| Kinetics and equilibrium of ion-exchange adsorption system is vital in the design and optimization of bioseparation. However, the theory of ion-exchange adsorption chromatography is not complete. The study hereinafter did something about the ion-exchange adsorption theory on peptides.Thymopetin( TP5) is studies as the model peptide and cation ion-exchanger NH1 the adsorbent. Static experiments for sorption behavior of TP5 in different conditions are observed. It indicates that along with the increase of pH, the electrostatic force between TP5 and the cation-exchange adsorbent decreases and the adsorbing capacity is lower. This property should be used for wash down the absorbed peptides.The ion-exchange adsorption kinetics of TP5 to the cation exchanger NH1 were studied in batch stirred cell. Two diffusion models, that is, pore diffusion and parallel diffusion model, were discussed in our paper to analyze the mass transfer of TP5 in the pore of matrix. The diffusion coefficients were determined by fitting uptake curves of TP5 adsorption to NH1 in different conditions (e.g. temperature, pH). The result showed that all of diffusion models could fit uptake curves of TP5 well.When pH increases, the ion interaction between TP5 and the exchanger is weakened, the absorbing capacity and diffusion coefficient decreases. This feature is used for desorption of TP5 from the ion exchanger. At the same time, the studies on dynamic absorption of TP5 onto NH-1 resin verified the theory of static absorption thermodynamics. The absorption releases heat, which is not positive for the processing of absorption.At the same time, the desorption features of TP5 on NH1 resin is studied. The desorbing condition is optimized to 0.05 N of ammonia. The desorption rate is 100% and the purity of TP5 is above95%.Interaction between TP5 and ion exchanger are described in detail. The results reported in the thesis provided an insight into ion-exchange adsorption equilibria and kinetics of peptides.
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