain followed by another in the Laplace domain. Using the parameters thus obtained, a numerica l solution of the problem is in good agreement with the experimental d ata. Copyright (C) 1996 Elsevier Science Ltd