Effect of Cupric Salt Addition on Ozone-Electrolysis Advanced Oxidation Process

This study investigates the enhancement of ozone-electrolysis advanced oxidation process (AOP) through the addition of cupric salts. AOPs are effective for degrading persistent organic pollutants, and the ozone-electrolysis method offers advantages such as reagent-free operation and resistance to UV-absorbing interferences. However, its efficiency is limited by low dissolved ozone concentrations. To address this, cupric ions (Cu2+) were introduced as mediators, operable at higher pH levels than conventional ferrous ion systems. Experiments were conducted using synthetic wastewater containing 1,4-dioxane as a radical probe, with varying pH (3.0 and 5.0) and current densities (2.5–10 mA/cm2). Results showed that Cu2+ addition significantly enhanced 1,4-dioxane degradation during electrolysis, attributed to the generation of hydroxyl radicals (HO•) via reactions between ozone and electrochemically reduced copper species (Cu+ and Cu). The effect was more pronounced at pH 5, due to increased radical generation, while lower performance at pH 3 was linked to suppressed electrochemical reduction of ozone. Post-electrolysis ozonation revealed that deposited copper on the cathode could be corroded and dissolved, further contributing to radical generation and pollutant removal. These findings demonstrate the potential of cupric salts to improve ozone-electrolysis AOP efficiency.