低温合成TiO_2/Fe_3O_4磁载光催化剂的光催化性能研究

Photocatalytic activities of TiO_2/Fe_3O_4 magnetic photocatalysts

采用化学共沉淀法合成的磁性纳米Fe3O4为磁核,以钛酸四丁酯为原料,通过溶胶-凝胶法,在较低温度下合成了TiO2/Fe3O4磁性光催化剂。利用XRD、TEM、SEM-EDX等分析方法对合成催化剂的相组成、形貌、粒度、元素分布等进行了表征;研究了不同焙烧温度及TiO2/Fe3O4比例对降解罗丹明B光催化活性及磁分离回收性能的影响。结果表明,在100、300和450℃焙烧温度下磁性光催化剂的催化活性依次降低,较低温度(100℃)制备的催化剂具备较高的催化活性;当TiO2质量分数处于67.3%～73.0%时,催化剂既具有较高的光催化降解活性也具有较好的磁分离回收性能;光催化剂TiO2/Fe3O4(100℃,TiO2质量分数70%)在循环使用5次后,在降解75 min时仍能达到对罗丹明B 99%的脱色率和90%的回收率。

Nanosized Fe3O4 particles and a TiO2/Fe3O4 magnetic photocatalyst have been prepared by a coprecipitation method and a sol-gel method using tetrabutyltitanate as a precursor at low temperature,respectively.The phase composition,morphology,particle size and element distribution of the TiO2/Fe3O4 photocatalyst were characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM） and scanning electron microscopy with energy dispersive X-ray analysis（SEM-EDX）.The effects of different calcination temperatures and molar ratios of TiO2 to Fe3O4 on the photocatalytic activity of the material in the degradation of rhodamine B were investigated.The photocatalytic activity of the samples was found to decrease in the order TiO2/Fe3O4（100℃） TiO2/Fe3O4（300℃）TiO2/Fe3O4（450℃）.The TiO2/Fe3O4 photocatalyst prepared at the lowest temperature of 100℃ showed the highest photocatalytic activity because the number of centers for recombination of electron-hole pairs was minimized due to the limited diffusion of Fe3＋ and Fe2＋ ions into the TiO2 lattice.The photocatalytic activity and magnetic recyclability of the magnetic photocatalysts with TiO2 contents in the range 67.3%-73.0% were found to be the best.The photocatalyst TiO2/Fe3O4（100℃,w（TiO2）=70%） gave a rhodamine B decolorization ratio of up to 99% and recovery ratio of up to 90% after light irradiation for 75min.