Photocatalytic Oxidation of Ketoprofen in Water by Silver-Potassium Hexatitanate Co-catalyst
摘要
Potassium hexatitanate K2Ti6O13 material was successfully synthesized by the sol-gel method. Silver was incorporated in different concentrations from 0.1 to 0.7 wt% by photo-deposition method. The Ag-K2Ti6O13 composites were characterized by XRD, SEM, EDX, N2 physisorption, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and Mott-Schottky electrochemical test. The X-ray diffraction analysis showed an almost pure monoclinic crystalline phase of the K2Ti6O13 with a preferential orientation in the plane (3 1 −1). Morphological characterization showed non-well-defined rod particles. The band-gap value for all the materials was 3.35 eV, while PL spectra showed a lower recombination rate of the photogenerated charges in Ag-KTO materials. The point of zero charge was also determined, resulting in pH values of 7.2 and 8.4 for K2Ti6O13 and Ag-K2Ti6O13 respectively. Catalysts with a lower content of silver show a higher density of positive holes generated with the irradiation of the semiconductor, consequently, these materials exhibited better photocatalytic activity towards the ketoprofen degradation. The results indicate that ketoprofen was completely degraded on 30 min of reaction generating several intermediate organic products that reached a maximum at 15 min, and 82% of all the organic compounds were mineralized in 5 h of reaction.