Superior photocatalytic removal of metamitron and its mixture with Rhodamine B dye using combustion synthesized TiO2 nanomaterial

In this study, photocatalytic degradation of a herbicide, metamitron, was carried out using combustion synthesized nano-TiO2. The synthesized catalyst was characterized using X-ray diffraction, porosimetry and UV-diffuse reflectance spectroscopy. The combustion synthesized catalyst showed lower crystallite size, better surface area and narrower band-gap compared to the commercial TiO2. The effect of catalyst loading, initial concentration of metamitron, pH and presence of inorganic ions on the extent of degradation was studied. The pseudo first order rate constant of metamitron degradation using combustion synthesized TiO2 was 1.5-2.5 times higher than that using commercial TiO2 at different initial concentrations of metamitron. The effect of another component, Rhodamine-B dye, on the degradation of metamitron was also probed in this study. The rate of degradation of both metamitron and Rhodamine B were high when the combined system was treated. The degradation by-products were tracked using liquid chromatograph/mass spectrometer, and a possible degradation pathway is proposed.