【作者】 刘子全；

【导师】 朱波；

【作者基本信息】 山东大学 ， 材料学， 2007， 硕士

【摘要】 较之于固定化TiO₂,纳米TiO₂悬浮体系在光催化降解有机污染物时,具有催化剂有效比表面积大,催化活性高的特点。然而,对于纳米TiO₂颗粒目前还缺乏有效的分离手段。以磁性纳米材料为核,制备出的核壳型TiO₂光催化剂,保留了纳米TiO₂粒子的高催化活性,在反应完成后施加一个合适的外加磁场即可快速有效地分离。用TiO₂光催化材料降解工业废水具有廉价、高效、无二次污染等优点。目前对TiO₂光催化材料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。为了保证较高的光催化效率的前提下解决颗粒光催化剂的分离回收这一关键问题,我们制备了纳米磁性复合体光催化材料。磁载光催化剂是通过在磁性核上包覆具有光催化活性的二氧化钛层制备合成的。这种光催化剂是用于悬浆型反应器的,它在外加磁场的作用下很容易从浆体中分离回收。本文概述了TiO₂光催化剂的光催化原理和负载型TiO₂光催化剂制备的研究进展状况,重点介绍了可磁分离光催化剂的磁载材料的研究进展状况。在大量文献调研的基础上,提出以磁载光催化剂（TiO₂/SiO-2/Fe₃O₄）的制备及其光催化性能研究作为本论文的选题和主要研究内容。本文先采用化学共沉淀法,以FeCl₃·6H₂O、FeSO₄·7H₂O和CH₃（CH₂）₁₁SO₃Na为原料制备了超顺磁性、耐腐蚀的磁性Fe₃O₄粉体。以聚乙烯醇为粘合剂和制孔剂,与Fe₃O₄粉体相结合,形成Fe₃O₄复合小球。通过磁铁验证,该Fe₃O₄复合小球具有良好的磁性。以Fe₃O₄多孔球作为载体,再采用Si（OC₂H₅）₄为主要原料,对磁性核芯进行包覆。并通过溶胶-凝胶法,以C₁₆H₃₆O₄Ti为主要原料,在SiO₂/Fe₃O₄表面包覆TiO₂,制备出磁性悬浮负载型的复合光催化剂。用其对罗丹明B溶液的降解效果作为评价TiO₂/SiO₂/γ-Fe₂O₃光催化活性的依据,并对其制备条件进行了优化,得到了光催化效果较好的磁性复合光催化剂。最后用XRD等手段对样品进行了表征。结果表明,TiO₂/SiO₂/γ-Fe₂O₃的光催化活性优于TiO₂和TiO₂/Fe₃O₄,仅略低于TiO₂/SiO₂。TiO₂/SiO₂/γ-Fe₂O₃具有良好的磁性,方便回收。更多还原

【Abstract】 In the degradation of organic pollutants,Nano-TiO₂ slurries are generally considered as more efficient than immobilized TiO₂ since slurry TiO₂ offers higher specific surface area.However,the TiO₂ nanoparticles are hard to be recovered from slurries after treatment.Magnetic core-shell TiO₂ photocatalyst,which is obtained by depositing a TiO₂ layer onto magnetic materials,keep the high photocatalytic activity of TiO₂ nanoparticls and is easy to be separated under an applied external magnetic field.Industrial wastewater is difficult to be degraded.Photocatalysis by TiO₂ are very promising methods to degrade dye wastewater for cheaper,highactivity,no secondary pollution.At present,the research about TiO₂ form has two tendency;one is TiO₂ powder,another is TiO₂ membrane.Compare with TiO₂ membrane,TiO₂ powder has the larger surface.Therefore,its photocatalytic activity is higher.But TiO₂ powder is not perfect for recovering from treated water system.Magnetic photocatalysts were synthesized by coating a magnetic core with a layer of photoactive titanium dioxide.This magnetic photocatalyst is for use in slurry-type reactors in which the catalyst can be easily recovered by the application of an external magnetic field.The study background and application perspectives of supported photocatalysts and magnetic photocatalysts are introduced.Photocatalytic principle of Nano-TiO₂ is also reviewed.Based on adequate study of background knowledge,we choose the preparation and magnetism as well as photocatalytic properties ptudy of pagnetism TiO₂/SiO₂/γ-Fe₃O₄ to research.In this paper,the magnetic cores Fe₃O₄ have been prepared with FeC1₃·6H₂O and FeSO₄·7H₂O.Then SiO₂/Fe₃O₄ particles have been prepared through precipitation method,and in this reaction the Si（OC₂H₅）₄ is the main material,the Fe₃O₄ is the magnetic core.At lastγ-Fe₂O₃/SiO₂/TiO₂ coated particles have been prepared with C₁₆H₃₆O₄Ti and SiO₂/Fe₃O₄ as precursors by Sol-Gel method.In order to improve the photocatalytic degradation activity ofγ-Fe₂O₃/SiO₂/TiO₂ for rhodamine B,the conditions of preparing were selected and the better photocatalytic activities were received.Its morphology and structure were characterized by XRD and other equipments.The result indicated;the photocatalytic activity ofγ-Fe₂O₃/SiO₂/TiO₂ is better than those TiO₂ and Fe₃O₄/TiO₂,Its photocatalytic activity just a little worse than/SiO₂/TiO₂.The samples ofγ-Fe₂O₃/SiO₂/TiO₂ have good magnetism and it is easy to reclaim.更多还原