Enhanced peroxone reaction with amphoteric oxide modulation for efficient decontamination of challenging wastewaters: Comparative performance, economic evaluation, and pilot-scale implementation

Abstract

The peroxone reaction, a promising alternative technology for water treatment, is traditionally hampered by its restricted pH operational range and suboptimal oxidant utilization. In this study, we introduced a novel amphoteric metal oxide (ZnO)-regulated peroxone system that transcended the pH limitations of conventional peroxone processes. Our innovative approach exploited the unique properties of ZnO to regulate the reaction pathway of the traditional O₃/H₂O₂ (or peroxymonosulfate, PMS) processes, resulting in a 52.4 % (64.9 %) increase in the removal efficiency of electron-deficient pollutant atrazine under acidic conditions (pH=5.8). This was achieved through the facilitated generation of hydroxyl radicals (^•OH) and sulfate radicals (SO₄^•-), alongside a marked increase in the utilization efficiency of O₃, thus reducing the requisite amount of oxidant. The primary active sites within this system were identified as zinc-oxidant sites, with the critical interfacial interactions between ZnO and oxidants elucidated through comprehensive analytical techniques. These studies reveal that ZnO acted as an electron acceptor, with H₂O₂ (or PMS) serving as the electron donor, leading to the formation of a reactive intermediate. This intermediate subsequently engaged with O₃, producing secondary radicals such as HO₂^• (SO₅^•-) and O₃^•-, which were instrumental in generating the final radical species, ^•OH and SO₄^•-. The efficacy of this ZnO-regulated peroxone process was validated through resistance to interference tests, treatment of pilot-scale coking wastewater (mineralization rate of over 70 %), and extensive biological toxicity evaluations, all of which validated the system's robust degradation capability, stability, and significant detoxification potential. A detailed comparison of reaction systems with conventional technologies using Electrical Energy per Order (EE/O) and Life Cycle Assessment (LCA) further highlighted the advantages. This investigation offers a groundbreaking solution for the treatment of complex wastewater, showcasing the substantial promise of ZnO-catalyzed peroxone for practical wastewater treatment applications.