Preparation And Performance Of Powdered Activated Carbon Modified Polyvinylidene Fluoride Ultrafiltration Membrane

Natural organic matter?NOM?has been found to produce disinfection by-products?DBPs?during the process of chlorination,and how to effectively remove NOM in water purification process has become significant.As a new water treatment technology,ultrafiltration?UF?technology can effectively remove toxic organic compounds,viruses,bacteria and particulate matter and so on,so it has a good application prospect.However,during the application of UF membrane,pollutants will accumulate continuously on their surface,resulting in blockage of membrane pores,formation of membrane fouling,reduction of membrane flux and treatment effect,which limits its wider application.Therefore,the improvement of membrane flux and antifouling performance is an urgent problem to be solved in the application of UF membrane.In this study,we use powdered activated carbon?PAC?as the additive to prepare polyvinylidene fluoride?PVDF?based membranes by blending.The filtrating experiments of humic acid?HA?solution and bovine serum protein?BSA?solution are used to characterize the hydrophilicity and fouling performance of the membranes.The differences between the PAC modified membrane and TiO₂ modified membrane in there structures and properties are characterized by scanning electron microscopy?SEM?,water contact angle measurement,and atomic force microscopy?AFM?,Fourier transform infrared spectroscopy with attenuated total reflection?FTIR?and X-ray diffraction?XRD?.The effects of two inorganic nano additives on the antifouling performance of the ultrafiltration membrane were compared by filtering the HA solution,BSA solution and their mixed solution.This study also combined photocatalysis with ultrafiltration to investigate the antifouling performance of PVDF-TiO₂–PAC membrane under visible light irradiation.The results show that the addition of PAC can reduce the contact angle,increase the porosity,improve the pure water flux and filtration stable flux,and enhance the antifouling property of the PVDF ultrafiltration membrane.Both TiO₂ and PAC can improve the hydrophilicity of membrane,but TiO₂ will decrease the pore size of the finger like holes and cavernous holes in the membrane and PAC will increase the finger like holes.Filtration experiments show that the PVDF-PAC membrane had smaller irreversible resistance,and had stronger antifouling performance than TiO₂ hybrid membrane when facing higher pollutant concentration solution.The introduction of visible light can reduce the contact angle,enhance the hydrophilicity,improve the pure water flux and stable filtration flux of ultrafiltration membrane.In the cyclic filtration experiment,the visible light irradiation can delay the filtration flux decline and improve the antifouling performance of the UF membrane.The addition of PAC can further improve the filtration flux of the PVDF-TiO₂ based membrane under visible light irradiation.