Electrophotocatalytic decolorization of an azo dye on TiO ₂ self-organized nanotubes in a laboratory scale reactor

It was investigated the feasibility of decolorization of an azo dye (DG 26) using a large scale nanotubular TiO ₂ structured electrode in a laboratory photoelectrochemical reactor (0.8L). Catalyst was grown by anodic oxidation directly on Ti surface and its microstructure and crystalline structure were characterized with SEM and XRD. TiO ₂/Ti photoactivity under different anodic polarization values was evaluated via photoelectrochemical tests. The nanostructured TiO ₂ was used in a reactor as photo-anode under UV monochromatic irradiation (254nm) and it was subjected to bias (+1.5V vs. SCE). A comparison with photolysis and photocatalysis processes was carried out under the same operating conditions to evaluate the synergistic action of photocatalysis and TiO ₂/Ti electrochemical polarization. Electrophotocatalysis was proven to be more effective than photocatalysis in DG 26 decolorization. Catalyst polarization resulted in synergistic effect on process yields. The complete decolorization of a 40. mg/L solution of DG 26 was achieved in 24. h, without adding chemical reagents, and catalyst durability was demonstrated over 360. h tests. Therefore, the work done is challenging to prove that the process (irradiation. +. catalyst. +. polarization) is feasible and effectively up-grading to pilot and demonstrative scale applications after a fluid dynamics optimization of the photoreactor.