超声微乳法合成TiO2-SiO2催化剂可见光光催化降解亚甲基蓝

采用可见光下亚甲基蓝的光催化降解为模型反应,考察了超声微乳法经钛酸丁酯水解合成的纳米TiO2-SiO2催化剂的性能,并用XRD和BET对催化剂进行了表征。结果表明:硅胶的加入有效地提高了TiO2-SiO2催化剂的热稳定性,抑制了热处理过程中TiO2由锐钛矿相向金红石相的转变和晶粒的长大。随着焙烧温度和TiO2含量的增加,TiO2的晶粒变大,但比表面积减少。TiO2-SiO2的光催化活性明显改善,可见光照射120min,31%TiO2/SiO2催化剂存在下,有84%亚甲基蓝光催化降解。31%TiO2/SiO2催化剂光降解亚甲基蓝的能力大大优于Degussa P-25和纯TiO2,其降解亚甲基蓝的反应速率常数分别为P-25和纯TiO2的8倍和10倍。

Photocatalytic degradation of methylene blue over nanosized TiO2/SiO2 catalyst synthesized by ultrasonic microemulsion method under visible light

In this paper,nanosized TiO2/SiO2 catalysts prepared by hydrolysis of titanium n-butoxide in microemulsion were as photocatalyst in the degradation of methylene blue in water under visible light.These catalysts were characterized by using XRD,BET specific surface area determination.The XRD and BET results show that the addition of silica gel could effectively improve the thermal stability of TiO2/SiO2 catalyst and suppress the formation of rutile phase and the growth of titanium dioxide crystals during the heat treatment.With increasing of the calcination temperature and the TiO2 content,the crystallite size increased,but BET surface area decreased.The nanosized TiO2/SiO2 catalysts show enhanced photocatalytic activity and under 120 min visible light irradiation,84% of methyl blue in an aqueous dispersion was photodegraded in the presence of 31%TiO2/SiO2.The degradation rate of methyl blue using 31%TiO2/SiO2 was much faster than that using P-25 and naked TiO2 as photocatalyst by 8 and 10 times,respectively.