TiO_2/wAC复合光催化剂的酸催化水解合成及表征

Characterization and Activity of TiO_2/wAC Composite Photocatalyst Prepared by Acid Catalyzed Hydrolysis Method

以TiCl4为钛源,采用酸催化水解法合成了活性炭(AC)复合光催化剂TiO2/wAC(w:AC的质量分数,%).通过对苯酚、甲基橙以及六价铬的光催化降解,考察了AC含量、反应溶液初始pH值、使用次数对TiO2/wAC光催化剂催化活性的影响,并采用重力沉降法测试了催化剂分离性能.采用XRD、DRS、FTIR、SEM、低温液氮吸附等对光催化剂晶相结构、光谱特征、表面结构等进行了表征.结果表明,适宜AC含量的TiO2/wAC(wAC=5%,记为5AC)具有较高的光催化活性.AC掺杂可减小TiO2粒子凝聚,而对TiO2的晶相结构、晶粒大小以及表面性质影响不大,对TiO2能阈结构不产生影响.TiO2与AC结合牢固,接触界面处有Ti—O—C键生成.TiO2/5AC表现出高光催化活性的主要原因是,AC所提供的适宜高浓度环境及对纳米尺寸TiO2团聚的有效抑制.TiO2/5AC的高活性,不易失活,易分离以及活性受pH变化影响较小的特性,使其在实际废水处理方面具有潜在应用价值.

TiO2/ AC （activated carbon） composite photocatalysts were prepared by acid catalyzed hydrolysis method followed by calcinations in N2 atmosphere. Photocatalytic activity of TiO2/wAC （w： the mass fraction of AC, %） was investigated through the photocatalytic degradation of phenol, methyl orange, and Cr^6＋ in the present of TiO2/wAC. The separability of TiO2/AC was determined by gravity-sedimentation. XRD, DRS, FTIR, SEM, and N2 adsorption isotherm were used to characterize the crystal structure, spectra characteristics, and surface properties of the obtained catalysts. The results showed that TiO2/wAC catalysts with optimal AC content 5%（w） exhibited more higher activity than P-25 and TiO2, as well as good decantability, less activity lost after several runs and less sensitive to pH change. Result of DRS revealed no electronic change when AC was added. Better TiO2 distribution and less agglomeration can be achieved when optimal AC content adopted. Result of FTIR suggests that a conjugation effect was presented between the AC bulk and Ti-O bond. Suitable pollutant concentration environment and less agglomeration provided by AC was the main cause for the high activity of TiO2/5AC. The performance of the prepared TiO2/5AC catalyst revealed great practical potential in waste water treatment.