Research Of PVDF Microfiltration Conductive Membrane Based On Conductive Polymer Blending And Surface Modification

The membrane bioreactor(MBR),which integrates activated sludge treatment system and slurry separation system.Because of its high sludge concentration,compact system structure,high degree of automation and excellent quality of effluent water,MBR has attracted more and more attention from the water treatment engineering and the scientific research community.However,the serious membrane fouling in the process of operation is still the bottleneck of its further development and application.The systematic research had been carried out to identify the effect of external minute electric field on membrane fouling mitigation,which based on conducting polymer polypyrrole(PPy)and 3,4-polyethylene two oxygen thiophene(PEDOT)modified organic conductive membrane to construct an Electric Membrane Bioreactor(E-MBR)with external electric field infliction.According to the technology,a series of systematic studies had been carried out:(1)The PVDF microfiltration membrane casting solution was modified by blending modification,at the same time,polypyrrole was doped by anionic surfactants sodium dodecyl benzene sulfonate(SDBS).The modified casting liquid formed the sponge hole with better retention effect after modification.The conductivity and amount of polymerization of pyrrole on the surface of the membrane were enhanced further when the polypyrrole was adopted by SDBS.The conductive membrane could work as membrane and cathode at the same time,which simplified the membranemodule structure.The flux reduction and membrane resistance increase were mitigated in short term filtration tests based on the conductivity of PPy,when 0.1 V/cm electric field was applied.The effluent turbidity of the modified membrane module was lower than that of the control group in the three cycles total of 180 minutes.(2)Through the gas phase polymerization,the PVDF microfiltration membrane was modified with SDBS as the dopant.The gas phase pyrrole was used for membrane modification to enhance the conductivity and hydrophily.The polypyrrole on blank membrane surface from gas phase polymerization was tight and uniform,which improved the membrane properties and increased the utilization efficiency of pyrrole.The oxidant concentration was 20% Fe Cl3·6H2O(w/v).In short term filtration,the flux attenuation rate of the modified film is obviously reduced after applying the electric field of 0.2 V/cm,and the stable flux after three filtration cycles is about 2 times that of the control group.The flux reduction and membrane resistance increase were mitigated in 3 cycles and 45 days of long term filtration tests when 1.0 V/cm electric field was applied.(3)It had also taken the PVDF membrane as the basement membrane material,the blank membrane was modified by gas phase polymerization of PEDOT.The square resistance rate of the PVDF membrane was 14.07 k?/? after modification with PEDOT.The oxidant concentration was 10% Fe Cl3 · 6H2O(w/v).The hydrophilicity and the surface Zeta potential are also enhanced.The modified membrane showed a certain degree of chemical stability in five repeated chemical cleaning.The modified membrane with 1.0V/cm electric field showed a more stable anti fouling performance and less cake formation on the surface than that of control test after 6 cycles and 48 hours of filtration.