Polysulfone Membrane And Its Performance Study

Because of the good permeability, thermal stability, solvent stability and good strength, polysulfone (PSF) membranes have been widely used in many fields, such as ultrafiltration, microfiltration, reverse osmosis, liquid/liquid or liquid/solid separation, gas separation, hemodialysis, and so on.In this thesis sheet and hollow fiber PSF membranes were fabricated. The morphology and performance of the membranes can be controlled. On the basis of analyzing the morphology of the clinical PSF homodialysis membranes, polyvinylpyrrolidone (PVP), water (H2O), poly(ethylene glycol) (PEG) were used as the additives and immerse phase inversion was used as membranes fabrication method. Pure water flux, bovine serum albumin (BSA) rejection, scanning electron microscopy (SEM) and strength of elongate and break were used to characterize the morphology and performance of the membranes. The morphology of the membrane was controlled by changing the concentration of PSF, temperature of casting solution, kinds of additive, concentration of additive, air gap and so on. It was found that the membrane morphologies were changed by additive and air gap obviously. The parameters for membrane fabrication with good performance were summarized.In order to immobilize lipase onto PSF membrane, PSF ultrafine fiber membrane was fabricated to increase the surface of the membrane. Several parameters (Voltage, Flow rate, Distance, Kinds of additives, Concentration of additives, Post treatment) which affect on the morphology of the fibers were investigated. Scanning electron microscopy (SEM) was used to characterize the morphology. It was found that thicker fiber can be fabricated from these ways: quicker flow rate, shorter distance or fewer additives. Lipase was immobilized onto the ultrafine fiber membrane surface by physical adsorption. The effect of temperature and pH value on the activity of the enzyme were investigated. The thermal stability of the immobilized lipase was investigated, too. Some results were meaningful. Compared to the free lipase, the highest activity appeared at lower pH value of the immobilized lipase, the optimum temperature of the immobilized lipase increased about 10 °C and the thermal stability of the immobilized lipase improved effectively.