Photocatalytic degradation of a model textile dye using Carbon-doped titanium dioxide and visible light

Rhodamine B (RhB), a dye widely used in the textile manufacturing, contributes with other dyes to harm the environment. Here, with the final goal to provide new tools for the removal of dyes from water, visible light activated carbon-doped titanium dioxide was used to investigate on the decolourization and the photocatalytic degradation of RhB dye from water solutions. The photodegradation activity was tested varying the initial concentration of RhB and the amount of carbon-doped titanium dioxide, taking into account the ratio between the amount of catalyst and the amount of RhB (TiO2/RhB), thus obtaining a parameter that allows the method to be scaled up without losing its effectiveness. Values of k2 and t0.5 were obtained by fitting kinetics data to a second-order kinetic adsorption model. The important role played by doped TiO2 particles is demonstrated by the highly efficient color removal obtained during the visible light-induced photocatalysis. The presence of different degradation intermediates was demonstrated by means of UV–vis Absorption and Fluorescence spectroscopy. Such results underline that the whole photodegradation process does not end with the decolourization occurrence.