Multicomponent Cu-Mn-Fe silica supported catalysts to stimulate photo-Fenton-like water treatment under sunlight

Removal of contaminants of emerging concern (CEC) from water is a serious problem. Using sunlight to assist in this process is one of the most sustainable methods for water treatment. In this study, we demonstrate that tailoring the morphology and optimizing the metal concentration in the multicomponent catalysts through an appropriate synthetic strategy leads to Fenton-like and photo-Fenton-like systems capable of effectively degrading bisphenol A and coumarin as model endocrine disruptors and coumarin as a probe for •OH detection. Multicomponent Cu-Mn-Fe silica supported catalysts were prepared via direct synthesis by incorporating magnetic Fe3O4 nanoparticles, Mn and Cu during the formation of silica nanoparticles with interparticle mesoporosity. Comprehensive characterization by advanced microscopic and spectroscopic techniques revealed qualitatively and quantitatively the presence of magnetic Fe oxides covered with the silica support, isolated Mn cations/oxo species into silica framework and CuO particles attached to the silica framework. The Fenton-like activities of the catalysts are due to the catalytic disproportionation of H2O2 by Cu2+ species and isolated Mn species in the silica support. The investigated catalysts are efficient concerning the homolytic cleavage of H2O2 to hydroxyl radicals, with a further positive effect of hydroxyl radical formation observed under visible-light illumination thus acting as photo-Fenton-like catalysts. Fe oxides with magnetic properties are used for easy separation of the catalyst/photocatalyst after the reaction and do not contribute to the catalytic/photocatalytic performance.