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

• Ti/Sb–SnO2 shows the best performance in Na2SO4 electrolyte.
• Ti/Sb–SnO2/Pb3O4 shows the best performance in NaCl electrolyte.
• Ti/Sb–SnO2/PbO2 shows the best capability to enhance the biodegradability.
• Aniline degradation started by oxidation of amine group and polymer formation.
• The biotoxicity of aniline decreased with electrolysis.

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 (Ep) 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.

Figure optionsDownload as PowerPoint slide