Fabrication Of PVC/PVDF Composite Filter Membrane And Its Application In Wastewater Treatment

With the intensification of environmental pollution and depletion of water resources,more and more voice and requirements about the recycling and advanced treatment of water are put forward.But the traditional water treatment technology has been unable to meet the requirements of modern people for all kinds of wastewater treatment and reuse.Recently,a large number of the applications of membrane separation technology made a great change on the situation.However,the problems including membrane fouling and high membrane cost also seriously hinder their wide application.Herein,this study developed a novel low cost PVC/PVDF composite filter membrane,and realized the mass production in the membrane factory.Moreover also discussed its antifouling performance and application in different engineering field.Under different blending proportion of PVC/PVDF we prepared the membranes with different characteristics.In the casting solution,PVC and PVDF total concentration was16%.When the PVC concentration was 2%-10%,the blending system was part of the compatible system and the composite filter membrane had the characteristics of typical microfiltration membrane?mean pore size is about 0.5?m?.However,when PVC concentration was 0%,12%,14%and 16%,the blending system belonged to compatible system and the finished membranes had the characteristics of typical ultrafiltration membrane?mean pore size is about 50 nm?.The effect of different molecular weights and mass fraction of PEG and nano-SiO₂ on PVC/PVDF composite filter membrane showed that the membranes modified by PEG and nano-SiO₂ could present obvious increase in the mechanical properties,hydrophilicities,antifouing performance.As the PEG molecular was added,PVC/PVDF composite filter membrane increased by 27%in pure water flux.However,after nano-SiO₂was joined in the membrane the pure water flux of the membrane decreased by 36%.Analyzes believed that the nano-SiO₂ with high surface energy made the polymer chains cannot be fully open in the process of phase inversion into membrane,leading to membrane pore diameter reduced from 0.16?m to 0.06?m.The PVC/PVDF fiber reinforced membrane and its module were prepared in the factory.The research of the influence on membranes by tensile machine speed,metering pump speed and wire wheel speed were conducted in membranes produce process,the results showed that the membrane thickness was bigger,the mechanical behavior was better,the pure water flux was lower with the increase of tensile machine and metering pump speed,while the thickness was smaller,the mechanical behavior was worse,the pure water flux was higher with the increase of wire wheel speed.,The best operation parameters of factory production equipment:the tensile machine speed was 43 r/min;the metering pump speed was 19 r/min;the wire wheel speed was 15.5 r/min.On the different wastewater treatment,the composite filter membrane with different aperture showed its unique advantages.When wastewater containing algae treated by PVC/PVDF composite filter membranemean which mean pore size was about 0.2?m,the membrane could separate the algae from the wastewater,the micro algae recovery rate reached 99%,and most of the organic matter in wastewater removal rate kept at 18.3%.When sludge supernatant processed by PVDF filter membrane which mean pore size was about66.38 nm,the PVDF membrane could separate the sludge from the mixture and the membrane flux could reach to 300 L/?m²?h?,and there was no bacteria can be detected in water samples after dealing with the PVDF membrane.PVC filter membrane mean pore size was18.30 nm,so it could be used for treatment of high chroma wastewater,the PVC filter membrane was able to reject the polycyclic aromatic and heterocyclic macromolecular organic matter in waste water,effectively reduce the chromaticity and the removal rate of macromolecular organic compounds was 60%.