Electrocatalytic degradation of aniline by Ti/Sb-SnO₂, Ti/Sb-SnO₂/Pb₃O₄ and Ti/Sb-SnO₂/PbO₂ anodes in different electrolytes

Electrochemical treatment (ECT) of bio-refractory and highly toxic aniline was investigated over Ti/Sb-SnO₂, Ti/Sb-SnO₂/Pb₃O₄ and Ti/Sb-SnO₂/PbO₂ anodes in Na₂SO₄ or NaCl electrolyte, for the purpose of finding out the most suitable electrode in the two kinds of electrolyte. The degradation performances of aniline were investigated by UV-Vis spectra, chemical oxygen demand (COD) and biochemical oxygen demand (BOD). In addition, instantaneous current efficiency (ICE) and energy consumption (E_p) for aniline degradation were also studied. Results showed that the performances of aniline electrochemical oxidation at the three electrodes were significantly different, which also relied on the electrolytes. Ti/Sb-SnO₂ showed the best effect on the degradation of aniline in Na₂SO₄ electrolyte. The aniline and COD removal efficiency could achieve 95.9% and 91.1%, respectively, at the lowest energy consumption after 5 h electrolysis. While Ti/Sb-SnO₂/Pb₃O₄ was more capable in NaCl electrolyte. The aniline and COD removal efficiency could achieve 97.7% and 96.8%, respectively, at the lowest energy consumption after 5 h electrolysis. Ti/Sb-SnO₂/PbO₂ had the best capability to enhance the biodegradability in the both Na₂SO₄ electrolyte and NaCl electrolyte. The biodegradability (BOD₅/COD) could be promoted from original 0.286 to 0.498 and 0.452, respectively. Moreover, it was found that the wastewater biotoxicity was also an important parameter to study the enhance biodegradability besides the effect of ring-opening or bond breaking. Furthermore, a simple mechanism of aniline degradation was proposed.