Enhanced degradation of bisphenol A over CFO/CMK-3 involved PMS activation: Insights into the synergistic effect between the spinel and mesoporous carbon

Abstract

Here, we prepared ordered mesoporous carbon (CMK-3) coupled spinel CoFe2O4 (CFO) composite catalyst, in which the CFO nanoparticles were uniformly dispersed on the surface of CMK-3. The catalyst was applied for the elimination of bisphenol A (BPA) involved PMS activation. The removal rate was 96 % for CFO/CMK-3 after reaction for 15 min, much higher than that of single CMK-3 (19 %) and CFO (47 %). The CFO/CMK-3/PMS system can efficiently remove BPA in a wide pH range of 3–11 and strong alkaline conditions (pH 11) facilitated the oxidation reaction due to the vital role of surface-bound active species. Quenching experiments and Electron Paramagnetic Resonance (EPR) signals demonstrated that free OH, SO4− and 1O2 were involved in the AOPs of BPA, while the surface-bound active species predominated the degradation. The synergistic mechanism between CFO and CMK-3 could be depicted that CFO increased the electron-rich centers of CMK-3. PMS was activated by Co2+/Co3+ and Fe3+/Fe2+ in CFO and electron-rich centers in CMK-3, respectively, then the adsorbed BPA was degraded by adjacent surface-bound and/or free active species. Besides, the composite catalyst could also act as the electron transfer tunnel favoring charges move from adsorbed H2O/OH− to PMS and resulting in enhanced PMS activation. The coexistent humic acid and NO3− showed slight depression on the reaction while the presence of HCO3− and Cl− facilitated the degradation.