Enhanced degradation of amiloride over Bi2FeNbO7/bisulfite process: Key factors and mechanism

Abstract

Construction of Bi2FeNbO7/bisulfite system for abatement of pharmaceutical residue was achieved. An attempt to synthesize Bi2FeNbO7 through hydrothermal technique was confirmed by X-ray diffraction. The magnetic field experiment revealed that Bi2FeNbO7 possessed a saturation magnetization of 6.99 emu/g, indicating magnetic attributes of Bi2FeNbO7. Scanning electron microscopy images showed that Bi2FeNbO7 exhibited regular octahedra in the size of 200–300 nm. In a self-made device, the activation of sodium bisulfite using Bi2FeNbO7 for the disposal of amiloride has been carefully explored. The effects of solution pH, sodium bisulfite concentration, Bi2FeNbO7 dosage, amiloride concentration, coexisting ions, and water matrix on the performance of Bi2FeNbO7/bisulfite system was investigated. The catalytic performance of Bi2FeNbO7/bisulfite to degrade amiloride was considerably higher than that of traditional iron oxides. The maximum removal efficiency of amiloride was 97.9% in Bi2FeNbO7/bisulfite process. The involvement of Fe might be crucial for activating bisulfite to create active species. The dominating radical in Bi2FeNbO7/bisulfite process was identified as SO3•‒. With the help of UHPLC/MS/MS, three new degradation products of amiloride were found. Dehalogenation and deamination of amiloride might account for the formation of these transformation products. This work provides a highly efficient Bi2FeNbO7/bisulfite process for the disposal of pharmaceutical pollutants in water treatment.