二氧化硅整体材料的制备及其吸油性能的研究

发布时间：2018-03-12 23:29

  本文选题：氧化硅整体材料　切入点：正硅酸乙酯　出处：《哈尔滨理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：二氧化硅整体材料是一类具有三维网状孔道结构的新颖块状材料，其外观形貌由合成的模具决定。根据制备工艺的不同，其孔道可由大孔、介孔与微孔中的一种或几种组成。在整体材料中各种孔道的存在有利于传质，，减小背压，骨架结构使柱体具有一定的机械强度，孔道内表面的大量硅羟基便于其它各种官能团的修饰与锚定，这使得其在色谱分离中展现出独特的优势。近年来二氧化硅整体材料在催化剂领域得到了一些示范性的应用。然而目前的制备过程复杂，通常使用的硅源为有机硅源，价格较为昂贵，限制了其在工业中的应用。因此，研究使用廉价的硅酸钠代替常用的有机硅源合成二氧化硅整体材料，并探讨一种简捷的干燥方式保持柱体形貌，这些具有一定的现实意义。 本文分别探讨了使用正硅酸乙酯(TEOS)和硅酸钠两种物质为硅源，在醋酸做催化剂，聚乙二醇(PEG)做为相分离引发剂的情况下，采用溶胶凝胶法合成二氧化硅整体材料。同时考察了水浴温度、聚乙二醇含量、pH值、水含量及干燥条件等因素对二氧化硅整体材料孔道结构、外观形貌产生的影响。结果表明，在TEOS-PEG体系内最佳制备条件为按照质量比为TEOS:PEG:H2O:冰醋酸=1:0.09:1.90:0.26的实验配比在40℃水浴条件下反应24h。在硅酸钠-PEG体系，最佳方案为硅酸钠：聚乙二醇：蒸馏水：冰醋酸的质量比为1:0.10:1.67:1.40，在50℃下恒温18h。合成的二氧化硅整体材料经扫描电子显微镜表明均具有连续的孔道结构。XRD衍射结果表明产物中的骨架结构主要由无定型二氧化硅组成。热重分析说明了在不同温度下材料的失重情况，而且在550℃下煅烧材料能有效的除去体系内的PEG。 在应用方面，将二氧化硅整体材料用C18修饰后对其吸油性能进行初步研究，并对比了两种体系合成的材料在吸油性能上的差异。结果表明，形貌完好的二氧化硅整体材料能将染色的油膜吸附干净。在与油滴的接触角测试中，两类体系的产品接触角均为30°，说明二氧化硅整体材料与油是浸润状态，在实验过程中能吸附水面油膜。
[Abstract]:Silica monolithic material is a kind of novel bulk material with three-dimensional reticular pore structure, the appearance of which is determined by the synthetic mould. One or more of the components of mesoporous and micropores. The existence of various channels in the whole material is conducive to mass transfer, reducing back pressure, and the skeleton structure makes the cylinder have a certain mechanical strength. The large amount of silica hydroxyl group on the inner surface of the pore is convenient for the modification and anchoring of other functional groups. In recent years, silica monolithic materials have been used in the field of catalysts. However, the preparation process is complex, and the silicone source is usually used as organic silicon source. Therefore, the use of cheap sodium silicate instead of common organic silicon sources to synthesize silicon dioxide monolithic materials was studied, and a simple drying method to maintain the shape of the cylinder was discussed. These have certain realistic significance. In this paper, the use of tetraethyl orthosilicate (TEOS) and sodium silicate as silicon sources, using acetic acid as catalyst and polyethylene glycol (PEG) as phase separation initiator were studied. Silica monolithic materials were synthesized by sol-gel method. The effects of water bath temperature, polyethylene glycol content, pH value, water content and drying conditions on the pore structure and appearance of silica monolithic materials were investigated. The optimum preparation conditions in TEOS-PEG system were as follows: TEOS: PEG: H2O: 1: 0.09: 1.90: 0.26. Under the water bath condition of 40 鈩

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