Facile synthesis and synergistic mechanism of CoFe_2O_4@ three-dimensional graphene aerogels towards peroxymonosulfate activation for highly efficient degradation of recalcitrant organic pollutants

摘要

Magnetic CoFe_2O_4 is a promising heterogeneous catalyst with great separation and catalytic performance on per-oxymonosulfate (PMS) activation. However, for extremely recalcitrant organic pollutants (e.g. Benzotriazole (BTA)), CoFe_2O_4/PMS system exhibits much low catalytic performance and high metal ion leaching. As such, CoFe_2O_4 supported on three-dimensional graphene aerogels (CoFe_2O_4@3DG) was synthesized via facile hydro-thermal 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 CoFe_2O_4@3DG/PMS system (0.0203 min~(-1)) is 15 times higher than that in the CoFe_2O_4/PMS system (0.0013 min~(-1)). It results from synergis-tic activation of PMS by CoFe_2O_4 and 3DG to generate multiple reactive oxygen species (·OH, SO~-_4·, O~-_2· and ~1O_2). 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 CO_2. NH_3 and intermediates through benzene and triazole ring-opening reactions. Moreover, CoFe_2O_4@3DG/PMS system displays good stabil-ity and recyclability. Therefore, this study provides a new way to improve CoFe_2O_4 activity for extremely recalci-trant organic pollutants degradation and new insights into synergistic activation of PMS by CoFe_2O_4 and 3DG, which further advances cobalt-based catalysts in heterogeneous catalysis.