TiO2/膨润土复合光催化材料的常温制备及性能研究

Preparation and Properties of TiO2/ bentonite Composite Photocatalytic Materials at Room Temperature

摘要:

采用改进的溶胶-凝胶法,在以水为主要溶剂的反应体系中,控制钛酸四丁酯充分水解、缓慢聚合,在 常压、低温(70℃)的温和条件下制备出稳定的TiO₂纳米晶溶胶,并利用TiO₂纳米晶溶胶在膨润土表面负载,获得TiO₂/膨润土复合光催化材料。采用 X 射线衍射、扫描电镜、比表面积测定等研究手段对样品的结构形貌进行了表征,并考察了其光催化活性。结果表明：较高的水用量有利于TiO₂晶体形成,当去离子水:钛酸四丁酯摩尔比大于167:1时,在溶胶体系中出现了锐钛矿型TiO₂纳米晶体；TiO₂纳米晶主要负载于膨润土表面,并未嵌入到膨润土层间结构,但相对于单一膨润土,TiO₂负载显著提高了材料比表面积；当去离子水:钛酸四丁酯摩尔比=192:1时,在紫外光照射下,复合光催化材料表现出最高的光催化活性,对亚甲基蓝的降解率达到93.8%。

Abstract:

In a reaction system using water as the main solvent, the stable TiO₂ nanocrystal sol was synthesized under the mild conditions of atmospheric pressure and low temperature (70^_oC) through the improved sol-gel method with controlling tetrabutyl titanate to fully hydrolyze and slowly polymerize. TiO₂/bentonite composite photocatalytic material was further prepared by the loading of TiO₂ nanocrystal sol on the surface of bentonite. XRD,SEM and BET were adopted to analyze the structure and morphology of as-prepared samples, and their photocatalytic activities were also investigated. The results show that the high water addition amount is conducive to the formation of TiO₂ nanocrystals. When the molar ratio of deionized water: etrabutyl titanate is higher than 167:1, the anatase TiO₂ nanocrystals appear in the sol system. TiO₂ nanocrystals are mainly loaded on the surface of bentonite rather than embed into the structure between bentonite layers. However, compared with a pure bentonite, the TiO₂ loading significantly increases the specific surface area of the material. When the molar ratio of deionized water: etrabutyl titanate is 192:1, the composite photocatalytic material shows the highest photocatalytic activity under UV light, and the degradation rate of methylene blue can reach to 93.8%.