Modified γ-Al2O3 Particle Electrodes Promote Active Chlorine Generation for the Treatment of Hypersaline Organic Wastewater

Electrochemical conversion of chloride to active chlorine is promising for treating chloride-rich organic wastewater, but enhanced oxidant production does not necessarily improve electrical efficiency. Here, Ti–Sn–Sb@γ-Al2O3 particle electrodes were prepared and applied in a flow-through three-dimensional electrocatalytic oxidation (3DEO) system. Modification promoted chlorine evolution while suppressing oxygen evolution. Active chlorine production showed diminishing gains above 30 mA/cm2 and 10 g/L Cl−, whereas increasing flow rate improved production and reduced specific energy consumption. An 80% particle filling ratio provided the highest average generation rate. Initial pH (3–11) had limited influence because the solution became alkaline during electrolysis. For simulated aniline wastewater, 3DEO with NaCl achieved 95.20% aniline and ~47% total organic carbon (TOC) removal, compared with 77.33% aniline removal in the two-dimensional system. Specific energy consumption was ~110 Wh/g TOC, versus 1070 Wh/g with Na2SO4, while TOC-based current efficiency increased from ~11% to ~75%. The laboratory results demonstrate aniline and partial TOC removal. Chlorinated organic by-products and chlorate were not quantified, so effluent safety and practical applicability remain unverified.