Study On Catalytic Degradation Of Dyes By Centrifugal Spinning Preparation And TiO₂ Nanocomposite Fibers

Nowadays,resources scarcity and environmental damage have been becoming significant problems in global development.Therefore,more and more attention has been paid to the problems of resources and environment in the development of production processes in various countries.In the textile production process,the discharge of printing and dyeing wastewater caused serious damage to the ecological environment and human health.The treatment of printing and dyeing wastewater is imminent.Physical method and biological method are commonly used in industry.Specifically,physical method can’t completely eliminate pollutants and produce secondary pollution while biological method has a single environment and a long period.Compared with the physical method,the photocatalytic technology of titanium dioxide（TiO₂）directly decomposes pollutants into H₂O and CO₂ through redox reaction.However,the photocatalyst of TiO₂ also has some limitations,such as easy reunion,difficult recovery and no reuse.Nanofibers have been widely used because of their large specific surface area and long fiber length.In this paper,the photocatalytic nano-composite fibers of TiO₂ are prepared by centrifugal spinning and applied to the degradation of printing and dyeing wastewater.Firstly,in centrifugal spinning system,the spinning fluid jet per unit time is controlled by controlling spinneret and rotating speed.In the spinning process,the spinning fluid is regulated by changing the concentration of spinning fluid and solvent ratio.The relationship between fiber morphology and spinning parameters was investigated.The influence of the parameters such as the spinning solution concentration,spinning speed,spinneret aperture and solvent ratio on the morphology and structure of fibers are examined by SEM.The result show that the diameter of the fiber increases with the concentration of spinning solution,the pore size of the spinning wire and the content of acetone,and decreases with the increase of the rotating speed.The morphology and structure of the fibers can be easily controlled by changing the spinning parameters.The best spinning process is as follows:Polyvinylidene Fluoride（PVDF）is 10 wt.%,rotational speed is 12000 r/min,spinneret aperture is 0.4 mm,receiving distance is 12 cm.Under this centrifugal spinning condition,the fibers have good in fiberizing properties,and the fibers have excellent properties.The prepared nanofibers have good hydrophobic properties and the water contact angle can reach130°.Secondly,in order to further increase the specific surface area of the fibers,nanocomposite fibers are prepared by changing the properties of the spinning solution and spinning process.The morphology of the fibers is regulated by acid treatment of the prepared composite fibers according to the principle of rotten printing.The effect of spinning parameters on the morphology of composite fibers was investigated.The nanocomposite fibers were characterized by SEM,BET,XRD and FTIR.The experimental results show that when the concentration of spinning solution is 10wt.%（PVDF/CA=7:3）,solvent acetone/Dimethyl sulfoxide（DMSO）is 6:4,rotational speed is 12000 r/min,spinneret pore size is 0.4 mm,receiving distance is 12 cm.After acid treatment,the surface and internal pore structure of PVDF/CA nanocomposite fibers were obvious.Compared with PVDF fibers,the specific surface area of the prepared PVDF/CA nanocomposite fibers was significantly increased.Finally,controlled preparation of centrifugal spinning based on nanocomposite fiber,the photocatalyst of TiO₂ was loaded on the nanocomposite fibers by blending,and the prepared TiO₂ nanocomposite fibers were used in photocatalytic dye degradation experiments.The photocatalytic degradation properties of different dyes were studied and the degradation rate of the dye was calculated.The results show that the crystalline form of TiO₂ does not change during the blending process,and a large amount of TiO₂ was loaded on the fibers.Under the same condition,the degradation rate of dyes by TiO₂/PVDF/CA porous nanocomposite fibers is significantly better than that by TiO₂/PVDF nanofibers.It also shows that the TiO₂/PVDF/CA porous nanocomposite fibers exhibit high degradation rates for dyes of different concentrations and different dyes,and the TiO₂/PVDF/CA porous nanocomposite fibers has good reusability.After five times of reuse,the degradation rate of methylene blue dye solution remains above 90%.