(641b) Mechanistic Study On the Electrochemical Decolorisation of Rhodamine 6G Using RuO2 Coated Ti DSA

In this study, the performance of electrochemical treatment of Rhodamine 6G containing water by using RuO₂ coated Ti mesh DSA is evaluated, as well as the mechanism of decolorisation process is explored. The effects of solution pH, temperature and addition of auxiliaries on the electrochemical process were examined. Results show solution pH and temperature play import roles during the electrochemical treatment of Rhodamine 6G containing water. Lower solution pH and lower temperature facilitate the decolorisation of the dye-containing water. The addition of auxiliaries dose not significantly effect the electrochemical decolorisation of the dye-containing water. Under optimal experimental condition, complete decolorisation of the dye-containing water can be obtained within 5 min. The electrochemical process can achieve 40.6 and 37.3% mineralization of Rhodamine 6G solution without and with auxiliaries within 5 min, respectively. It was found that water-insoluble foam product formation and mineralization of the Rhodamine 6G were involved during the electrochemical decolorisation of the dye-containing water. Total organic carbon, total nitrogen mass balance analyses, UV-Vis, FTIR and XPS spectroscopy were used to explore the mechanism of the electrochemical decolorisation process. UV-Vis spectra analysis shows the foam product has different molecular structure from Rhodamine 6G. FT-IR, XPS, carbon and nitrogen analyses indicate: amine and methyl groups are first detached from the dye molecule, which changes the dye from polar into non-polar and results in formation of water-insoluble substance; then partial of the water-insoluble substance are floated by the hydrogen bubble generated on cathode, and the others in the solution are further mineralized via aromatic opening and oxidizing. A conceptual model for the electrochemical decolorisation is proposed to illustrate the mechanism.