静电纺丝法制备掺硅二氧化钛纤维及其光催化性能表征

发布时间：2018-05-21 07:05

  本文选题：溶胶-凝胶法 + 静电纺丝　； 参考：《华南理工大学》2010年硕士论文

【摘要】： 二氧化钛因其在光照下化学性质稳定,对生物无毒性,无二次污染,且能有效地降解各种有机污染物,已然成为环境污染治理技术的研究热点。常规悬浮相光催化体系存在着分散性差、颗粒易团聚、回收困难等问题,极大地限制了其在废水处理中的实际应用。因此,对二氧化钛光催化剂的负载固定化成为光催化剂今后发展的趋势。本文利用一步溶胶凝胶法结合静电纺丝技术制备出二氧化钛自支撑纤维毡,兼具催化剂活性组分与基体组分双重身份,不仅具有高的光催化活性,还容易回收,具有一定的应用前景。 本论文以钛酸丁酯与乙酸为反应原料,采用一步溶胶-凝胶法,通过原位酯化反应缓慢释放水,实现钛源的均匀水解,生成含钛的线性大分子,获得具有一定可纺性的溶胶体系,通过掺杂不同量的正硅酸乙酯,制备含硅二氧化钛纤维溶胶体系。利用锥板流变仪系统研究溶胶体系的粘度变化,静电纺丝成型设备研究溶胶体系可纺性并制备二氧化钛及其硅掺杂微/纳米纤维毡,并利用扫描电子显微镜研究所得纤维的形貌,结果发现:在钛酸丁酯与乙酸质量之比为1:2.5,反应温度为50℃时,溶剂体系可纺性最佳的反应时间为84h左右。掺杂硅对二氧化钛前驱体纤维直径有细化作用,且掺杂量越大细化作用越明显。固定硅掺杂量为5 mol %,当供液速率从2.33mL/h增大至原来的两倍、四倍甚至八倍时,硅掺杂纤维比未掺杂纤维直径减小3%至30%不等。 探讨了硅掺杂对二氧化钛纤维晶型与晶粒尺寸的影响。由TG-DSC分析可得在掺硅二氧化钛前驱体纤维热处理过程中,前驱体纤维的有机组分的脱除变得缓和,二氧化钛的结晶行为在更高温度下才发生。根据TG-DSC结果在质量与热量变化较快的温度段设置较慢的升温速率,在质量与热量变化不明显的阶段设置较快的升温速率。样品经煅烧后,采用XRD研究不同加热温度、不同掺硅量的二氧化钛的晶型与晶粒尺寸,发现掺杂硅使二氧化钛从锐钛矿到金红石矿的晶型转变温度从800℃提高到900℃,晶粒的生长也受到抑制。用氮气吸附法对掺硅二氧化钛纤维的比表面积与孔结构进行了表征,掺硅量为5%的样品比表面积较大,介孔结构较发达。 以亚甲基蓝为目标降解物,系统研究热处理温度与掺硅量对二氧化钛光催化活性的影响,结果发现,不掺硅的样品在热处理温度为700℃时表现出最高的光催化活性,而掺硅的样品则在600℃活性最高。掺杂硅后二氧化钛样品的光催化活性均得到提高,其中掺硅量为5%时光催化活性最佳,掺硅量进一步增加活性反而降低。
[Abstract]:Because of its stable chemical properties under light, no toxicity to biology, no secondary pollution, and effective degradation of various organic pollutants, titanium dioxide has become a research hotspot in environmental pollution control technology. The conventional suspended phase photocatalytic system has some problems such as poor dispersion, easy agglomeration of particles and difficult recovery, which greatly limits its practical application in wastewater treatment. Therefore, the immobilization of titanium dioxide photocatalyst has become the trend of photocatalyst development in the future. In this paper, TIO _ 2 self-supporting fiber felt was prepared by one-step sol-gel method combined with electrostatic spinning technology. It has the dual identity of active component of catalyst and matrix component, which not only has high photocatalytic activity, but also can be easily recovered. It has a certain application prospect. In this paper, using butyl titanate and acetic acid as raw materials, a one-step sol-gel method was used to slowly release water through in-situ esterification reaction to realize homogeneous hydrolysis of titanium source and to form titanium linear macromolecules. The sol system with certain spinnability was prepared by doping different amounts of ethyl orthosilicate to prepare the silica fiber sol system. The viscosity change of sol system was studied by cone plate rheometer, the spinnability of sol system was studied by electrostatic spinning equipment, and titanium dioxide and silicon doped micro / nano fiber felt were prepared. The morphology of the fibers was studied by scanning electron microscope. The results showed that the optimum reaction time for the spinnability of the solvent system was about 84 h when the mass ratio of butyl titanate to acetic acid was 1: 2.5 and the reaction temperature was 50 鈩，

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