Vanadium-Doped Ti4O7 Porous Transport Layers for Efficient Electrochemical Oxidation of Industrial Wastewater Contaminants

Abstract

Inexpensive electrode materials and effective cell designs are needed to advance electrochemical technologies for the oxidative treatment of wastewater. Novel vanadium-doped Ti4O7 porous transport layers (PTLs) used in a compact wastewater electrolyzer are developed and characterized and their performance for the electrochemical oxidation of synthetic wastewater is evaluated. An original analytical model predicting performance with the apparent mass transfer coefficient and cell potential is developed. The influence of operating parameters such as volumetric flow, current density, and PTL composition on performance is investigated. Decolorization and chemical oxygen demand (COD) removal of 100 mg L−1 of methyl orange (MO), an azo dye, in 1,500 mgNaCl L−1 is rapid with mass transfer coefficients as great as 377 ± 24 m s−1 for MO at 15 mA cm−2. After 2.5 Ah L−1 at 10 mA cm−2, >99 decolorization and >98% COD removal are achieved with a current efficiency of 19.2% and with specific and volumetric energy consumption of 120 and 84.1 kWh kg−1 for MO and COD, respectively, and 1.34 ± 0.09 and 6.45 ± 0.97 kWh m−3 order−1, respectively. A more energy-efficient electrochemical cell design for industrial wastewater treatment using less expensive high oxidation power (HOP) electrode materials is demonstrated with these results.