Binary electrochemical mineralization of heterocyclic nitrogenous compounds: parametric optimization using Taguchi method and mineralization mechanism

Electrocatalytic oxidation of aromatic amine (4-aminobiphenyl): Kinetics and transformation products with mechanistic approach

Electrocatalytic oxidation (EO) of carcinogenic 4-aminobiphenyl (4-ABP) aromatic amine was performed using Ti-RuO₂ anodes. Current (I), pH, electrolysis time (t), and 4-ABP initial concentration (C_o ) were selected as EO parameters, and their effects on %4-ABP removal (R₁ ) and energy consumed (R₂ ) were studied. Experimental design, parameters optimization, and their interaction with responses R₁ and R₂ were performed using response surface methodology. At optimized parameters, %TOC removal and 4-BP mineralization current efficiency (%MCE) were assessed to evaluate the potential of Ti/RuO₂ anodes towards 4-ABP mineralization. Simultaneous TOC and 4-ABP degradation kinetics were also studied to evaluate the competition in 4-ABP mineralization and degradation. Further, UPLC-Q-TOF-MS analysis was performed to identify the 4-ABP transformation products during the EO, and a mechanism describing the EO transformation was proposed. At optimum parameters (I = 1.2 A; pH = 4.0; t = 30 min; C_o  = 30 ppm), responses were found to be R₁  = 60.25%; R₂  = 2.49 kWh/g of 4-ABP removed. %TOC removal and %MCE were 52.4% and 34.2%, respectively. PRACTITIONER POINTS: 4-Aminobiphenyl electro-oxidation (EO) was explored using Ti/RuO₂ anode. Achieved 34.2% mineralization current efficiency, 52.4% TOC and 61.3% TKN removal. Three electro-oxidation transformation products of 4-ABP were detected. 4-Aminobiphenyl was found degrading at ≈1.6 times higher rate than TOC A plausible EO transformation pathway and mechanism was proposed.