Singlet oxygen-dominated peroxymonosulfate activation by coal gangue-supported Co3O4 for alkaline wastewater treatment

This study investigates the use of coal gangue-supported Co 3 O 4 (Co 3 O 4 @CG) as an efficient catalyst for activating peroxymonosulfate (PMS) to degrade phenol under pH 11, aiming to address the challenges of treating alkaline coal chemical wastewater (CCW). The Co 3 O 4 @CG-20 % catalyst exhibited excellent performance, achieving over 95 % phenol degradation within 10 min. Singlet oxygen ( 1 O 2 ) was the dominant reactive species in phenol oxidation. Moreover, the system demonstrated strong resistance to common water matrix ions, although carbonate and phosphate showed inhibitory effects. Gas Chromatography–Mass Spectrometry (GC-MS) analysis revealed hydroxylation and ring-opening pathways of phenol degradation, and toxicity assessment confirmed a significant reduction in the toxicity of intermediates. The heterogeneous catalyst also effectively treated actual CCW, highlighting its potential for large-scale application in CCW treatment, particularly in alkaline environments. • Coal gangue supports Co 3 O 4 , forming an efficient catalyst for PMS activation. • Co 3 O 4 @CG-20 % degrades over 95 % phenol in 10 min at pH 11. • Singlet oxygen was identified as the predominant ROS in Co 3 O 4 @CG-20 %/PMS system. • The possible degradation pathways were analyzed and illustrated.