Ionic Liquid And Surfactant-assisted Preparation Of Mesoporous TiO₂/Montmorillonite Nanocomposite And Its Performance Study

Recently, growing attention is given to Pharmaceuticals and personal care products (PPCPs) as emerging contaminants. Researches have indicated that conventional treatment process could not effectively remove PPCPs from water. In contrast, the photocatalysis oxidation and some other advanced oxidation process are much more preferred.Tinanium dioxide (TiO2) is regarded as the best photocatalyst. However, nano-scaled TiO2particles easily agglomerate into larger ones, reducing the catalytic activity. Immobilization of nano TiO2particles on clay minerals such as montmorillonite has been comfirmed to be an effective way to solve the problem of aggregation. Many prior literatures have proposed to prepare TiO2-pillared clay by intercalating positively charged titanium hydrate to the interlayers of montmorillointe. However, TiO2particles are poor distributed on the internal surface with low crystallinity and only limited amount of organic pollutants can be adsorbed to the surface of TiO2photocatalysts owing to the hydrophilicity of montmorillonite.This work is targeted to design a new way of immobilization of mesoporous TiO2on montmorillonite surface via self-assembly method. Firstly, hydrophobic ionic liquid (IL)[Bmim][PF6] and nonionic surfactant Tween80(TW80) were employed to prepare mesoporous TiO2sol. The growth of TiO2crystal was regulated by the mixed micelles formed by IL and TW80. Then, the synthesized TiO2sol was diluted by ethanol and added to montmorillonite suspension to produce TiO2/MMT composites. During the pocess, ionic liquid was intercalated to the interlayer of MMT via ion-exchange reaction, leaving the clay surface hydrophobic. The TiO2nanoparticls, which were connected to the hydrophilic groups of TW80, were deposited on the surface of MMT through the hydrophobic chain of TW80. The synthesized composites exhibited high degree of crystallinity and well distribution of mesopores. As the thermal stability of the composites was improved by ionic liquid, the variations of crystal size, crystalline form and mesoporous structure were controlled during calcination.The synthesized mesoporous TiO2/MMT composites were applied for the adsorptive and photocatalytic degradation of bezafibrate, one kind of typical PPCPs. The degradation efficiency reached up to99.5%, superior to that of the commercial P25-titanium dioxide.