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In this study, TiO2 was immobilized onto a titanium electrode for conducting MTBE degradation in aqueous solution. The TiO2 coated electrode could possess photocatalytic characteristics, and thus the application of the TiO2 coated electrode is able to perform photocatalysis and/or electrolysis under various controls. A bench-scale reactor system consisting of an electrolytic cell, an electrochemical analyzer, an electrical multimeter, and a UV-light source was employed to perform electrochemical experiments and electrophotocatalytic experiments. The results of electrochemical experiments showed that an optimum electrolytic condition was operated at 3.00 V in a 1 M Na2SO4 electrolyte solution, and the initial 20 mg/L MTBE was reduced by 67% within 180 min. Comparatively, the photocatalytic removal of MTBE was only 52% within 180 min. The electrophotocatalytic experiments have demonstrated that the photocatalytic removal of MTBE was raised to 65% as applying a potential at −0.25 V. The recombination of photoinduced electrons and holes could be significantly suppressed because the generated electrons by TiO2 excitation were taken away from the electrode as applying a negative potential. On the contrary, the improvement on MTBE removal is not obvious with the assistance of a positive electrical potential. Even though the mechanisms of electrochemical oxidation and electrochemically assisted photocatalysis to produce radicals for the breakdown of MTBE might be different, both processes followed the identical degradation pathway of forming acetate and CO2 based on the identification of GC/MS. According to the comparison of coulometric efficiency, photocatalysis with the assistance of a slight negative potential is the most effective and efficient approach to treat MTBE contaminated water. |
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