Electrolytic characteristics of ammonia oxidation in real aquaculture water using nano-textured mono-and bimetal oxide catalysts supported on graphite electrodes

• DOI: 10.1016/j.electacta.2020.136990
• Publication Date: 2020-09-02T12:33:59Z
• Authors: Yu-Jen Shih; Shih-Hsuan Huang; Ching-Lung Chen; Cheng-Di Dong; Chin-Pao Huang
• Keywords: Bimetal; Cobalt oxide

Abstract Electrodes were made by electrochemically deposition of mono-metal (Sn, Mn, Pb, and Co) and bimetal (Co-Zn and Co-Ni) oxides on graphite support using metal tartrate precursor in alkaline solution (pH 12). Results of XRD, XPS, and SEM analyses indicated that the nano-textured oxides were consisted of mineral phases, namely, cassiterite (SnO2), birnessite (δ-MnO2), and plattnerite (β-PbO2), and spinel-type cobalt oxides (Co3O4, ZnCo2O4, and NiCo2O4). Cobalt oxide electrode exhibited high chlorine yield because of improved electrical capacitance and transfer coefficient. The rate of chlorine evolution on CoO/G, CoZnO/G, and CoNiO/G electrodes was >2 × 10−4 min−1, which was almost one order magnitude greater than that of other mono-metal oxides (3–8 × 10−5 min−1). The removal of ammonia nitrogen was > 90% under breakpoint chlorination for the treatment of real aquaculture wastewater ([NH4+] ≈ 3 mg-N/L or 2.1 × 10−4 M, [Cl−] = 0.37 M, current density = 3.5 mA/cm2).