Highly dispersed CoFe2O4 spinel on biomass-derived 3D porous carbon framework for much enhanced Fenton-like reactions

Abstract

Rational design of the low-cost, highly efficient and easily recyclable catalyst to directly activate peroxymonosulfate (PMS) is crucial for the efficient removal of organic pollutants in the sewage treatment. Herein, hyperdispersed CoFe2O4 spinel nanoparticles were successfully in-situ fabricated on biomass-derived 3D porous carbon framework (C) by the facile one-step solvothermal method (CoFe2O4/C). These as-prepared CoFe2O4/C exhibit superior performance in the Fenton-like removal of four quinolones by the combination of experimental work and theoretical calculation. Experimental results prove that CoFe2O4/C catalyst can directly activate PMS to efficiently remove four types of quinolones in 12 min without the external energy consumption. The characterization results show that hyperdispersed CoFe2O4 (18.0 ± 5.0 nm) nanoparticles are uniformly anchored on the matrix of C, exhibit a large specific surface area of 733.1 m2/g, and present rich oxygen vacancies (Ovs), thus exposing more reactive sites and generating more reactive oxygen species (ROS). In CoFe2O4/C + PMS system, ∼97.5% of ciprofloxacin (CIP) is removed within 12 min, which is far superior to other candidates previously reported. Other quinolones (e.g., ∼96.8% of ofloxacin (OFL), ∼100% of levofloxacin (LEV), and ∼86.4% of norfloxacin (NOR)) can also be efficiently degraded under the same conditions. Based on quenching experiments, electron spin resonance spectroscopy (ESR), and density functional theory (DFT) calculations, these superior activities are mainly due to the free radical (SO4·-, ·OH, and ·O2–) and non-free radical (1O2), whereas SO4·- and ·OH are the major reactive oxygen species. In addition, these CoFe2O4/C catalysts remain stable even after five cycles. Subsequently, degradation pathways are rationally proposed. This work provides a feasible and universal strategy for the direct activation of PMS in wastewater treatment.