Using an Innovative Concentric Cube Electrochemical Reactor for High-Efficiency H ₂ O ₂ Production and Atrazine Degradation

This study reports the optimization of a continuous-flow electrochemical reactor with concentric cube geometry designed for the in-situ production of hydrogen peroxide (H2O2). The system, developed using a Printex L6 carbon-based gas diffusion electrode (GDE), was optimized and applied for high-efficiency H2O2 generation and the remediation of atrazine (ATZ) contaminated water. The initial analysis of different volumetric flow rates (200, 400, and 800 mL min–1) showed that the rate of 400 mL min–1 offered the best balance between H2O2 production efficiency, energy consumption (7.57 kWh kg–1), and current efficiency (78.1%). A central composite rotatable design (CCRD) was applied for the analysis of the effects of current density, electrolyte concentration, oxygen flow rate, and pH. The CCRD model exhibited high predictive accuracy (R2 > 0.96), with current density and pH identified as the most influential factors. With a working volume of 1 L, under optimal conditions (0.075 mol L–1 K2SO4, 20 mA cm–2, 0.05 L min–1 O2, pH 5), 848 mg L–1 of H2O2 were generated in 30 min. Among the oxidative processes tested, the combined AO/e-H2O2/UVC treatment recorded >90% ATZ removal and >23% mineralization in 30 min, evidencing a strong synergistic effect attributed to UVC-induced H2O2 photolysis and hydroxyl radical formation. LC-MS/MS analysis confirmed the formation of 11 oxidative intermediates, where the degradation pathways were found to involve dechlorination, N-dealkylation, and cleavage of the s-triazine ring. The results of this study highlight the application potential of innovative reactor designs for efficient H2O2 electrogeneration and sustainable mitigation of persistent organic pollutants.