硅藻土负载La~(3+)/TiO_2光催化剂的制备及其光催化性能

以钛酸四丁酯为前驱体,硅藻土为载体,采用溶胶-凝胶法制备TiO_2/硅藻土负载型光催化剂。以硝酸镧为镧源,采用等体积浸渍-焙烧法制备La~(3+)/TiO_2硅藻土光催化剂。通过XRD和SEM对制备的催化剂进行表征,以亚甲基蓝溶液模拟有机废水,考察n(Ti)∶n(Si)及La3+掺杂量对催化剂光催化性能的影响,结果表明,硅藻土可提高TiO_2分散性,降低TiO_2晶粒尺寸,并抑制其由锐钛矿相向金红石相的转变。在n(Ti)∶n(Si)=1∶1、焙烧温度550℃和La3+掺杂质量分数1%条件下,La~(3+)/TiO_2硅藻土光催化剂的光催化活性较好,紫外光连续照射180 min,亚甲基蓝降解率可达99.9%。

Preparation of La3+/TiO2 diatomite photocatalysts and their photocatalytic activity

Using tetrabutyl titanate as the precursor and diatomite as the carrier, TiO₂/diatomite photocatalysts were prepared by sol gel method,and then La³⁺/TiO₂ diatomite photocatalysts were synthesized by using lanthanum nitrate as lanthanum source and the impregnation calcination method. The as prepared catalysts were characterized by X ray powder diffraction and scanning electron microscope. Using methylene blue as simulated organic wastewater,the effects of Ti/Si molar ratios and La³⁺ doping amounts on photocatalytic performance of the photocatalysts were studied. The results showed that the diatomite could improve the dispersity of TiO₂ and reduce the crystal size of TiO₂.In addition,the transformation of anatase to rutile phase could be restrained when diatomite was doped into TiO_2. Under the condition of n(Ti)∶n(Si)=1∶1, La³⁺ doping mass fraction 1%, and calcination temperature 550 ℃, La³⁺/TiO₂ diatomite photocatalyst exhibited the best photocatalytic activity. The degradation rate of methylene blue reached 99.9% under the continuous irradiation of UV light for 180 min.