Fe2O3/TiO2负载膨胀珍珠岩光催化降解罗丹明B

为获得高效催化活性的光催化材料，研究不同煅烧氛围对材料在可见光下催化性能的影响，以膨胀珍珠岩（EP）为载体，采用溶胶-凝胶法，在不同煅烧氛围（O₂和/或NH₃）下制备Fe₂O₃/TiO₂负载EP的光催化复合材料〔Fe₂O₃-TEP（O₂）、Fe₂O₃-TEP（NH₃）、Fe₂O₃-TEP（O₂，NH₃）、Fe₂O₃-TEP（NH₃，O₂）〕，采用EDS（X-射线色散能谱）、BET（比表面积及孔径分析）、XRD（X射线衍射）、SEM（扫描电子显微镜）、XPS（X射线光电子能谱）等对复合材料进行表征，并研究了其在可见光下对罗丹明B的光催化降解效果.结果表明:①复合材料成功负载了Ti、Fe元素，负载的TiO₂以锐钛矿型存在，Fe₂O₃的掺杂增强了TiO₂对可见光的响应能力；②不同的煅烧氛围明显影响复合材料的晶粒尺寸、比表面积和光催化性能，其中，Fe₂O₃-TEP（O₂，NH₃）的光催化性能最好，4 h后罗丹明B降解率达到87.59%，Fe₂O₃-TEP（NH₃，O₂）、Fe₂O₃-TEP（O₂）和Fe₂O₃-TEP（NH₃）4 h后对罗丹明B的降解率则分别为65.02%、62.48%和47.48%；③在试验条件下，复合材料的光催化反应符合一阶反应动力学方程，Fe₂O₃-TEP（O₂，NH₃）、Fe₂O₃-TEP（NH₃，O₂）、Fe₂O₃-TEP（O₂）和Fe₂O₃-TEP（NH₃）相应的降解速率常数分别为0.008 3、0.004 3、0.004 3和0.002 7 min-1.研究显示，通过溶胶-凝胶法所制备的复合材料（Fe₂O₃-TEP）经煅烧后所得矿相均一；Fe₂O₃掺杂TiO₂可形成Ti—O—Fe键，减小TiO₂固有的禁带宽度；复合材料光催化性能也受到煅烧氛围的影响，先O₂后NH₃煅烧条件下所得材料的光催化性能最佳. 

Photocatalytic Degradation of Rhodamine B by Fe2O3/TiO2 Coated Expanded Perlite

In order to obtain photocatalytic materials with better catalytic activity and study the influence of different calcination atmosphere on photocatalytic properties of materials under visible light, expanded perlite was used to support nano Fe₂O₃/TiO₂ photocatalysts (Fe₂O₃-TEP (O₂), Fe₂O₃-TEP(NH₃), Fe₂O₃-TEP(O₂, NH₃) and Fe₂O₃-TEP(NH₃, O₂)). The nanocomposites were calcinated in oxygen and/or ammonia atmosphere. The as-prepared materials were characterized by X-ray dispersive spectrometer (EDS), specific surface area and pore size analyzer (BET), X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic degradation of Rhodamine B (RhB) was examined with visible light irradiation. The results confirmed that both anatase and Fe oxides were present in the nanocomposites. The batch catalytic experiment revealed that the Fe₂O₃ increased photolytic capacity of TiO₂ under visible light exposure. The calcination conditions greatly affected the crystallite size, specific surface area and the photocatalytic properties of the as-prepared materials. The calcination with oxygen and ammonia yielded the most capable catalyst, with a highest degradation rate of 87.59% after 4 hours. The results of Fe₂O₃-TEP(NH₃, O₂), Fe₂O₃-TEP(O₂) and Fe₂O₃-TEP(NH₃) were 65.02%, 62.48% and 47.48%, respectively. The RhB degradation followed the first order kinetic model under experimental conditions, and the corresponding degradation rate constants of Fe₂O₃-TEP(O₂,NH₃),Fe₂O₃-TEP(NH₃,O₂),Fe₂O₃-TEP(O₂) and Fe₂O₃-TEP(NH₃) were 0.0083, 0.0043, 0.0043 and 0.0027 min^-1, respectively. This study showed that the composites (Fe₂O₃-TEP) prepared by sol-gel method were anatase after calcination. Fe₂O₃ doped TiO₂ formed Ti-O-Fe bond narrowed band gap of TiO₂. The photocatalytic property of composites was also affected by the calcination atmosphere;the optimum condition for calcination was O₂ followed by NH₃.