Caffeine degradation using peroxydisulfate and peroxymonosulfate in the presence of Mn2O3. Efficiency, reactive species formation and application in sewage treatment plant water

The crucial role of manganese(III) species in the oxidative and catalytic reactivity manganese oxides have been widely reported. However, direct activation radical precursors by Mn(III) is still a matter discussion. In this work, ability Mn(III)-bearing oxide (Mn2O3) for peroxydisulfate (PS) peroxymonosulfate (PMS) was evaluated compared using caffeine (CAF) as model pollutant. Complete CAF removal achieved with 5 mM PS or PMS after 8 h reaction time, whereas 48% mineralization obtained 70 when used oxidant. Electron paramagnetic resonance spin trapping (EPR) scavenging experiments showed that sulfate (SO4•–) dominant Mn2O3/PMS system. comparison, non-radical mechanism such Mn2O3 surface-activated promoted system Mn2O3/PS. Liquid chromatography coupled to mass spectrometry analyses enabled detection main degradation products proposition pathways. Investigations real sewage treatment plant water decrease observed wastewater pure can be alleviated increasing dosage. These findings highlight great Mn-species different matrices, which important implications development novel technologies.