Study on Photocatalytic Peroxone Process for Treating Organic Pollutants in Leachate Based on Modified Carbon Quantum Dots

This study couples a carbon quantum dot photocatalyst with a proton relay installed (EDTA-CQDs) for efficient hydrogen peroxide (H2O2) production with an ozone (O3) system. In situ activation of O3 is achieved by the photogenerated H2O2, which integrates the photocatalytic hydrogen peroxide production (PHP) and advanced oxidation processes (AOPs) to form a new photocatalytic peroxone (H2O2/O3) system, achieving highly efficient solar-driven degradation of recalcitrant organic pollutants in landfill leachate without the addition of external H2O2. The composite system exhibits efficient degradation ability for various typical pollutants in landfill leachate, among which the degradation percentage of 100 mg L−1 hydroquinone (HQ) reaches 97% within 30 min. This is due to the synergistic effects of O3 oxidation, photoactivation of O3, activation of O3 by EDTA-CQDs, and activation of O3 by in situ-generated H2O2. In the EDTA-CQD-based H2O2/O3 system, free radicals can be dynamically regenerated after the addition of pollutants, achieving sustained and efficient degradation. Therefore, in the treatment of actual leachate, the removal percentages of COD, TOC, and UV254 are nearly 90%, 70%, and 55%, respectively, demonstrating the significant advantage of this system in treating high-concentration recalcitrant organic pollutants in wastewater of complex quality.