A new methodology for estimation of second order reversible interaction apparent adsorption and desorption rate constants of protein binding kinetics onto resins in packed-bed columns

In this study, a simple and effective technique for characterizing apparent kinetic parameters of protein adsorption in a recycled packed bed column (RPBC) is presented. The apparent kinetic parameters of bovine serum albumin (BSA) onto a weak base ion exchange resin (Duolite A 568) were estimated in a recirculation system. Reservoir BSA concentrations were obtained for different column flow rate, column L/D ratio and initial column feed BSA concentration, and the governing mathematical equations based on kinetic rate constant model were numerically solved employing an implicit finite difference method. The effects of these operational parameters on the adsorption performance were determined only by monitoring reservoir BSA concentration. It was observed that, with increasing flow rate up to an upper limit film resistance decreased and apparent forward adsorption rate k_f, increased, while increasing flow rate any further decreased kf due to insufficient contact time and enforced compressibility. While k_f was significantly enhanced at higher column L/D ratios under fixed operational conditions, increasing feed BSA concentration decreased kf at high volumetric flow rates most likely due to decreased BSA diffusion rate. The presented model is easily applicable to estimate column performance under a wide range of operating conditions and does not require the simultaneous measurement of inlet and outlet protein concentrations of the column.