Heterogeneous activation of persulfate for Rhodamine B degradation with 3D flower sphere-like BiOI/Fe3O4 microspheres under visible light irradiation

This study represents the first investigation on the application of persulfate (PS)/vis-light for the degradation of Rhodamine B (RhB) using bismuth oxyiodide magnetic composites (BiOI/Fe 3 O 4 , BOMCs). The 3D flower sphere-like BOMCs were successfully fabricated via a hydrothermal method, proving to be an excellent photocatalyst under visible light when evaluated by various characterization methods. The results demonstrated that BOMCs had a high photodegradation efficiency at pH 3.0–9.0 and the BiOI/Fe 3 O 4 (5:1) composite displayed the optimal catalytic performance. Inorganic ions such as Cl − showed promotion at a lower concentration, while significant inhibition was observed for higher concentrations of Cl − and HCO − 3 in the Vis/BOMCs/PS process due to the quenching effect. Moreover, 44.9% mineralization efficiency for total organic carbon and the excellent stability of BOMCs were demonstrated with limited iron leaching. Based on the scavenger experiments, the photocatalytic mechanism in the coupled system determined· SO − 4 and OH as the main reactive species. Eventually, the major intermediates are detected by GC/MS, and a possible photocatalytic degradation pathway of RhB is proposed in the Vis/BOMCs/PS process.