PHOTOELECTROCATALYTIC OXIDATION OF RHODAMINE B IN AQUEOUS SOLUTION USING Ti/TiO₂ MESH PHOTOELECTRODES

Abstract

To further improve the photooxidation techniques for water and wastewater purification, a Ti/TiO₂ mesh electrode, was successfully prepared by anodizing Ti mesh in 0.5 M H₂SO₄ solution. The structural and surface morphology of the Ti/TiO₂ electrode was examined by Raman spectroscopy and scanning electronic microscopy (SEM) respectively. The examination results indicated that its structure and properties were affected by its growth rate in the anodization process, and anatase TiO₂ was dominant in its composition. The photocatalytic (PC) oxidation and photoelectrocatalytic (PEC) oxidation of rhodamine B in aqueous solution using the Ti/TiO₂ electrode were investigated and compared. The experimental results demonstrated that the PEC oxidation by applying an electrical bias between the Ti/TiO₂ electrode and Pt electrode could significantly enhance the degradation rate of rhodamine B compared with the PC oxidation. It was found that the best performance of PEC oxidation was achieved by applying the electrical bias of 0.6 V. The mechanism of rhodamine B degradation in the PEC process was discussed by studying the changes of absorbance spectrum and proton nuclear magnetic resonance spectroscopy of rhodamine B during the PEC degradation. The experimental results illustrated that both de-ethylation and chromogen destruction of rhodamine B under UV-light irradiation in the PEC degradation took place simultaneously.

Keywords:

• Titanium mesh
• Anodization
• Titanium dioxide
• Photoelectrocatalytic oxidation
• Rhodamine B

ACKNOWLEDGMENT

The work described in this paper was substantially supported by a grant from the Research Committee of The Hong Kong Polytechnic University (Project No: G-S714/97).