| Summary: | 碩士 === 明志科技大學 === 化學工程系生化工程碩士班 === 105 === In this study, polyacrylonitrile nanofiber membrane (PAN) was prepared by electrostatic spinning process, which was subjected to heat and alkali treatments to form weak cation exchange membrane with carboxylic acid group (namely P-COOH). The weak acidic membrane was covalently coupled with aminomethane sulfonic acid (AMS) to obtain strong acidic nanofiber membrane (namely P-AMS). The chemical structure and surface morphology of the strong acidic membrane were characterized by FTIR (Fourier Transform Infrared Spectrometer), SEM (Scanning Electron Microscope), and TGA (Thermogravimetric Analyzer) analysis. In these experiments, the pure lysozyme as a model protein was used to search for the maximum adsorption capacity by the P-AMS membrane. The effects of operating parameters (e.g., alkaline immersion time and temperature, and AMS pH) on the adsorption capacity for lysozyme in the modification stages were investigated. The adsorption of lysozyme from the aqueous solutions by the membrane under various conditions (e.g., adsorption pH, lysozyme concentration, adsorption time, and temperature) was also investigated in batch experiments. Results indicated that lysozyme adsorption could be described by the Langmuir isotherm model, being the monolayer capacity positively affected with an increase in temperature. Moreover, a pseudo-second-order rate model has been employed to describe the kinetic adsorption processes and the rate constants increased with increasing temperature. More experiments were carried out using the experimental design method (i.e., Taguchi method) to find the optimal conditions for AMS modification and to obtain high adsorption for lysozyme. Desorption studies showed that the adsorbed lysozyme was removed from the membrane about 100% by using 0.6 M NaCl. Based on the batch experimental results, to purify the lysozyme from chicken egg white by using the membrane chromatography to find the optimal conditions, including adsorption (e.g., adsorption pH, concentration of CEW, and liquid velocity), wash (e.g., liquid velocity) and elution (e.g., concentration of salt and liquid velocity) stages were investigated. The results show that the lysozyme can be recovered with a high yield of 95.08% and a purification factor of 14.34 in a single step.
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