纳米TiO_2光催化氧化去除水中痕量双氯芬酸的研究

Photocatalytic oxidation of trace diclofenac in water by nanosized TiO_2

以TiCl4为前驱体,采用水解法经不同温度煅烧制备了具有不同理化性能的纳米TiO2光催化剂。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、物理吸附仪、紫外—可见光漫反射吸收光谱(UV-Vis DRS)等手段对纳米TiO2的晶相结构、粒径、孔径分布以及禁带宽度等进行了表征。以蒸馏水配制的双氯芬酸溶液为目标物,进行了纳米TiO2光催化氧化去除双氯芬酸的活性测试,研究了纳米TiO2的理化性能与光催化氧化活性之间的关系。结果表明,经400℃煅烧制得的纳米TiO2样品具有最高的光催化氧化活性,其在紫外光照射60min下对双氯芬酸的去除率为98%左右,比单独紫外光照射高出85百分点。纳米TiO2光催化氧化去除双氯芬酸的反应近似一级反应动力学模型,其中经400℃煅烧制得的纳米TiO2光催化氧化去除双氯芬酸的表观反应速率常数为0.054 54min-1,是普通商用TiO2的2倍左右,与德国Degussa P-25TiO2的光催化氧化活性最相近。

Nanosized TiO2 were prepared by hydropyrolysis process using titanium tetrachloride （TIC14） as the precursor followed by calcinations at different temperatures ranging from 100℃ to 1 000℃, The physicochemical features including crystallite phases, crystallite size, pore size distribution and band-gap of the catalysts were characterized by X-ray diffraction, SEM, TEM, N2 absorption,and UV-Vis DRS adsorption spectrum analysis. The photocatalytic activity of nanosized TiO2 was tested by photocatalytic oxidation of trace diclofenac in water. Moreover,the relationship between the surface structure and the catalytic activity was investigated. Photodegradation results showed that the degradation of diclofenac fit first-order kinetics,nano-sized TiO2 calcined at 400℃ exhibit the highest photocatalytic activity,and the apparent rate constant of diclofenac degradation by nanosized TiO2 （calcined at 400℃ ） was 0. 05454 min-1 ,which was twice of commercial TiOz powder and similar to Degussa P-25 TiO2.