Synthesis of Highly Ordered Mesoporous Silica (SBA-16) to Support Titania (TiO2) Nanoparticles for Enhancing the Degradation of Diuron Herbicide

Abstract

In this study, highly ordered mesoporous silica (SBA-16) were synthesized by a one-step sol–gel method, relating to the interaction with the self-assembly of the non-ionic surfactant, pluronic F127 under an acidic condition without the hydrothermal process. SBA-16 was further incorporated with titanium dioxide (TiO₂) with varied Si/Ti ratios (11.2, 2.8 and 0.7) to optimize a suitable condition for producing SBA-16/TiO₂ composites. After calcination, the composites were characterized by using various techniques to evaluate pore characteristics, morphologies and phase present. Typically, the highly ordered porous structure of the synthesized SBA-16 was confirmed by low angle X-ray analysis (LAXRD) and N₂ adsorption isotherms. TiO₂ nanoparticles were found at the surfaces of SBA-16 of each composite based on the HR-TEM images. Diuron herbicide in aqueous solutions (50 ppm of the initial concentration) was used as a polluted model for studying on the photocatalytic activity of the composites under an artificial UV illumination for 24 h. Experimental results revealed that SBA-16 could assist on diuron reduction in the dark condition by the adsorption process. Diuron in the solutions were fully degraded by the synthesized TiO₂ and the SBA-16/TiO₂ composite (0.7 Si/Ti ratio) within 24 h of the UV illumination. In addition, it revealed that SBA-16 could assist on diuron reduction in the dark condition by the adsorption process. The degradation was calculated and followed to the first order kinetic model. Finally, a mechanism of the degradation was discussed and proposed.