A novel CoOOH/PTFE catalytic membrane for persulfate activation to sustainably degrade 17α-ethinylestradiol: Oxygen vacancies promote synergistic pathways of radical and nonradical mechanisms

Peroxymonosulfate (PMS)-based advanced oxidation processes (PMS-AOPs) currently face issues regarding transition-metal ion valence conversion and practical application in water treatment. To address them, we synthesized a CoOOH catalyst with a unique three-dimensional porous flower-like morphology for PMS activation to degrade 17α-ethinylestradiol (EE2) in wastewater. By adding PMS to CoOOH in small amounts, 95.68 % of EE2 (3 mg/L) was degraded within 9 min. The catalytic efficiency of CoOOH was considerably higher than those of a material synthesized via the conventional precipitation method and commercial Co 3 O 4 . CoOOH also exhibited a wide pH adaptability range, good cyclic stability, and a low cobalt ion leaching concentration. It demonstrated excellent PMS activation performance, chemical stability, and safety. Mechanistic studies revealed that numerous surface hydroxyl groups and abundant oxygen vacancies in CoOOH facilitated efficient electron transfer, rapidly achieved the Co 3+ /Co 2+ redox cycle, and generated a large amount of highly oxidative nonradical ( 1 O 2 ) and radical (•O 2 − ) species, thereby efficiently degrading organic pollutants. Finally, by combining PMS-AOPs with membrane separation, a CoOOH/PTFE membrane–PMS system was fabricated for continuous EE2 degradation in lake water; it could operate continuously for 24 h in treating 1.25 L of Dianchi Lake water (Kunming, Yunnan) containing 3-mg/L EE2 while maintaining an EE2 removal rate of 92.35 %. The synthesized CoOOH/PTFE catalytic membrane facilitated transition-metal ion redox cycling and efficient organic-pollutant degradation as well as enabled convenient catalyst recovery, thereby reducing secondary pollution in the degradation process. Overall, this research provides a feasible strategy for the practical application of PMS-AOPs.