Preparation Of TiO₂-OMMT/PVDF Mixed Matrix Membranes By Electrospinning And Their Photocatalytic Properties

With the persistent development and consumption of products from food,plastic,leather,printing and dyeing,textile,printing,chemical and pharmaceutical industries,generated pollutants are usually discharged into water bodies in large quantities,causing serious pollution to the water environment.These industrial wastewaters are complex in composition,highly toxic and harmful.They pose a serious threat to the ecological environment and even human health,when they are not handled properly.How to effectively remove pollutants from industrial wastewater remains a challenge.Among the various methods to treat organic pollutants,the photocatalytic membrane is an effective approach as it can degrade dirt molecules and has no secondary pollution,providing a high degradation rate in the treatment of organic wastewater.In this work,nano-titanium dioxide（TiO₂）and organic montmorillonite（O-MMT）-TiO₂composite photocatalysts were loaded into Polyvinylidene fluoride（PVDF）matrix by electrospinning to prepare composite electrospun membrane with excellent photocatalyticalperformance.First,nano-TiO₂ particles with photocatalytic properties were prepared by sol-gel method.The characterization analysis showed that the anatase-phase TiO₂ prepared at 400℃had the best photocatalytic activity.In order to solve the shortcomings of large forbidden bandwidth and low photocatalytic activity of nano-TiO₂.The composite particles containing O-MMT with TiO₂were further prepared by sol-gel method.The characterization analysis proved that nano-TiO₂loaded in O-MMT had a large photocatalytic specific surface area.Subsequently,a new type of thermally stable composite photocatalyst O-MMT-TiO₂ was prepared by the transformation of anatase TiO₂ to the rutile TiO₂ phase.The exploration process of synthesized TiO₂/PVDF electrospun membrane shows that when the content of nano-TiO₂ was 0.6wt.%-0.75wt.%,the nanofiber surface of the electrospun membrane became smooth withuniform diameter and relatively dense surface.Furthermore,the electrospun membrane prepared when TiO₂ content was 0.6wt.%and 0.75wt.%had the best photocatalytic degradation performance for the dye solutions.Electrospun membrane with 0.6wt.%of TiO₂ particle shows degradation efficiency of 66.83%and 62.74%for Rhodamine B（Rh B）and Methylene blue（MB）dye,respectively.Whereas,the electrospun membrane with0.75 wt.%of TiO₂ particle shows degradation efficiency of 58.71 and 64.31%for Rh B and MB dye,respectively.The exploration process of O-MMT-TiO₂/PVDF electrospun membrane shows that the 0.45wt.%-O-MMT-TiO₂/PVDF nanofiber show good mechanical properties and photocatalytic properties for Rh B and MB dyes.The degradation efficiency of the dye solutions reached 93.06%and 87.06%for Rh B and MB,respectively.Furthermore,the nanofiber present good reusability during three consecutive cycles.