Deciphering the\nNovel Picolinate-Mn(II)/peroxymonosulfate\nSystem for Sustainable Fenton-like Oxidation: Dominance of the Picolinate-Mn(IV)-peroxymonosulfate\nComplex

A highly efficient and sustainable water treatment system\nwas developed\nherein by combining Mn(II), peroxymonosulfate (PMS), and biodegradable\npicolinic acid (PICA). The micropollutant elimination process underwent\ntwo phases: an initial slow degradation phase (0–10 min) followed\nby a rapid phase (10–20 min). Multiple evidence demonstrated\nthat a PICA-Mn(IV) complex (PICA-Mn(IV)*) was generated, acting as\na conductive bridge facilitating the electron transfer between PMS\nand micropollutants. Quantum chemical calculations revealed that PMS\nreadily oxidized the PICA-Mn(II)* to PICA-Mn(IV)*. This intermediate\nthen complexed with PMS to produce PICA-Mn(IV)-PMS*, elongating the\nO–O bond of PMS and increasing its oxidation capacity. The\nprimary transformation mechanisms of typical micropollutants mediated\nby PICA-Mn(IV)-PMS* include oxidation, ring-opening, bond cleavage,\nand epoxidation reactions. The toxicity assessment results showed\nthat most products were less toxic than the parent compounds. Moreover,\nthe Mn(II)/PICA/PMS system showed resilience to water matrices and\nhigh efficiency in real water environments. Notably, PICA-Mn(IV)*\nexhibited greater stability and a longer lifespan than traditional\nreactive oxygen species, enabling repeated utilization. Overall, this\nstudy developed an innovative, sustainable, and selective oxidation\nsystem, i.e., Mn(II)/PICA/PMS, for rapid water decontamination, highlighting\nthe critical role of in situ generated Mn(IV).