Facile synthesis and synergistic mechanism of CoFe2O4@three-dimensional graphene aerogels towards peroxymonosulfate activation for highly efficient degradation of recalcitrant organic pollutants

Abstract

Magnetic CoFe2O4 is a promising heterogeneous catalyst with great separation and catalytic performance on peroxymonosulfate (PMS) activation. However, for extremely recalcitrant organic pollutants (e.g. Benzotriazole (BTA)), CoFe2O4/PMS system exhibits much low catalytic performance and high metal ion leaching. As such, CoFe2O4 supported on three-dimensional graphene aerogels (CoFe2O4@3DG) was synthesized via facile hydrothermal method. It turns out that 3DG as supporter significantly enhances specific surface area, redox activity and electron transfer of composite. The degradation rate constant in the CoFe2O4@3DG/PMS system (0.0203 min−1) is 15 times higher than that in the CoFe2O4/PMS system (0.0013 min−1). It results from synergistic activation of PMS by CoFe2O4 and 3DG to generate multiple reactive oxygen species (•OH, SO4−•, O2−• and 1O2). Particularly, high graphitization structure and low oxygen groups content of 3DG facilitate PMS adsorption on its surface and electron transfer from BTA to PMS. Ultimately, BTA is degraded into CO2, NH3 and intermediates through benzene and triazole ring-opening reactions. Moreover, CoFe2O4@3DG/PMS system displays good stability and recyclability. Therefore, this study provides a new way to improve CoFe2O4 activity for extremely recalcitrant organic pollutants degradation and new insights into synergistic activation of PMS by CoFe2O4 and 3DG, which further advances cobalt-based catalysts in heterogeneous catalysis.