Preparation of thin film composite polyamide ultrafiltration and PVDF hollow fiber membranes for separation of low molecular silk oligopeptides

摘要

For the separation of sericin and oligopeptides which has been discarded after degumming process, a ultrafiltration membrane with a small pore size was synthesized by interfacial polymerization using low concentration of piperazine and trimesoyl chloride. The membrane had a molecular weight cut-off of 3,000Da. Soap could be removed by adding calcium chloride and filtering with a PVDF hollow fiber membrane. Oligopeptides with a molecular weight of 1,500 to 1,900Da were permeated through the membrane. For the hydrolysis of sericin protein in the packed-bed reactor system, trypsin was immobilized on the silica and the chitosan. The trypsin-immobilized silica particles could be prepared by a cationic surfactant and TMOS. The silica particles were embedded on the Chitosan to increase the size of the beads. The amount of trypsin loading was above 50%. The oligopeptides could be concentrated by nanofiltration membrane. Because of its hydrophilicity and negative charge, serious flux decline was not observed. The concentration factor of the oligopeptides solution was above 5.