A novel method for photodegradation of high-chroma dye wastewater via electrochemical pre-oxidation

A new two-step process involving the electrocatalytic (EC) pre-oxidation and the following photoelectrocatalytic synergistic (PEC) oxidation is proposed to treat the high concentration and high-chroma methyl orange dye wastewater, which cannot be degraded by photocatalytic oxidation (PC) directly. The SnO2/TiO2-NTs/Ti electrode simultaneously possessing the outstanding PC oxidation properties of TiO2-NTs and the excellent EC oxidation abilities of the Sb doped SnO2 was synthesized by impregnating Sb doped SnO2 nanoparticles into TiO2-NTs. In the pre-oxidation process as the first stage, the high-color dye wastewater is decolorized with electrochemical method to some extent. Then, the wastewater becomes a light transmission system. It provides a suitable condition for PC oxidation reaction in the second stage. The synergistic effects of PC and EC oxidation led to the high PEC efficiency and the complete mineralization of dye wastewater is achieved. This two-step process is fast and efficient, which is worthy to study and explore in the practical environmental treatment.