Photodegradation of dyes in aqueous solutions catalyzed by highly efficient nanocrystalline titania films

Thin nanocrystalline titanium dioxide films were deposited on glass rings by the sol-gel method in the presence of ethanol, acetic acid and the non-ionic surfactant Triton X-100. Nanocrystallites are formed due to surfactant self-organization that acts as a template. These films have high active surface area and are very efficient for the photodegradation of dyes in aqueous solutions. In addition, the catalyst can be easily recovered and can be repeatedly used without loss of efficiency. Three dyes were used: Basic Blue 41, Acid Orange 7, and Crystal Violet. Decoloration of solutions of Basic Blue is much faster than those of the other two dyes. A very low load of catalyst, i.e. 120 mg 1(-1), is capable of bleaching dilute solutions in only a few hours by shining black light of 0.7 mW cm(-2). An inexpensive and simple reactor of cylindrical symmetry is described which employs a 4 W black-light tube as light source.