Electronic modulation of fiber-shaped-CoFe2O4 via Mg doping for improved PMS activation and sustainable degradation of organic pollutants

As an ideal electron donor, the doping of Mg in CoFe2O4 (MCFO-0.4) endows Co site with electron-rich character, which exhibits enhanced capability and high stability for PMS activation to generate 1O2 and OH radicals, thus achieving outstanding activity, reusability and low metal leaching during Ponceau 2R degradation process. [Display omitted] •Mg-doped CoFe2O4 (MCFO-0.4) were synthesized via a simple sol-gel strategy.•Mg acts as an electron donor endows Co sites with electron-rich property.•Outstanding activity and low metal leaching were achieved in MCFO-0.4/PMS system.•MCFO-0.4 was highly stable and effective in multiple cycles of Ponceau 2R degradation process.•1O2 and OH radicals were involved in the catalytic oxidation process. Advanced oxidation processes (AOPs) driven by transition metal oxides are promising systems for the removal of organic pollutants. However, the catalytic activity is still limited by the low redox property of the active site. In this study, a novel and robust fiber-shaped cobalt ferrite catalyst was synthesized through a magnesium doping strategy. Detailed structural characterization and theoretical calculations demonstrated that the doping of Mg into CoFe2O4 maintains the spinel structure but increased the electron density of Co sites due to its similar atomic radius but different electronegativity to Co. Remarkably, the optimized MCFO-0.4 achieved superior capability for peroxymonosulfate (PMS) activation and outstanding performance for the catalytic degradation of Ponceau 2R (PR). Furthermore, the inherent crystal stability and magnetic nature of spinel allows for magnetically reusability and ultra-low cobalt leaching of MCFO-0.4. Radical quenching and EPR results confirmed the involvement of singlet oxygen and hydroxyl radicals during PMS activation, and a possible catalytic mechanism was finally proposed. This work provides a case study on microstructural regulation and electron modulation in spinel catalysts, which may provide now clues to further improve the activity of oxidation catalysts for large-scale wastewater treatment.