Synergistically enhanced heterogeneous activation of persulfate for aqueous carbamazepine degradation using Fe3O4@SBA-15

The exploration of low-cost, high-performance and stable catalytic materials for sulfate radical-based advanced oxidation processes (SR-AOPs) is of great importance. This study presents Fe 3 O 4 -wrapped SBA-15 mesoporous silica catalyst (Fe 3 O 4 @SBA-15) for persulfate (PS) activation. The Fe 3 O 4 @SBA-15 with an Fe 3 O 4 to SBA-15 weight ratio of 3:1 exhibited an impressive carbamazepine (CBZ) removal efficiency of ~100% after 30 min of SR-AOP at an initial pH of 3.0, a temperature of 25 °C, an initial PS concentration of 300 mg L −1 and a catalyst concentration of 0.50 g L −1 . The primary oxidizing species produced in the system were identified as SO 4 − and HO by electron paramagnetic resonance spectra and radical quenching experiments. Benefiting from the synergetic effects of improved Fe 3 O 4 dispersion and enhanced adsorption of CBZ and PS by SBA-15, the as-obtained heterogeneous Fe 3 O 4 @SBA-15 catalysts offer large numbers of active sites for free radical generation and high surface concentrations of CBZ and PS for SR-AOPs, as verified by physicochemical characterization and Langmuir−Hinshelwood model analysis. In addition, the activity of Fe 3 O 4 @SBA-15 was maintained throughout six successive cycling tests. Various inorganic anions, including Cl − , NO 3 − , HCO 3 − , and CO 3 2− , as well as organic material in natural water, exert a negative impact on the Fe 3 O 4 @SBA-15 catalyzed SR-AOPs and deserve special attention.