Mechanochemical anchoring of Co nanoclusters on dolomite: Ultrafast PMS activation for norfloxacin oxidation

Preventing cobalt agglomeration on minerals via a simple route remains a challenge for peroxymonosulfate (PMS) activation. Herein, a one‑step mechanochemical ball‑milling strategy was developed to anchor Co nanoclusters in situ onto natural dolomite (CaMg(CO3)2), yielding a highly dispersed and leaching‑resistant Co@Dol composite. This solvent‑free solid‑state process exploits the intrinsic Ca2+/Mg2+ pairs of the dolomite matrix to accelerate the Co2+/Co3+ redox cycle. As a result, 99.0% of norfloxacin (NFA) was removed within 30 min, accompanied by a remarkably low cobalt leaching concentration of only 0.790 mg/L. Radical quenching tests and EPR (electron paramagnetic resonance) analysis confirmed that SO4•- and 1O2 constituted the dominant reactive oxygen species. The Co@Dol system maintained robust degradation performance over a wide pH range (2.5-11), in the presence of various coexisting anions, and in authentic water matrices, with the removal efficiency remaining over 90% after five consecutive cycles. Furthermore, a catalytic membrane (PVDF/PVP@Co0.5, where PVDF and PVP denote polyvinylidene fluoride and polyvinylpyrrolidone) fabricated by incorporating Co@Dol into a PVDF matrix achieved 96.04% NFA degradation within 30 min. This work provides a scalable and green platform for constructing highly stable, cobalt‑based PMS activators directly from abundant natural minerals.