Photocatalytic Degradation Kinetics of Congo Red dye in a Sonophotoreactor with Nanotube TiO 2

Abstract

TiO₂ nanotubes were prepared by anodisation of Ti sheets using the conventional electrochemical technique as well as an emerging sonoelectrochemical technique. Scanning electron microscope analysis showed that ultrasound-assisted anodisation yielded more ordered and controllable TiO₂ tube banks with higher tube diameter. TiO₂ nanotubes prepared using the sonoelectrochemical method were used in the sonophotocatalytic degradation experiments of Congo Red dye and degradation kinetics were obtained. The effects of temperature and the amplitude of ultrasound energy were investigated and a kinetic equation, which also included the effect of ultrasound energy, was developed. The sonophotocatalytic degradation rate was found to be –r_dye = k_a C_dye /(1 + k_bC_dye). The ultrasound energy did not influence the activation energy. It was observed that the reaction rate accelerated in the presence of ultrasound energy in the course of the experiments. The activation energy of the reaction was calculated to be 56.1 kJ mol^–1.