Degradation of 2-(methylamino)benzoic acid and methyl anthranilate using a novel electrochemical trickle-fixed bed reactor without pH regulation

As a high-performance wastewater treatment method, an electrochemical oxidation process has been used to degrade refractory organic pollutants. However, the addition of electrolyte and/or adjustment of pH value would inevitably cause secondary pollution and increase the difficulty of subsequent treatment. The degradation of 2-(methylamino)benzoic acid and methyl anthranilate was investigated using a novel electrochemical trickle-fixed bed reactor, integrated with Sb-doped SnO₂/Ti anodes. In the 2 L reactor, the chemical oxygen demand removal efficiency of 2-(methylamino)benzoic acid and methyl anthranilate was 80% and 60% respectively using 100 mg/L solution within 10 h under 30 V applied voltage without pH regulation. To improve the degradation efficiency and the application probability in actual organic wastewater treatment, a 50 L electrochemical reactor was designed and tested. The experimental results demonstrated that the scaled-up reactor maintained stable COD removal efficiency for 2-(methylamino)benzoic acid, while its energy consumption was controlled at a level suitable for industrial application through optimized multi-electrode arrays and high direct current power supply. This work provides an innovative solution for the deep treatment of toxic aromatic amine-containing wastewater without pH regulation and/or added electrolyte, bridging scalable reactor design with insights into voltage-dependent pathways and the influence of molecular polarity.