Kinetic Studies of Photocatalytic Dye Decomposition over a Supported Metal Oxide Catalyst

Wastes generated by the textile industry contribute to nearly 20% of global water pollution, with azo dyes accounting for over half of the industry. These dyes are characterized by the presence of doubled bonded nitrogen groups, resulting in a complex structured organic dye. Mordant Orange 1 (MO1), also known as Alizarine Yellow R, is an azo dye that is used as a biological stain as well as in dyeing industries. Its release into the environment can lead to cancer in humans as well as promote tumor growth in animals that have been exposed to it through contaminated water. There are numerous means of degradation of such organic dyes, photocatalysis being one of the most effective methods. Semiconductors are chosen to participate in the photocatalytic conversion of the organic dye and are generally chosen based on their physical properties. The selection of an effective metal oxide semiconductor allows for the facilitation of oxidation and reduction processes, leading to the degradation of the dye. Combined metal oxide catalysts are able to separate these processes in order for more effective photocatalytic degradation as well as reduce the recombination effects of the electron-hole sites responsible for carrying out the redox processes.

In this study, we will explore TiO2 and ZnO-based catalysts that can lead to the effective photocatalytic degradation of textile dyes such as MO1. It will utilize the chemical vapor deposition (CVD) technique with Al2O3 used as catalyst support. The physical properties as well as the structure of the catalyst will be tested using characterization techniques (e.g., BET and Raman). The effectivity of the newly synthesized catalysts will be tested with UV irradiation with a pre-stir condition in order to establish an adsorption/desorption of the dye onto the combined catalyst’s surface. Our results indicate that ZnO on its own is ineffective in the degradation of MO1. TiO2 is able to effectively degrade MO1 on its own.