Ion exchange kinetics and column behavior for thymopentin adsorption on NH-1 resin

Ion exchange kinetics and column behavior were investigated for thymopentin (TP5) on a gel-type cation exchange resin (NH-1). Langmuir isotherm model was well fitted to the ion exchange equilibrium between TP5 and NH-1 resin at pH 2.0. The maximum adsorption capacity was 221.07 mg/g wet resin. Intraparticle diffusion was rate controlling for TP5 into NH-1 resin at pH 2.0 and intraparticle diffusivity of TP5 was 4.50 × 10^-9 cm²/s. Comparison between Nernst-Planck kinetic model and Fick kinetic model, Fick's model was suitable to describe the diffusion of TP5 into NH-1 resin and the effective diffusivity was 5.58 × 10^-9 cm²/s. Taking into account intraparticle diffusion, axial dispersion, nonlinear equilibrium and external mass transfer, column behaviors were suitably described by a mathematical model of fixed bed adsorption.