Photodegradation and aggregation of acridine dyes adsorbed on the surface of mesoporous TiO2 films

Electronic spectroscopy and laser desorption/ionization (LDI) mass spectrometry have been used to study the effects of UV exposure on acridine dyes such as acridine orange (AO) and acridine yellow (AY) adsorbed on the surface of mesoporous TiO 2 films. The main stages of the photodegradation process have been identified. The first one is photooxidative N-demethylation of the dimethylamino group in AO and deamination in AY. The following stages are photodimerization and photoaggregation on the superhydrophilic TiO 2 surface and further photocatalytic decomposition to the completely mineralized dyes.