TiO2/SiO2/Fe3O4的光催化性能及动力学

采用溶胶－凝胶法在表面包覆了SiO2的磁基体Fe3O4上负载TiO2,制备了复合光催化剂TiO2/SiO2/Fe3O4。用AFM和XRD等对其进行了表征，并对其光催化降解溴氨酸的pH值、催化剂加入量、初始溶液浓度等条件进行了探讨。结果表明，当pH＝4.0、催化剂用量为2.0 g/L、初始溶液浓度为30 mg/L、光照时间为30 min时，溴氨酸脱色率可达96.2％，COD去除率为85.1％；动力学研究表明：在实验浓度范围内，溴氨酸的光催化降解反应符合一级动力学规律，反应速率常数（k）与初始溶液浓度（c0）的关系为lnk =－0.171lnc0－2.360；经过4次循环使用后，复合光催化剂仍能保持较高的光催化活性和较高的回收率。

Kinetics and photocatalytic activity of TiO2/SiO2/Fe3O4

TiO2/SiO2/Fe3O4 composite photocatalyst was successfully prepared by the sol–gel method with magnetic core SiO2/Fe3O4 as matrix. The samples were characterized with AFM and XRD. The conditions of photocatalytic degradation such as pH，the amounts of photocatalyst, the initial concentration of bromamine acid, etc, were studied in the decolorization of bromamine acid. The results showed that when solution pH was 4.0, the amount of TiO2/SiO2/Fe3O4 was 2.0g/L, the initial concentration of bromamine acid was 30mg/L, illumination time was 30min, the decolorization ratio and the removal rate of COD was 96.2% and 85.1% respectively. Within the range of the initial concentration of bromamine acid, the photochemical decoloration reaction was expressed as first order kinetics, and the effect of initial concentration of bromamine acid on rate constant was: lnk =–0.171 lnc0–2.360. After four times of use, the TiO2/SiO2/Fe3O4 still had good photocatalytic activity and high recovery efficiency.