Efficient activation of peroxymonosulfate on CuS@MIL-101(Fe) spheres featured with abundant sulfur vacancies for coumarin degradation: Performance and mechanisms

For improving the catalytic activity and recyclability of CuS in Fenton-like reaction processes, novel sulfur vacancies-enriched [email protected](Fe) was constructed, characterized, and examined as heterogeneous catalysts for activating peroxymonosulfate (PMS) to degrade coumarin (COU). Thanks to the redox pairs of Fe3+/Fe2+, Cu+/Cu2+, S2−/S22−/S0/sulfate species, copper-iron synergistic effect and sulfur vacancies, the [email protected](Fe) realized a complete removal of COU (30 μM) in 10 min with reaction rate constant of 0.577 min−1, which was 11.1 and 17.0 times of CuS and MIL-101(Fe), respectively. The effect of various experimental conditions (i.e., initial pH, [email protected](Fe) dosage, PMS concentration, and background anions) on COU degradation was discussed, and the stability and versatility of [email protected](Fe) was studied as well. Radical scavenging experiments and electron paramagnetic resonance (EPR) spectroscopy identified •OH and 1O2 as the main reactive oxygen species (ROS). Finally, the possible mechanism of higher COU degradation efficiency in the [email protected](Fe) activated PMS system and the degradation pathways were also deeply explored. Consequently, this work provided a novel insight into construction of sulfur vacancies-enriched heterogeneous catalysts for efficiently activating PMS for refractory organic pollutants elimination.