Abstract
The simple Langmuir isotherm model is often used to describe the equilibrium behavior of protein adsorption to a wide variety of adsorbents. Estimates of the two adjustable parameters of the Langmuir model, qm and Kd, are usually made by fitting the model equation to equilibrium data obtained from batch equilibration methods. In this work, the possibility of estimating qm and Kd for the adsorption of bovine serum albumin to a cation-exchanger from batch kinetic data was investigated. A rate model based on the kinetic form of the Langmuir isotherm with three adjustable parameters (qm, Kd, and a rate constant) was fitted to a single kinetic profile. The value of the saturation capacity qm identified by this approach was in very close agreement with the qm value determined from equilibrium data. However, the value of the dissociation constant Kd could not be retrieved from the kinetic profile as the model fit was insensitive to this parameter. Sensitivity analysis provided valuable insights into the identifiability of the three model parameters.
