Interface mechanism of peroxymonosulfate activation by cobalt-copper-ferrite nanoparticles mediated by palygorskite for bisphenol S degradation: A dual-path activation mechanism

Peroxymonosulfate (PMS)-based advanced oxidation processes are perceived as a novel strategy for water purification. However, designing an efficient catalyst with a low metal leaching rate remains challenging. Here, under palygorskite (PAL) mediation, 16%-CoCu_0.4Fe_1.6O₄@PAL (16%-CCFO@PAL) was constructed, exhibiting ample oxygen vacancies (V_O) and low metal leakage. The V_O was confirmed by systematic characterizations and theoretical calculations. The catalyst showed the efficient catalytic capacity for PMS by dual-path (i.e., metal sites and V_O) activation. Large amounts of SO₄^•-, •OH, and ¹O₂ were produced, greatly destroying bisphenol S (BPS). BPS removal was greater than 99% within 25 min in the 16%-CCFO@PAL/PMS system. At the metal sites, PMS was activated under the synergistic effects of Co(II)/Co(III), Fe(II)/Fe(III), and Cu(I)/Cu(II) pairs and electron transfer. In addition to metal sites, the V_O was also an activation center for PMS, which mainly captured the O_I atom in [H-O_I-O_II-SO₃]^-, donating an electron to O_I and promoting SO₄^•- generation. The interfacial reaction mechanism was explored by in situ tests, and a dual-path activation mechanism was proposed. This work provides a new perspective for V_O-assisted PMS activation for water treatment.