Photocatalytic Properties Of TiO₂-Molecular Sieve/Ceramic Fiber Composites

With the rapid development of China’s economy and technology,it is urgent to solve the problems of energy and environment.In recent years,photocatalytic technology,as a new way to treat pollutants,attracts a wide attention of researchers due to its green and environment friendly characteristic.As the most widely used semiconductor photocatalyst,TiO2 has the advantages of low cost and high catalytic activity.However,it also has some disadvantages such as small specific surface area,easy-to-compose e-hole and difficult-to-recycle TiO2 powder.The immobilization of nano TiO2 is one of the most promising approaches to overcome those defects.The immobilization is beneficial to increase the specific surface area of the material and make the recycle of the powder much easier.It provides an effective way to solve the problems of energy and environment.In this work,TiO2 is prepared from butyl titanate;ZSM-5 and MCM-41 molecular sieves are used as adsorption materials;ceramic fiber is used as the base material to increase the macroscopic surface area,which is beneficial to the load of molecular sieve and active component.A series of TiO2-nolecular sieve/ceramic fiber photocatalytic materials are prepared through exchange temperature of preparation and contents of molecular sieve and TiO2.In order to improve the photocatalytic efficiency,CdS is introduced into the photocatalytic materials to prepare CdS-TiO2-ZSM-5/ceramic fiber composites.Samples were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscopy(TEM),Uv-vis diffuse reflection(Uv-vis),X-ray photoelectron spectroscopy(XPS).The photocatalytic performances of the composite materials are evaluated by the degradation efficiency of toluene and rhodamine B.The effects of regeneration conditions on the regeneration performance of TiO2-ZSM-5/ceramic fiber composites were investigated.Research shows:The composite materials show a better degradation performance than the single loading TiO2 materials,because composite materials have not only photocatalysis property but absorption property.The nanoparticles disperse well on the surface of molecular sieve.The contact of photoactive material and molecular sieve provides the basis for the combination of adsorption and photocatalysis.In the degradation experiments of toluene,the contents of molecular sieve and TiO2 in TiO2-ZSM-5/ceramic fiber composite are 45.52%and 12.97%,respectively.The calcination temperature of the composite is 550℃.This composite shows an excellent degradation performance,the degradation rate of toluene can reach 39.99%.The CdS/TiO2-molecular sieve/ceramic fiber composite material has the best photocatalytic efficiency when the Cd/Ti ratio is 1,and the degradation rate of rhodaline B is 42.55%.After the introduction of CdS,photocatalytic activity increased.At the same time,the extending of the regeneration time is beneficial to the regeneration of photocatalytic composite materials.After four cycles of recycling,the degradation rate decreases by 6.1%,materials show a good regeneration performance.In the degradation experiments of rhodamine B,the adsorption speed of the ZSM-5 molecular sieve is slower than that of the MCM-41 molecular sieve when they adsorbed rhodamine B.The contents of molecular sieve and TiO2 in TiO2-ZSM-5/ceramic fiber composite are 55.1 8%and 12.97%,respectively.After the introduction of CdS,material has the best photocatalytic efficiency when the Cd/Ti ratio is 1,and the degradation rate of rhodamine B is 97.64%.The TiO2-MCM-41/ceramic fiber composite has the best photocatalytic effect when the calcination temperature is 550℃ and the concentration of butyl titanate is 0.45mol/L.