Sonophotoelectrocatalytic degradation of azo dye on TiO2 nanotube electrode

The degradation of azo dye, methyl orange (MeO) in aqueous solution with sonophotoelectrocatalytic process was investigated. The TiO2 nanotubes were used as electrode in photoelectrocatalytic (PEC), sonophotoelectrocatalytic (SPEC) processes or as photocatalyst in photocatalytic (PC), sonophotocatalytic (SPC) processes, respectively. Experimental results showed that the hybrid processes could efficiently enhance the degradation efficiency of MeO, and followed pseudo-first-order kinetics. At the optimized experimental conditions, the rate constants of decolorization of MeO were 0.0732 min(-1) for SPEC process; 0.0523 min(-1) for PEC process, 0.0073 min(-1) for SPC process and 0.0035 min(-1) for PC process. The rate constants obviously indicated that there existed synergistic effect in the ultrasonic, electro-assisted and photocatalytic processes. (C) 2007 Elsevier B.V. All rights reserved.