Preparation Of Flexible Self-supporting Nanofibers And Their Adsorptionphotocatalytic Performance

With the continuous development of industry,environment pollution is increasingly serious,although in recent years,the country put forward a series of policy to protect the water resources,water pollution control has a positive improvement,but the problem is still severe water pollution,in the face of the current environmental problems,how to develop efficient,clean and no secondary pollution of water treatment technology is the key to solve the problems of current our country water pollution,water pollution treatment technology of traditional contains a physical adsorption and biodegradation technology,but the technology already cannot satisfy the needs of the current.Compared with other water treatment technologies,photocatalytic technology has the advantages of mild conditions and complete degradation of pollutants,so it has a wide application prospect.Common light catalyst for powder material commonly,after reaction in aqueous solution can’t recycle reuse,limits its application in actual water treatment,load by 3d with the photocatalyst material,have higher practical application value,generally can be used in water treatment,the three-dimensional load material mainly composed of silica,glass,polymer and carbon materials.However,the supporting materials for photocatalytic water treatment should have the characteristics of strong light transmission,fiber filamentous or honeycomb shape,softness and solid interface bonding.Common loading methods include in-situ loading,chemical bonding,physical electrostatic adsorption,physical embedding,etc.,but they will face the problems of desorption and low photocatalytic quantum efficiency.This paper focuses on the design and synthesis of flexible self-supporting nanofiber composite photocatalysts and the study of adsorption-photocatalysis.The specific surface energy of photocatalytic nanoparticles was increased by adjusting the size of the nanoparticles,and the nanoparticles were further modified on the flexible fibers to investigate the removal effect of the composites on dyes.At the same time,the porous fibers were prepared by electrospinning,and the adsorption and degradation effects of BPA on the morphology,pore structure and composition of the fibers were investigated.We have mainly carried out the following work:（1）Study on the interface regulation and photocatalytic performance of self-supporting flexible fibers supported by nano-TiO₂The loading modes of nano-TiO₂ on different flexible fibers were compared.The influence of the size of TiO₂ photocatalyst and the material of flexible fibers on the loading effect was investigated.Scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Fourier transform infrared spectroscopy（FT-IR）and other techniques were used to characterize the binding mode of the catalyst and support.The stability and activity of the catalyst and the flexible fiber carrier were tested by Rh B cyclic degradation experiments.It is found that the ultra-small size monodisperse TiO₂nanocrystalline photocatalyst（less than 5 nm）can combine with the flexible support more stably due to its larger surface energy.（2）Preparation of porous fibers by electrospinning technology and non-solvent phase separation principleUltra-small size monodisperse TiO₂ nanocrystals have a good effect on organic dyes,but not on refractory organic pollutants such as phenols.The porous fibers were prepared by electrospinning technique,which simulated the natural fiber cotton and adjusted the hydrophilicity and porosity of the fiber membrane by the principle of non-solvent phase separation.The material has a high adsorption effect on low concentration phenol refractory organic pollutant BPA（3）Preparation of Fe₃O₄/g-C₃N₄/TiO₂ nanofibers by electrospinning for visible light catalytic degradation of BPAOne dimensional composite fibers were prepared by introducing Fe₃O₄/g-C₃N₄/TiO₂ into the original solution of electrospinning polymerization to realize the degradation of BPA.The visible light absorption of the composite fiber was improved by the composite of g-C₃N₄ and TiO₂ semiconductor.Fe₃O₄（Eg=0.1e V）can be combined with g-C₃N₄/TiO₂ to form a ternary heterojunction,which can effectively improve the visible light catalytic performance of the composite fiber.The catalytic degradation of BPA by Fe₃O₄/g-C₃N₄/TiO₂ nanofibers under visible light can reach 90%.It was further proved by XRD and other characterization that TiO₂ in the composite fiber is anatase phase.The morphology of g-C₃N₄ on the surface of TiO₂ composite fiber is nano particles by SEM and TEM.XPS spectrum analysis proves that there exists electron flow between Fe₃O₄/g-C₃N₄/TiO₂ to form heterojunction.