Process Intensification of Tetracycline Degradation: Synergistic Electrocatalytic Ozonation and Photoelectrocatalysis...

The persistence of antibiotics in wastewater necessitates advanced treatment strategies to reduce environmental risk. This study investigates the degradation of tetracycline (TC) using a Ti_0.7Ru_0.3O₂-mixed metal oxide (MMO) anode through electrocatalysis (EC), photocatalysis (PC), ozonation (Oz), and their coupled configurations: photoelectrocatalysis (PEC) and electrocatalytic ozonation (ECOz). Water, methanol, and ethanol were used to evaluate solvent-dependent radical generation and degradation pathways in concentrated antibiotic effluents, simulating real-world postadsorption regeneration scenarios. EC achieved >98% removal in water and methanol but was limited in ethanol (92.5%) due to stable carbon-centered radical formation. Ozonation was highly effective in water (99.3%) but failed in organic media (<8%). In contrast, coupled processes (PEC and ECOz) consistently achieved ∼99% removal across all solvents. Notably, ECOz in water exhibited the highest synergy index (SI = 4.76). Mechanistic analysis via LC-MS identified key intermediates, revealing that while single processes often generated persistent and potentially more toxic byproducts, coupled systems promoted deeper oxidation toward mineralization. Effective energy consumption (EEC) calculations showed that process integration significantly improved kinetic rates, offsetting the additional power requirements. These findings demonstrate that integrating electrochemical AOPs is a robust strategy for treating concentrated antibiotic streams, bridging the gap between pollutant separation and safe environmental discharge.