【作者】 高帅；

【导师】 张秀玲；

【作者基本信息】 大连大学 ， 材料物理与化学， 2010， 硕士

【摘要】 悬浮体系纳米TiO2光催化剂具有比表面积大,催化活性高的特点而成为一种应用广泛的光催化剂,但存在着催化剂与催化体系的分离难题。为此,将TiO2负载在空心玻璃球、沸石、活性炭等载体上制备负载型光催化剂,而由于上述载体较小的比表面积,降低了TiO2的负载量和光催化活性。另一方面,TiO2的太阳光利用效率也限制了其在工业生产中的应用。纳米磁性颗粒因其具有较大的比表面积和良好的分离回收特性,将其作为光催化剂的载体可解决悬浮体系中纳米TiO2颗粒难以分离回收的困扰,较之其他载体,磁载TiO2光催化剂已成为新的研究热点。为了进一步提高TiO2光催化剂的光催化活性,拓宽其光谱响应范围,人们通过各种手段对TiO2光催化剂进行改性处理,取得了较大进展。其中等离子体技术在材料制备和改性中的应用,开辟了等离子体材料工艺的新领域。本文采用化学共沉法制备CoFe2O4磁粒子,用TiCl4水解法制备了CoFe2O4/TiOX复合粒子,在100℃烘干,350℃焙烧2小时,制备了负载牢固的核壳型CoFe2O4/TiO2光催化剂,在紫外光源照射下所制备的CoFe2O4/TiO2光催化剂显示出较高的甲基橙降解能力,利用外加磁场很容易将CoFe2O4/TiO2光催化剂和所处理的污水分离,并可循环使用。在解决了纳米TiO2颗粒分离回收难的问题基础上,为进一步拓宽光催化剂可见光谱响应范围、提高太阳光利用率,引入低温等离子体技术修饰CoFe2O4/TiOX制备了CoFe2O4/TiO2纳米复合光催化剂。运用振动样品磁强计(VSM)技术对样品磁性能进行研究,结果表明:等离子体修饰后的光催化材料仍具有较高的饱和磁化强度,在外加磁场作用下可实现催化剂在水中的分离与回收;并利用X射线衍射仪(XRD)、透射电镜(TEM)、扫描电镜(SEM)、紫外/可见分光光度计(UV-Vis)和傅里叶变换红外光谱仪(FTIR)对所制备样品的物理化学性能进行表征,分析结果表明:等离子体修饰后的复合材料有锐钛矿型TiO2存在;TEM谱图显示磁核CoFe2O4的平均粒径约为20nm,CoFe2O4/TiOX复合粒子的粒径约为30-40nm,TiO2包覆层的厚度为5-10nm。与纯TiO2相比等离子体修饰后CoFe2O4/TiO2样品对光的吸收拓展到整个紫外-可见区,扩大了光谱响应范围;制备出的光催化材料对甲基橙溶液降解的光催化活性评价研究表明:经等离子体修饰后CoFe2O4/TiO2纳米复合光催剂的光催化活性明显提高。更多还原

【Abstract】 In the degradation of organic pollutants, nano TiO2–photocatalyst is a widely used photocatalyst due to its higher specific surface area and high photocatalytic activity. However it is difficult to separate the photocatalyst from treated system. Therefore, TiO2 was be loaded on hollow glass microbeads、zeolite、activated carbon etc, prepared laden photocatalyst, however, the activity of TiO2 photocatalyst was reduced because of the smaller surface area of carrier and the decreases of laden photocatalysts. In addition, the low efficiency of sunlight also greatly limits its practical applications. The nano-magnetic particles were applied to solve the difficulty of photocatalyst separation from the treated water by applying an external magnetic field. Comparing with other carriers, TiO2 magnetic photocalalyst has become a new hotspot. To further enhance photocatalytic activity of the TiO2 photocatalyst, develop the range of spectral, many methods had been used to modify TiO2 photocatalyst, and had made great progress. One of them, plasma technology was applicated in preparation and modification of materials, and opened up the new areas of material technics.In this paper, the core-shell CoFe2O4/ TiO2 magnetic nano-photocatalysts were prepared by hydrolysis of titanium tetrachloride precursor in the presence of the CoFe2O4/TiO2 magnetic photocatalysts. The core-shell structure of the CoFe2O4/TiO2 magnetic photocatalysts were dried at 100℃and calcined at 350℃for 2h. The prepared photocatalysts were easy to be separated from polluted water by using an external magnetic field and showed high catalytic activity for the degradation of methyl orange in water under UV, and could be recycled. In order to broaden spectral response range of visible light about the catalyst’s response and improve the use ratio of sunlight. In this paper, a core-shell CoFe2O4/TiO2 magnetic nano-photocatalyst was prepared by hydrolysis of titanium tetrachloride in the presence of the CoFe2O4 magnetic particles and modified by cold plasma. The magnetic property of the samples was characterized by Vibrating Sample Magnetometer (VSM) analysis. The CoFe2O4/TiO2 magnetic nano-photocatalyst has fairly good magnetic property. The X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scan electron microscopy (SEM), Ultraviolet–visible (UV–Vis) technique and Fourier transform infrared spectrometer (FTIR) were used to analyze the phase structure, size and spectrum response range of the samples. The XRD indicated the anatase TiO2 was formed when CoFe2O4/TiOX modified by plasma. The size of CoFe2O4 particles was about 20 nm. The diameter of CoFe2O4/TiO2 particles is in the range of 30-40 nm. So the shell of TiO2 enwraps closely around the core and the thickness is in the range of 5-10 nm. The UV–Vis spectrum revealed a red shift of the absorption edge to the visible-light region than that of the pure TiO2. Methyl orange was used to investigate the photo-degradation activity of the nano-photocatalysts. The results showed that the photocatalytic activity of CoFe2O4/TiOX modified by plasma is better than that without plasma.更多还原