过硫酸盐对TiO2/硅藻土复合催化剂光催化效能的影响

Effect of Persulfate on the Photocatalytic Performance of TiO2/Diatomite Composite Catalyst

以硅藻土为载体,通过溶胶凝胶法制备TiO2/硅藻土复合催化剂,并利用扫描电镜(SEM),X射线衍射仪(XRD)对光催化剂进行表征,探究了过硫酸盐对TiO2/硅藻土复合催化剂光催化效能的影响.结果表明,所制备的TiO2/硅藻土复合催化剂中TiO2呈锐钛矿型,TiO2较均匀的负载在硅藻土表面.过硫酸盐能大大提高富里酸的去除效果,90min时,UV254和TOC去除率分别达到92.7%和40.9%,相当于未加过硫酸盐180min时UV254和TOC的去除率.加入过硫酸盐后产生了H+,H+对UV254和TOC去除率的贡献仅占38.7%和24%.随着硫酸盐浓度的增加,水中富里酸的去除率先增加后处于平衡状态.本实验条件下,最佳过硫酸盐浓度为75mg/L.在过硫酸盐存在的条件下,pH值在5~7时,光催化反应效果最为明显.

To investigate how persulfate affects the photocatalytic performance of TiO2/diatomite composite catalyst,the photocatalysts were prepared by a sol-gel method,using diatomite as the carrier.The properties of photocatalysts were characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD)as well.Results showed that the prepared TiO2/diatomite composite catalyst was anatase crystal,and the TiO2 covered the top of the diatomite uniformly.The removal efficiency of UV254 and TOC could reach 92.7%and 40.9%at 90 min with 75 mg/L of persulfate,respectively,which was close to the removal efficiency of UV254 and TOC without persulfate after 180 min of reaction.The addition of persulfate produced H+,which contributed only 38.7%and 24%of the UV254 and TOC removal,respectively.By increasing persulfate concentration,the removal efficiency of fulvic acid in water firstly increased and then stayed at an equilibrium state.Under the conditions of this experiment,the most optimal dosage of persulfate was 75 mg/L.Under the existing of persulfate,the photocatalytic efficiency was the highest with pH from 5 to 7.