Facile Synthesis of Magnetic Znfe2o4/AC Composite to Activate Peroxydisulfate for Dye Degradation Under Visible Light Irradiation

Abstract A facile hydrothermal method was employed to synthesize magnetic ZnFe2O4/active carbon (AC) composite, which was firstly used to activate peroxydisulfate (PDS) for rhodamine B (RhB) degradation under visible LED light irradiation. The ZnFe2O4/AC(4/1)/PDS system can enhance the RhB degradation efficiency by 32.1% compared with ZnFe2O4/PDS system due to the synergistic effect between ZnFe2O4 and AC. The influence of operational parameters (catalyst dosage, PDS concentration, temperature, solution pH and coexisting inorganic anions) on RhB degradation was studied, and the complete degradation of RhB was achieved after 80 min of reaction at operational condition: 0.3 g/L of ZnFe2O4/AC(4/1) and 1.5 g/L of PDS, solution pH of 2.74, reaction temperature of 25°C and initial RhB concentration of 20 mg/L. The quenching experiments, EPR test and XPS analysis were employed to reveal the proposed mechanism, which demonstrated that 1O2 played a more important role than other reactive species (SO4•‒, •OH, O2•−, and h+) in the degradation of RhB. The generation of 1O2 via the two routes was as follows: (i) the in-situ formed active oxygen (O*) reacted with HSO5− to produce 1O2; (ii) O2•− was oxidized by h+ to form 1O2. After five consecutive cycles, the photo-degradation efficiency of RhB by ZnFe2O4/AC(4/1) catalyst slightly decreased from 84.6–79.6%, indicating the excellent reusability of ZnFe2O4/AC(4/1) in oxidation system. Under visible LED light irradiation, the performance of ZnFe2O4/AC/PDS oxidation system for the removal of RhB from the different real water matrices was also studied.