Preparation And Photocatalytic Activity Of F And Cu Co-doping TiO₂ Hollow Microspheres

Using tetrabutyl orthotitanate as Ti source, hydrofluoric acid as F source, cupric nitrate as Cu source and ethanol as solvent, F doped TiO2 hollow microspheres and F and Cu co-doping TiO2 hollow microspheres have been synthesized via steam heat method. The surface morphology, crystal structure, specific surface area, light absorption property and forms of F and Cu of the two samples were characterized by SEM, XRD, BET, UV-Vis, FTIR. Then, used the two kinds of catalysts degrade the methyl orange and cationic blue solution under visible light respectively and to study their photocatalytic properties. Meanwhile, The F and Cu co-doping TiO2 hollow microspheres under different operational conditions degraded cationic blue were systematically studied. These conditions included catalyst dosage, initial concentration, solution pH and light intensity. Besides, the cyclic utilization properties of the catalyst was also investigated. Finally, the photodegradation mechanism of cationic blue was explored based on the main intermediate products and the characteristics of the reacted catalysts in structure, surface functional groups, and capture of free radicals. The conclusions are as follows:(1) The growth of TiO2 particles can be inhibited by the F doping or F and Cu co-doping, they can make the particle size smaller.The particle size of the sample F-Cu-TiO2 was the smallest, and the distribution was the most uniform.(2) The specific surface area can be increased by the F doping or F and Cu co-doping.But the crystal structure of anatase TiO2 has not changed, and the position of the main infrared absorption characteristic peak of TiO2 also has not changed. However, the crystallinity of TiO2 can be enhanced by doping, and the hydroxyl peak and peak intensity of water can be enhanced.(3) In F and Cu co-doping TiO2, the fluorine atoms were mainly distributed on the surface of TiO2 forme?Ti-F groups,and existed in forms of chemical-adsorption, while the Cu2+ entered into the TiO2 lattice.It leads to the decrease of the band gap and broadens the optical response range of TiO2, which makes the optical absorption edge produced a red shift.(4) The photocatalytic activity of TiO2 can be improved by the F doping or F and Cu co-doping. The sample F/Ti-1 can increase the degradation rate of methyl orange to 98.1%, the removal rate of TOC to 90.29%; and the sample F-Cu-TiO2 can increase the degradation rate of cationic blue to 99.8%, the removal rate of TOC to 92.29%.(5) The optimum reaction conditions for F and Cu co-doping TiO2 hollow microspheres photocatalytic degradation of cationic blue solution were catalyst quantity of 2g/L, initial concentration of 20mg/L, solution pH value of 6,and light intensity of 500w. And the catalyst can be recycled and reused, which has high reuse value.(6) The GC-MS showed that the intermediate products of cationic blue degradation has Hydroxy methyl aniline, p-hydroxyaniline, benzoquinone and oxalate etc. In the end it is oxidized to CO2 and H2O. Superoxide radical plays a leading role in the process of the degradation of cationic blue.