Preparation And Photocatalysis Of TiO₂ Nanofibers By Electrosp Inning Poly （Styrene- Butyl Acrylate） Emulsion

As a typical metal oxide semiconductor, TiO2,with high photocatalytic activity to degradate many kinds of organic pollutants, has become the focus of recent study. This paper reported a green and safe novel method to prepare TiO2 nano fibers by emulsion electrospinning.Five different emulsions were prepared based on the previous study. These emulsions include polystyrene (PS) emulsion, random copolymer poly (styrene-butyl acrylate) (PSBA) emulsion (m (PS/PBA)=2/1), random copolymer poly(styrene-butyl acrylate)(PSBA) emulsion (m (PS/PBA)=1/1), poly(styrene-butyl acrylate)(PSBA) core-shell structure copolymer emulsion (PS/PBA)=2/1), poly(styrene-butyl acrylate)(PSBA) core-shell structure copolymer emulsion (PS/PSBA)=1/1). The glass transition temperature(Tg) of emulsions were changed by adjusting the mass ratio of styrene monomer and butyl acrylate monomer. Then, the effects of the mass ratio and copolymer structure on the morphology of electrospinning fibers were investigated.The five emulsions were compounded respectively with tetra-n-butyl titanate that acted as titanium source. In the research of preparing spinning solution, it was founded that electrospinning solution cannot be prepared successfully by adding nonionic surfactant(5wt%) only. Because of tetra-n-butyl titanate easy to hydrolyze, destroyed the stability of the emulsion. Therefore, acetylacetone as the hydrolysis inhibitor of tetra-n-butyl titanate was also added to after exploration. In order to maintain the stability of emulsion during preparing electrospinning solution, sodium dodecyl sulfate, which is emulsifier, was employed simultaneously. At last the formula of electrospinning solution was setted as:4 g emultion with 1 g tetra-n-butyl titanate,and 1 g tetra-n-butyl titanate with 2 g acetylacetone, the addition amount of nonionic surfactant and emulsifier accountting for 5%o f the latex solid content, the addition amount of polyvinyl alcohol according to the different requirements.During the experimentation, a phenomenon was found that electrospinning solution became more unstable as the longer stirring time. Therefore, the morphology of fibers was effected remarkably by the stirring time.The morphology of fibers can be controlled by adjusting the addition amount of polyvinyl alcohol, when immobilized the content of he other ingredients. Horizontal comparison was carried out by changing the content of PVA among the same emulsion. At the same time, vertical comparison was also investigated by adding same amount of PVA to different emulsion.Apart from the content of PVA and the time of stirring electrospinning solution, the morphology of fibers could be also adjusted by controlling the applied voltage. In this report, four voltage in cluding 10kV,20kV,30 kV,40 kV were applied.TiO2 nanofibers were successfully prepared by calcining the composite nanofibers in muffle. During the process of calcining, the heating rate was optimized at 5℃/min, and the temperature was set at 500℃,550℃,600℃, 650℃,700℃, respectively. The TiO2 nanofibers after calcining still maintained the morphology of composite nanofibers.the photocatalytic activity of TiO2 nanofibers was detected by degrading the efficiency of methylene blue solution at the concentration of 15mg/L. The photocatalytic activity of TiO2 nanofibers with different morphology were tested and compared each other.