Photocatalytic Activity of Aeroxide TiO2 Sensitized by Natural Dye Extracted from Mangosteen Peel

Abstract

Natural dye sensitizers are environment-friendly and inexpensive substances that could be used for photocatalytic decontamination of organic pollutants. In this study, a natural dye extracted from mangosteen peel, containing a significant amount of anthocyanin dye, has been successfully employed to sensitize aeroxide TiO2 to lower its bandgap, thereby making the process visible sunlight-driven. We have demonstrated the photocatalytic activity of mangosteen dye-sensitized-TiO2 (MS-TiO2) under visible solar light by studying the degradation of methylene blue (MB), a well-studied model compound. A multivariate parametric study was performed using factorial design methodology with three factors—pH, MS-TiO2 dosage, and visible light intensity. The study indicated that pH and MS-TiO2 dosage are the two most dominant factors for MB degradation under visible solar light. The kinetic rate constant and adsorption equilibrium constant were determined, and a Langmuir-Hinshelwood-type equation was proposed to describe MB degradation on MS-TiO2 under visible solar light. Apparent quantum yield was also reported for the MS-TiO2 photocatalyst at optimum experimental conditions.