Gd/N共掺杂纳米TiO_2的制备及对腐殖酸的降解

Preparation of Gd/N-codoped nano-TiO_2 and degradation of humic acid

研究一种利用太阳光进行光催化氧化降解腐殖酸的方法。采用溶胶-凝胶法制备Gd/N双元素共掺杂的纳米TiO2复合光催化材料,用X射线衍射仪(XRD)、透射电镜(TEM)和紫外可见漫反射光谱(Uv-VisDRS)对光催化材料进行表征。以腐殖酸溶液为目标降解物,太阳光为光源,通过对腐殖酸的降解研究Gd/N双元素共掺杂纳米二氧化钛的光催化活性。研究结果表明:Gd/N双元素掺杂样品为锐钛型结构,颗粒平均粒径为17nm,有红移现象出现,可见光范围内光响应增强;它对腐殖酸的降解率随光强的增大而升高,随溶液pH值降低而增大;同时,钆氮共掺杂具有协同效应,当体系pH值为3.0时,适当配比的Gd/N共掺杂光催化剂样品在太阳光下对腐殖酸催化反应5h后,降解率可达85.4%。

A novel method in which the photocatalysis is used to degrade HA in the sunlight was investigated. The Gd/N-codoped nano-TiO2 composites were prepared by sol-gel method. The as-produced samples were characterized by X-ray diffi＇action （XRD）, transmission electron microscopy （TEM） and ultraviolet-visible diffuse reflection spectroscopy （Uv-Vis-DRS）. The photoactivity was evaluated by the photodegradation of HA in an aqueous solution in the sunlight. The results show that Gd/N-codoped nano-TiO2 composite is a type of anatase structure, its average diameter is 17 nm, and the red shift appears in DRS patterns. The HA photodegradation rate increases with the increase of light intensity, and decreases with the increase of solution pH value. Gd and N have synergetic effect on codoped nano-TiO2 composite, with proper ratio of Gd/N, the HA photodegradation rate can reach 85.4% in the sunlight for 5 h and at pH value 3.0.