Photocatalytic treatment for antibacterials wastewater with high-concentration using ZnFe2O4/Bi7O9I3 magnetic composite with optimized morphology and structure

Emerging antibacterials contaminations in aquatic environment have posed acute and chronic toxicities to human health and increasingly disturbance to ecosystem and environment. One of the main sources of antibacterials residues is the pharmaceutical wastewater containing antibacterials with high concentration (100–500 mg L−1). In comparison with most photocatalysts competent for removing antibacterials with low-concentration (10–50 mg L−1), ZnFe2O4/Bi7O9I3 composites in our research have been utilized to effectively treat antibacterial wastewater with high concentration (100, 400 mg L−1). XRD, TEM, HRTEM, EDS and XPS measurements were carried out to characterize the composition and microstructure of the composites. The roles of optimized morphology and adjusted structure in improving the photocatalytic activity are researched. The bi-functional effects of combination ZnFe2O4 with Bi7O9I3 on the enhanced photocatalytic activity and magnetic property are clarified. Superior removal efficiencies of 30% ZnFe2O4/Bi7O9I3 composite for LVFX (100 mg L−1), SD-Na (100 mg L−1) and TC (400 mg L−1) were respectively determined as 95.1% in 100 min, 94.6% in 4 h and 96.3% in 30 min, which indicates an efficient approach for pharmaceutical wastewater. The magnetic separation capacity and recycling performance after four runs are assessed. Mechanism of the enhanced photocatalytic performance of 30% ZnFe2O4/Bi7O9I3 is discussed based on its reticular-surround microstructure, optimized morphologies of ZnFe2O4 and Bi7O9I3 in the composite and the beneficial staggered-type band structure. Our research provides a novel and significant technique to treat real pharmaceutical wastewater containing high-concentration antibacterials.