The Use of Titanium Dioxide-Mediated Photocatalysis in the Treatment of Wastewater

The use of titanium dioxide-mediated photocatalysis to degrade aqueous solutions of rhodamine 6G is described. We use a novel and simple experiment for the photochemical reaction—a desk lamp bulb (60 W) irradiating the dye solution in a beaker. This makes the practical session very easy and cost-effective to implement. Several experimental parameters are described. First, the photo-depletion of the dye as a function of time is monitored using visible spectroscopy. Time-dependent analysis of the spectra gives kinetic information—we measure a rate constant of 1.3 × 10–2 min–1 for degradation of the dye. Second, the effect of concentration of catalyst is investigated. Finally, the effect of addition of hydrogen peroxide to the solution is investigated. The latter two experiments can be used by more advanced students to investigate optimum parameters for degradation, which is caused in the main by hydroxyl radical formation. This practical can be used as either a stand-alone laboratory experiment or an extended mini-project.