Preparation And Properties Of Nanofiber-based Photocata-Lytic Composite Materials

Due to its complex components,large chroma,difficult to solve,and high toxicity,dyeing wastewater can seriously damage the water environment.At present,the traditional water treatment technologies have limited its widespread application range due to problems such as complicated processes,large equipment footprint,and easy secondary pollution.The photocatalytic oxidation technology,which is based on semiconductor catalyst,has broad application prospects in the field of wastewater treatment due to its advantages of low price,wide range of catalytic substrates,high efficiency and rapidity.However,the photo-catalyst nanoparticles agglomerate easily lead to loss of activity in the actual use,which greatly limits their industrial application prospects.Meanwhile,the catalyst recycling process is complicated.In view of the above-mentioned problems,we intends to use electrospinning technology and biological culture method to prepare a variety of nanofiber materials.Then,we use them as carriers to prepare supported photocatalysts,and study the ability to degrade dyeing solutions of the prepared nanofiber-based photocatalytic composites.mainly include:(1)Polylactic acid/silver-loaded titanium dioxide(PLA/Ag-TiO2)and polyvinyl alcohol/polyamide 6/titanium dioxide(PVA@PA6/TiO2)composite nanofiber films were prepared by electrospinning technology.The morphology and structure of the composite nanofiber films were analyzed.The results show that the TiO2-loaded composite nanofiber films can be successfully prepared by using the electrospinning technology.The nanofibers are relatively unifo-rm in thickness and well-formed.Also,the addition of photocatalyst did not have much effect on the morphology of nanofibers.Before and after loading,the crystal form of titanium dioxide did not change.(2)During the cultivation of Acetobacter xylinum,TiO2-loaded bacterial cellulose composite material(BC/TiO2)was prepared by in-situ growth.Secondly,the BC/TiO2 composite material was treated by plasma,and then nano silver,as a co-catalyst,was deposited on the surface of the composite material through an electroless plating process.Finally,the bacterial cellulose loaded with silver and titanium dioxide was obtained.Observed by scanning electron microscope,TiO2 can naturally embedded into the three dimensional network structure of bacterial cellulose,and electroless plating can deposit nano silver particles uniformly on the surface of bacterial cellulose.(3)TiO2/polypropylene fusion-sprayed nonwoven/bacterial cellulose(TiO2-load PNBC)composite film was prepared by the combination of extraction and leaching method and biological culture method.The morphology of TiO2-load PNBC composite film was analyzed.It revealed that bacterial cellulose was filled on the surface and inside of the polypropylene nonwoven fabric,and the TiO2 particles were firmly coated between the two fibers.(4)Methylene blue and reactive red X-3B were used to simulate dyeing wastewater,and the 300 W mercury lamp was used as an ultraviolet light source.The factors such as the initial concentration of the substrate solution,the pH value of the solution and the number of repeated uses were investigated for the photocatalytic degradation of dyes.By investigating the photocatalytic performance of the nanofiber-based photocatalytic composites,it was confirmed that when the reaction time is constant(2 h),the nanofiber-based photocatalytic composites prepared in this study have good degradation ability for methylene blue and reactive X-3B.The degradation process of the nanofiber-based photocatalytic composites accorded with the quasi-first-order kinetic equation,which was in good agreement with the L-H model.When the initial concentration of the methylene blue solution increases,the ability of the nanofiber-based photocatalytic composites to remove methylene blue decreases.Then,the nanofiber-based photocatalytic composites have a better degradation effect under the alkaline conditions.Finally,through repeated experiments on the nanofiber-based photocata-lytic composites,it was found that they can still maintain good catalytic degradation ability after repeated use.The nanofiber based photocatalytic composite materials not only solve the problem that the nano-catalyst is difficult to recycle,but also have a good photocatalytic degradation effect,which have practical significance for the industrial application of photocatalytic technology.