Novel integrated reactor for evaluation of activity of supported photocatalytic thin films: Case of methylene blue degradation on TiO2 and nickel modified TiO2 under UV and visible light

In this paper we present an integrated batch reactor for testing of the activity of photocatalysts supported in the form of thin films. The reactor vessel is a custom-built glass cuvette containing the catalyst sample and the solution of a model organic pollutant. The irradiation is provided by a tubular UV lamp or a white LED array fitted to the cuvette lid, while the solution is constantly stirred to minimize external mass-transfer effects. The concentration of contaminant is followed in situ by an integrated photometric system using a low-power laser to match the absorption spectra of model dyes such as methylene blue, reactive black and malachite green. In the current research, the reactor is used to determine the effect of incident radiation on the apparent rate constants of degradation of an organic dye (methylene blue) via thin films of titanium dioxide (Degussa P25) and nickel-modified TiO2. The catalyst performance under various UV and visible light illuminations was estimated using the novel reactor system in just 1 h of experimental time: 30 min of dark adsorption of the dye and 30 min of irradiation. The reactor is suitable for fast screening of the reaction rate of processes utilizing not only titanium dioxide, but also other common photocatalysts and a variety of organic pollutants.