Singlet oxygen dominated aqueous contaminant remediation by CoZn-ZIF-derived Co-ZnO in visible light/peroxymonosulfate system

The selective conversion of peroxymonosulfate (PMS) to singlet oxygen (¹O₂) critically depends on precise electronic structure engineering of the catalysts. The PMS electron-donating pathway enables ¹O₂ generation, but the high energy barriers associated with the initial intermediate *SO₅^•− formation result in an unsatisfactory ¹O₂ yield. Herein, Co-doped ZnO was designed by calcination of zeolitic imidazolate framework. Co doping significantly improved the visible-light response, enhanced the photogenerated carrier separation and migration of ZnO, and increased the ZnO valence band potential. These effects promoted the electron-donating reaction of PMS to produce ¹O₂. The optimized Co-ZnO-3/vis/PMS system exhibited a 27.2-fold higher methylene blue degradation rate constant (k = 0.9871 min⁻¹) with 43.7% total organic carbon removal within 5 min. In addition, the developed ¹O₂-dominated oxidation system removed 83.1% of chromaticity, 59.9% of total phenol, and 24.8% of chemical oxidation demand from the coking wastewater tailwater. This work provides a pathway for tailoring ¹O₂-dominated reactive species for contaminant removal, providing a theoretical guideline for the deep treatment of coking wastewater tailwater.