Ti plate with TiO2 nanotube arrays as a novel cathode for nitrate reduction

Abstract

The purpose of this research is to investigate the possibility of using a Ti plate with TiO₂ nanotube arrays as a novel cathode for nitrate reduction. TiO₂ nanotube arrays were grown on a Ti plate by anodization in a glycerol based electrolyte and annealed to change their crystallographic structure. Morphological and crystallographic structures of Ti plates with a TiO₂ nanotubular layer were analysed before and after anodization or annealing by using energy-dispersive spectroscopy, Brunauer-Emmett-Teller analysis and X-ray diffraction. Cyclic voltammetry and electrochemical impedance spectroscopy were also performed to test the electrochemical reactivity towards nitrate reduction. A lab-scale electrochemical reactor with a RuO₂/Ti anode and a Ti plate with a TiO₂ nanotubular layer as a cathode was operated to treat synthetic wastewater containing up to 600 mg L^-1 of NO₃-N. The Ti plate with a TiO₂ nanotubular layer was compared with other cathodes such as Ti, Cu, Ni, and Stainless Steel. The Ti plate with an anatase TiO₂ nanotubular layer with a layer thicknesses greater than 45 μm was able to show the most efficient nitrate reduction.

Keywords: Anodization; Electrochemical reduction; Electrolysis; Nitrate reduction; TiO(2) nanotube.