Novel Co-MOF/GO triggered peroxymonosulfate activation: Insight into singlet oxygen generation mechanism from peroxymonosulfate self-decomposition and secondary radical conversion

• Co-MOF/GO activated PMS could remove BAC in a wide pH range of 3–11. • SO 4 − and OH were identified as critical precursors for 1 O 2 generation rather than DO and O 2 – . • Co (II) and Co (III) act as dominant active sites for PMS attachment. Peroxymonosulfate (PMS)-triggered non-radical pathways have potential for environmental application due to the high activity and pH tolerance of singlet oxygen ( 1 O 2 ). However, the mechanism of 1 O 2 generation remains unclear. Herein, new insights into 1 O 2 generation are discussed based on the postulated precursors of PMS, DO, O 2 – , SO 4 − , and OH with Co-MOF/GO catalyst. According to experimental results and theoretical calculation, Co (II) and Co (III) were identified as dominant active sites for PMS attachment, leading to the simultaneous breakage of S-O and O-O bonds and the generation of SO 4 − , OH, and 1 O 2 . SO 4 − and OH were critical precursors for 1 O 2 generation, while PMS self-decomposition had a small contribution. DO and O 2 – acted more likely as quenchers than vital precursors of 1 O 2 . Results provide in-depth understanding of the mechanism of 1 O 2 generation to broaden the application prospects of PMS oxidation technology.