【作者】 孙明；

【导师】 谭欣；

【作者基本信息】 天津大学 ， 环境科学， 2007， 硕士

【摘要】 光催化技术在处理废水中重金属离子方面有独特的优势,特别适用于组成复杂和低浓度废水的处理,该技术有广泛的应用前景。目前对TiO₂光催化剂的研究趋向两种形态,颗粒和固定在载体上的光催化膜。固定化光催化膜材料的比表面积有限,没有颗粒光催化材料的比表面积大,所以光催化膜的光催化效率没有颗粒光催化剂的效率高。但是颗粒光催化剂由于粒径太小,难于从反应混合物中分离回收出来,特别是在工业废水光催化处理过程中,由于分离困难造成颗粒光催化剂的流失率大。为了解决颗粒光催化剂的分离回收这一关键问题,我们制备了磁载光催化剂。我们的方法是以微米级Fe₃O₄作为载体,用溶胶-凝胶方法在Fe₃O₄表面进行SiO₂和TiO₂的包覆,制得磁载光催化剂TiO₂/Fe₃O₄和TiO₂/SiO₂/Fe₃O₄,研究表明:以甲酸为催化剂经溶胶-凝胶过程在磁核Fe₃O₄表面包覆SiO₂后效果较好;TiO₂/SiO₂/Fe₃O₄的磁性能和光催化活性比TiO₂/Fe₃O₄的磁性能和光催化活性有显著的提高。用光化学还原法在TiO₂/SiO₂/Fe₃O₄表面沉积贵金属Ag和Pt,以提高其光催化活性。研究表明:贵金属的沉积对TiO₂/SiO₂/Fe₃O₄的磁性能有影响;与TiO₂/SiO₂/Fe₃O₄相比,适当掺杂量的Ag/TiO₂/SiO₂/Fe₃O₄的光催化活性有所上升,Pt/TiO₂/SiO₂/Fe₃O₄的光催化活性都有所下降。以Cr（Ⅵ）水溶液为目标物对各样品的光催化活性进行了评价,并对影响光催化效率的因素,如Cr（Ⅵ）溶液初始浓度,光催化剂的加入量,溶液的pH值,重复使用次数,进行了考察。更多还原

【Abstract】 Photocatalytic technology has special advantages in the treatment of wastewater with heavy metal ions, especially, the treatment of wastewater which has complicated compositions and low concentration, so this technology has a promising prospect.At present, the research about TiO₂ form has two tendencies: one is TiO₂ powder, another is TiO₂ membrane. Compared with TiO₂ membrane, TiO₂ powder has the larger surface; therefore, its photocatalytic activity is higher. But TiO₂ powder is difficult to be separated from reactants for its small particle diameter. Especially in the system of industrial wastewater, TiO₂ powder has big lost rate when to be separated. In order to solve the problem of TiO₂ powder’s separation and reuse, we prepared magnetic photocatalyst.Our methods are as follows: by using micron-sized Fe₃O₄ as support, prepare TiO₂ and SiO₂ coatings on the surface of Fe₃O₄ to get TiO₂/Fe₃O₄ and TiO₂/SiO₂/Fe₃O₄ by sol-gel method. The results indicated that using HCOOH as catalyst to prepare SiO₂ coating had a better effect by sol-gel process; TiO₂/SiO₂/Fe₃O₄ has better magnetic performances and photocatalytic activity than that of TiO₂/Fe₃O₄. Then we deposited noble-metal Ag and Pt on the surface of TiO₂/SiO₂/Fe₃O₄ by the photodeposition method. The results indicated that the deposition of noble metal had effects to the magnetic performances of photocatalyst TiO₂/SiO₂/Fe₃O₄; compared with TiO₂/SiO₂/Fe₃O₄, the photocataltic activity of Ag/TiO₂/SiO₂/Fe₃O₄ could increase with a suitable Ag loading, but the photocataltic activity of Pt/TiO₂/SiO₂/Fe₃O₄ was all reduced with varying Pt loadings.Finally, using Cr（Ⅵ） aqueous solution as object to evaluate the photocatalytic activity of samples, and we also investigated the effect of the concentration of Cr（Ⅵ） aqueous solution, the amount of catalyst, pH values and reuse times on the photocatalytic efficiency.更多还原