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

• Excellent water treatment capacity is realized in 16%-CCFO@PAL/PMS system. • The O I atom in PMS ([H-O I -O II -SO 3 ] - ) is mainly captured by oxygen vacancy (V O ). • The existence of V O enhances PMS activation to generate SO 4 •− . • The interfacial reaction mechanism in PMS activation is investigated. • PMS was activated by a dual-path 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 0.4 Fe 1.6 O 4 @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 SO 4 •- , •OH, and 1 O 2 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 -SO 3 ] - , donating an electron to O I and promoting SO 4 •- 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.