尿素氮源掺杂二氧化钛对染料可见光脱色的研究

Visible-light photocatalytic decolorization of dye using urea doped TiO_2

采用溶胶凝胶法制备不同尿素氮源掺杂量的光催化剂尿素N/TiO2。尿素氮源掺杂后溶胶平均粒径仍在30～50 nm之间,对溶胶粒径影响不大。尿素氮源掺杂可见光区域的吸收强度明显提高,但吸收光波长没有产生明显的红移。红外谱图分析表明,尿素与TiO2形成新的共价键以此参与钛酸四正丁酯的水解过程。0.01%和0.1%尿素掺杂可以提高催化剂可见光活性,继续增加掺杂量活性反而下降。染液初始浓度提高,催化剂脱色率下降。0.01%尿素N/TiO2可见光下脱色4 mg/L亚甲基蓝溶液,脱色率达92.8%。

The photocatalytic N/TiO2 doped with different amount of urea was prepared by sol-gel method. Doped urea has little impact on the sol＇s mean particle size which is about 30 -50 nm. The doping of urea doesn＇t make the absorption threshold wavelength have an obvious red-shift. However, it leads to an increase in optical absorption intensity in the visible-light region. FI-IR spectra indicate that urea involves in the hydrolysis process of tetrabutyl titanate and forms a new covalent bond. TiO2 doped with 0.01% and 0. 1% urea can increase visible-light photoactivity of the catalyst. The activity decreases as the doping amount continues to increase. The high initial concentration of the dye solution results in a decrease in the decolorization ratio. 0.01% N/TiO2 decolors methylene blue solution （4mg/L） under visible light and the color removal of 92. 8% is reached.