Photodegradation of benzoic acid using titanium dioxide catalyst calcined at various temperatures

Abstract

Removing the contaminants from the discharge of industrial, domestic and agricultural wastewater is a great challenge faced by scientists and environmentalists. Therefore, heterogeneous photocatalysis has become emerging technology to mineralize organic pollutants with the use of photocatalyst. In this research, photodegradation of benzoic acid (BA) under 365 nm UV light irradiation for 3 hours was investigated using commercial TiOâ‚‚ P25 Degussa, TiOâ‚‚ Aldrich and TiOâ‚‚ photocatalysts prepared by sol-gel method which were calcined at various temperatures of 450℃, 700℃, 800℃, 900℃, and 1000℃. The photocatalytic activity of the prepared catalysts was assessed by the photodegradation of 1.0x10â»â´ M BA using UV-Vis Spectrophotometer measured at λ_max 227.0 nm. The photocatalytic degradation was also conducted under various experimental condition of calcination temperature, initial concentration of substrate, oxidizing agent, pH and light source. The photodegradation efficiency decreased with the increased of calcination temperature due to the transformation of anatase to rutile phase. It was found that the degradation rate decreased with increasing initial concentration. Furthermore, only the original pH and addition of Hâ‚‚Oâ‚‚ and Kâ‚‚Sâ‚‚O₈ gave better degradation rates. The photodegradation of BA using sunlight and UV light was comparable. Lastly, the prepared photocatalysts were characterized by XRD, FESEM-EDX and BET surface area analysis. The data obtained proved that TiOâ‚‚ P25 Degussa calcined at 450℃ was the most efficient photocatalyst to degrade 92.08% BA at pH 4.8 with the presence of 57% anatase phase, 44.91 m²/g optimum surface area, fine and uniform particle sizes which closely packed together with 29 – 32 nm average particle size of TiOâ‚‚.