TiO2/PS/Fe3O4 光催化剂的低温制备及其光催化和磁回收性能

以聚苯乙烯(PS)包覆油酸修饰过的纳米Fe3O4为磁核,在低温(90℃)、中性(pH=7左右)条件下,制备了以PS为惰性隔离层的磁载TiO2光催化剂.用X射线衍射仪(XRD)、透射电子显微镜(TEM)、傅里叶红外分光光度计(FT-IR)、振动样品磁强计(VSM)对催化剂的物相组成、形貌、表面性质、磁学性质进行了表征.以苯酚为模拟污染物,考察了其光催化活性,以自制的磁回收装置,考察其回收特性.结果表明,低温制备的TiO2为锐钛矿结构,平均粒径为2～5 nm,催化剂TiO2/PS/Fe3O4[其中物质的量比为n(TiO2)∶n(St)∶n(Fe3O4)=60∶2.5∶1]具有结构完整的壳/壳/核结构,TiO2在PS/Fe3O4表面负载牢固;光催化降解苯酚遵循一级反应动力学方程,TiO2/PS/Fe3O4[n(TiO2)∶n(St)∶n(Fe3O4)=60∶2.5∶1]的反应速率常数K=0.025 8,与纯TiO2的活性接近(K=0.026 2);循环使用5次后,反应速率常数仅降低0.003 4.所制催化剂具有较强的磁感应强度,平均回收率可达到92%以上.该低温水解法制备的磁载TiO2光催化剂具有良好的应用前景.

Low-Temperature Preparation of TiO2/PS/Fe3O4 and Its Photocatalytic Activity and Magnetic Recovery

This study reports the fabrication of magnetically responsive titania catalyst,which consisted of a magnetic core surrounded by a titania shell.The magnetic core(oleic acid-modified Fe3O4 nanoparticles) was modified with polystyrene as inert isolating layer.The magnetic photocatalyst was prepared at low temperature(90℃) and a neutral pH(about 7).The phase composition,morphology,surface properties and magnetic properties of the composite particles were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),fourier infrared photometer(FT-IR) and vibrating sample magnetometer(VSM).The photocatalytic activity of the samples were determined by degradation of phenol and their recovery characteristics were determined by a self-regulating magnetic recycling equipment.The results illustrated that the mean diameter of anatase titanium dioxide synthesized at low temperature was 2-5 nm,the catalyst TiO2/PS/Fe3O4[the molar ratio of the magnetic photocatalyst was n(TiO2)∶n(St)∶n(Fe3O4)=60∶2.5∶1] had the structural integrity of shell/shell/core,and titanium dioxide was loaded firmly on the PS/Fe3O4 surface.The photocatalytic degradation of phenol followed first-order reaction kinetics and the reaction rate constant K of the TiO2/PS/Fe3O4[n(TiO2)∶n(St)∶n(Fe3O4)=60∶2.5∶1] was 0.025 8,which was close to that of pure TiO2(K =0.026 2).After 5 times recycling,the K value reduced only by 0.003 4.The catalyst had a strong magnetic induction,and the average recovery rate reached 92%.The magnetic TiO2 photocatalyst prepared by this low-temperature hydrolysis method has a good application prospect.