Preparation And Photocatalytic Performance Of Titanium-Carbon Nanotube Composites

With the rapid development of textile,food,leather and other industries,although people’s lives have brought great convenience,it has caused a large amount of untreated secondary discharge industrial wastewater,which in turn caused non-point source pollution.The dye industry is a big water consumer,which damages the environment,harms human health,and even causes cancer.Photocatalysis technology is a simple and efficient technology for treating dye wastewater.Titanium dioxide（TiO₂）is widely used in the field of photocatalysis due to its low toxicity and strong oxidizing properties.However,its low photon utilization rate and narrow spectral response range are limited in practical applications.Therefore,the research on suppressing the recombination of TiO₂photogenerated carriers and reducing its band gap has scientific significance and practical application value.Carbon nanotubes（CNT）have a one-dimensional tubular structure with excellent electron transport capabilities,and can form a TiO₂/CNT heterojunction with TiO₂through Ti-O-C covalent bonds.Therefore,in this paper,TiO₂ and CNT are used as the matrix,and the TiO₂/CNT heterojunction composite material is prepared by the sol-reflow method.In order to further inhibit the recombination of photo-generated carriers of TiO₂ and improve the photocatalytic activity,the performance of TiO₂/CNT is improved by doping with rare earths（Ce,La）.The optimized composite photocatalyst and the casting solution are blended to prepare a photocatalytic composite ultrafiltration membrane that is easy to recycle and has a self-cleaning effect.And explore the reaction mechanism of photocatalytic degradation of rhodamine B（Rh-B）.The specific content is as follows:1)The sol-reflow method is used to make TiO₂ grow in situ on the CNT surface through the Ti-O-C bond to form a TiO₂/CNT heterojunction composite material.Photocatalysis experiments show that the excellent electron transport ability of CNT promotes the separation of photogenerated carriers and improves the catalytic activity and thermal stability of TiO₂.And through the capture agent experiment,Mott-Schottky curve to study the photocatalytic degradation mechanism of TiO₂/CNT.2)On the basis of 1),the Ce-TiO₂/CNT and La-TiO₂/CNT composite photocatalyst was prepared by the citric acid complex sol-reflux method.Photocatalytic experiments show that the doping of rare earth Ce and La can cause lattice distortion of TiO₂ to generate oxygen vacancies,and the excited electrons can be transferred to the 4f orbital of Ce,thereby inhibiting photo-generated electron-hole recombination and improving photocatalytic activity and heat stability.The photocatalytic degradation reaction mechanism of Ce-TiO₂/CNT and La-TiO₂/CNT was studied by trapping agent experiment and Mott-Schottky curve.3)On the basis of 2),Ce-TiO₂/CNT and La-TiO₂/CNT photocatalytic composite ultrafiltration membranes were synthesized by non-solvent phase separation method and submerged precipitation phase inversion method.Photocatalysis experiments and ultrafiltration performance experiments show that the combination of ultrafiltration membrane technology and photocatalysis technology can not only solve the problem of difficult recovery of catalyst powder,but also can effectively degrade the adsorbed on the surface of the photocatalytic composite ultrafiltration membrane by blending photocatalysts.Rh-B makes it self-cleaning.