Dual electrodes degradation of Amaranth using a thin-film photocatalytic reactor with dual slant-placed electrodes.

A dual slant-placed electrodes thin-film photocatalytic (PC) reactor was proposed and successfully applied to degrade Amaranth. In this PC reactor, both the TiO2/Ti photoanode and the Cu cathode are slant-placed in the reaction chamber, and aqueous thin-film formed on the surface of both electrodes as wastewater flowed over them. The degradation efficiency was significantly improved as a result of additional degradation at the cathode. When the TiO2 photocatalyst was irradiated with UV light, photogenerated electrons were spontaneously transferred from the anode to the cathode, driven by the electric field self-generated between the TiO2/Ti anode and the Cu cathode, based on the principle of establishing a Schottky barrier. On the Cu cathode surface, the transferred photoelectrons either reacted with dissolved oxygen to form H2O2, which then oxidized the dye, resulting in indirect oxidation decolourization, or reacted with the dye, resulting in direct reduction decolourization. The colour removal efficiency of the cathode was about half that of the photoanode. These processes together with direct oxidation of the photogenerated holes on the photoanode gave dual electrode degradation of the dye, and the degradation efficiency was significantly improved.