Preparation And Properties Of High Performance Polysulfone Hollow Fiber Membranes

In the process of preparing the polysulfone hollow fiber membrane by dry-wet spinning,the conditions such as the interaction between polymer,solvent and additive in the casting solution,the temperature of the casting liquid,the composition of the coagulation bath or the core solution,the coagulation bath temperature,the winding speed and so on during the spinning process will lead to the formation of membrane of different types(such as membrane with high water permeability or high rejection).And the influence of various factors on the membrane structure and the membrane performance were different.In addition,the porous structure of polysulfone hollow fiber microfiltration membranes with high water permeability is poor in stability,and the water permeability decreases with the increase of running time and even storage time.How to improve the stability of membrane structure and reduce the attenuation of water permeability during storage or operation by appropriate post-treatment,or through the spinning-drawing-heat one-step preparation of a more stable high-permeability microfiltration membrane,are important research topics in industrial production and application.In this paper,the composition of the casting solution,the hollow fiber membrane spinning process parameters and the prepared polysulfone hollow fiber membrane were used as the research objects.The tester of membrane water permeability and rejection,scanning electron microscope,ultraviolet spectrophotometer and other equipment were used to tested and analyzed the prepared hollow fiber membranes and the samples treated with different tensile-heat setting conditions.The influences of these factors on the structure and performance of the membrane were studied by controlling the coagulation bath temperature,the height of the air bath,the composition of the core liquid,the type and content of the additives,the polymer concentration and so on.High water permeability ultrafiltration membranes and highrejection ultrafiltration membranes were prepared.The results showed that the polysulfone hollow fiber ultrafiltration membrane with the flux of 1000L/(m2·h)and the ovalbumin rejection of 90%could be prepared at the condition of that the temperature of coagulation bath was 70 ℃ and the height of air bath was 190 mm,the DMAc content in the core liquid was 70%.The results showed that when the concentration of polymer was 33%,the coagulation bath temperature was 30 ℃ and the content of additive was 12%,high rejection rate polysulfone hollow fiber ultrafiltration membrane with 99%PEG6000 rejection and 80%PEG4000 rejection was prepared.In the experiment,high water permeability hollow fiber microfiltration membranes were prepared in different proportions and then heat-treated in an electric blast drying oven.The effects of elongation,heat setting temperature and heat setting time on membrane permeability and structure were studied.The results show that different degrees of stretching-heat setting have a significant effect on the water permeability of polysulfone hollow fiber microfiltration membrane.The best treatment condition in this experiment is 10%elongation,heat setting at 60 ℃ for lOmin,the permeability was higher than that of the primary film 22%.Appropriate stretching-heat setting improves the water permeability and the microporous structure stability of microfiltration membranes.