Study On The Design And Application Of Nanofiber Based Membrane And Its Module For High Efficient Water Treatment

The increasingly serious water pollution had become a main factor that restricting the development of social economy, and membrane treatment technology was the most effective method of water treatment. However, there were still a series of problems existing now, namely, low filtration flux of membrane and its components, low removal efficiency of contaminants and the membrane surface was easy to be polluted and so on. Therefore, the development of high-performance nanofiber membrane material and the separation technology were of great significance.In this article, melt extrusion phase separation was used to prepare the thermoplastic EVOH nanofiber, with the high pressure jet molding technology EVOH/PET nanofiber composite film was prepared, then taking use of a series of modification and assembly technology the spiral membranes model was obtained. The performance of microscopic morphology, hydrophilicity and filter efficiency of EVOH nanofiber based composite membrane and its components were characterized by SEM, contact angle and the membrane flux test, ect. The influence of physical and chemical structure of nanofiber and its membrane materials on the filtration performance of membrane and its components were researched.The result showed the microscopic pore size of nanofiber composite membrane became smaller, the hydrophilicity and the filtration efficiency improved with the increase in the weight of EVOH nanofiber coating. The contact angle of EVOH/PET nanofiber composite membrane was reduced to 51.6° and the filtration efficiency increased to 99.3% when the coating gram is 8 g/m2. It was difficult to achieve a wide range of application as the interface adhesion between the EVOH nanometer fiber coating and the substrate was too small and the nanofiber composite membrane invalidated when the nanofiber fell off.To solve the above defects, this study used polyester adhesive(PEA) as the adhesive to modify the EVOH/PEA/PET nanofiber composite membrane. And how the filtering quality and peeling strength of the composite membrane were affected by the gram of the nanofiber coating and PEA was also studied. It resulted that after modification by the adhesive, the peeling strength of the nanofiber membrane materials increased obviously, showing an excellent structural stability; and when the EVOH nanofiber coating was 8 g/m2 and the mass ratio between NF and PEA was 1:0.1, the filtration efficiency could reach 99.99%,which is the optimal filtering performance. So an appropriate amount of adhesive could not only improve the structural stability effectively but also could reduce the aperture of the membrane, thus the filtration efficiency of composite membrane enhanced.Assembling a volume type membrane module based on the EVOH/PEA/PET nanofiber composite membrane, and tested its water flux, filtration efficiency and other properties. Results showed the water flux of membrane module kept in 100L/h·m2 for a long time, and its efficiency reached 99.2%. By washing the membrane, the filtration performance of the module could effectively restore, showing that the componentized nanofiber membrane materials had an excellent repeated using performance.To sum up, it could effectively improve the filtering performance of the base materials through the reasonable selection of coating weight of the nanofiber and adhesive, and it provided theoretical and technical guidance for the development of the nanofiber membrane materials and their module of excellent water filtration performance...