TiO_(2)纳米纤维的制备及其光催化降解染料性能

Research on the preparation and the photocatalytic dye degradation performance of TiO_(2) nanofibers

为了提高TiO_(2)光催化性能,采用电纺丝技术和煅烧工艺,以钛酸四丁酯(TBT)为钛源、聚乙烯吡咯烷酮(PVP)为高聚物模板,制备PVP/TBT复合纳米纤维膜,再经煅烧得到连续TiO_(2)纳米纤维。通过SEM、XRD、TG测试对材料的形貌、结构进行表征,并在紫外光的照射下,以亚甲基蓝为目标降解物,使用TiO_(2)纳米纤维为光催化剂进行降解实验。结果表明:在450℃下煅烧得到的TiO_(2)纳米纤维具有良好的光催化活性。在染料质量浓度为20 mg/L,染料与TiO_(2)纳米纤维质量比为1∶75的条件下,20 min时的降解率为93.31%,80 min的降解率为99.83%,效果显著。

The acceleration of industrialization brings with environmental pollution and resource consumption, which has a great impact on sustainable development and people’s life. TiO_(2)has advantages of stable properties, ease to prepare, reusability, low cost and non-toxicity. Because of its excellent photocatalytic performance, it also has been widely concerned in the treatment of dye wastewater. However, TiO_(2)has some disadvantages, such as low utilization rate of sunlight. Only when the wavelength is less than 387 nm, it can excite valence band electron’s transition to the conduction band. The TiO_(2)photogenerated carrier recombination rate is high. It is difficult to treat industrial wastewater with high concentration and large output. In addition, the powdered TiO_(2)is not easy to recycle, causing secondary pollution. Researchers use metal ion doping, nanostructure design, carbon material combination and other methods to modify TiO_(2), which has great application potential.Herein, composite nanofiber membranes are prepared based on electrospinning technology. Continuous TiO_(2)nanofibers are prepared by calcination at a relatively low temperature of 450 ℃. On the one hand, electrospinning nanofibers have large specific surface area and are not easy to agitate. The contact area with organic matter is large, which can improve the light utilization rate and enhance the photocatalytic activity. On the other hand, as a scaffold, electrospinning nanofibers have the advantages of low weight, high porosity and high permeability, which can improve the degradation ability of dyes. Methylene blue is used as the target degradation agent to study the catalytic degradation performance of TiO_(2)nanofibers. We also study the changes of TiO_(2)nanofibers before and after catalysis and the effects of multiple cycles of reaction. The TiO_(2)nanofiber structure increases the specific surface area of the catalyst and can provide more active sites for light reception and dye adsorption. Moreover, TiO_(2)with one-dimensional network structure is favorable for the direction of photogenerated electrons, thus improving the catalytic degradation efficiency of dyes. It is found that the TiO_(2)nanofibers calcined at 450℃ have good photocatalytic activity. When the dye concentration is 20 mg/L and the dye/TiO_(2)nanofiber mass ratio is 1:75, the degradation rate is 99.83% for 80 min. When the dye concentrations are 10mg/L and 15mg/L, and the dye/TiO_(2) nanofiber mass ratio is 1:25, the maximum catalytic efficiencies are 100% and 99.62% respectively after 60 min. Moreover, the degradation efficiency of the prepared nano TiO_(2)fiber can still reach surpass 95%, when it is catalyzed for 30 min in the third cycle, and the effect is significant.Electrospinning TiO_(2)nanofibers have the advantages of high specific surface area and high catalytic efficiency. On this basis, metal doping and carbon composite modification are carried out to further improve the photocatalytic utilization and photocatalytic activity of TiO_(2), which has practical significance and can provide references in the treatment of dye wastewater.