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采用聚丙烯酰胺凝胶法制备了TiO2纳米颗粒,利用X射线衍射、扫描电子显微镜和紫外-可见光漫反射光谱分别研究了不同煅烧温度对样品晶相、颗粒形貌和带隙的影响.以甲基橙(MO)为目标降解物,在紫外光照射下考察了制得的TiO2样品的光催化性能.研究结果表明,500℃煅烧制备的样品光催化性能最好;随着催化剂用量的增加,MO降解率呈现先增大后减小的趋势,最佳催化剂用量为4.0 g/L;在pH值不太高时(≤7.2),MO降解率随pH值的升高呈下降趋势.以香豆素为探测剂,采用荧光光谱检测催化剂在紫外光照射下产生羟基自由基(.OH)的情况,研究了煅烧温度、催化剂用量和溶液pH值对.OH产率的影响.研究结果还表明,.OH产率与MO降解率的变化规律基本一致,表明.OH可能是TiO2光催化降解有机染料的主要活性物种.
The TiO2 nanoparticles were prepared by polyacrylamide gel method. The effects of calcination temperature on the crystalline phase, particle morphology and band gap of the samples were investigated by X-ray diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy, respectively. The results showed that the photocatalytic activity of the sample prepared at 500 ℃ was the best. With the increase of the amount of catalyst, The degradation rate of MO increased firstly and then decreased with the optimum amount of catalyst being 4.0 g / L. When the pH was not too high (≤7.2), the degradation rate of MO decreased with the increase of pH value The effect of calcination temperature, amount of catalyst and solution pH on the yield of .OH was studied by using fluorescence spectroscopy to detect the hydroxyl radical (.OH) of the catalyst under UV irradiation. The results also show that , .OH yield and MO degradation rate of the change rule is basically the same, indicating that .OH may be TiO2 photocatalytic degradation of the main active species of organic dyes.