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

Abstract

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 H₂O_2, 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.

Keywords:

• Dual thin-film photocatalytic reactor
• slant-placed electrode
• self-generated electric field
• Schottky barrier
• Amaranth
• UV light

Acknowledgments

Financial support from the Natural Science Foundation of China (Project Nos. 20937003 and 21077140), Special Fund of State Key Joint Laboratory of Environment Simulation and Pollution Control (Project No. 10K12ESPCT), Three Gorges Reservoir Area Ecological Environment Key Laboratory of the Ministry of Education Visiting Scholar Foundation (Project No. KLVF-2010-4), the Natural Science Foundation of Chongqing Science and Technology Commission (Project Nos. cstc2011jjA0837 and cstc2011jjA0835), Chongqing Education Committee Natural Science Foundation (Project No. KJ110801) and the Key Discipline Project of Chemical Engineering and Technology in Chongqing University of Technology are gratefully acknowledged.