Fabrication of Bi1.81MnNbO6.72/sulfite system for efficient degradation of chlortetracycline

The design of eco-friendly Bi 1.81 MnNbO 6.72 /sulfite system for efficient degradation of chlortetracycline was achieved. The feasibility of synthesizing Bi 1.81 MnNbO 6.72 by hydrothermal method was determined by X-ray diffraction. The magnetic test suggested that Bi 1.81 MnNbO 6.72 possessed paramagnetic properties, indicating unpaired electrons were present. Scanning electron microscope and transmission electron microscopy images revealed that Bi 1.81 MnNbO 6.72 octahedra exhibited exposed [1,1,1] crystal plane containing high density of Bi, Mn and Nb metal atoms. Large numbers of metal atoms will facilitate heterogeneous catalytic process. In a batch system with aeration, Bi 1.81 MnNbO 6.72 could be used as sulfite activator for the disposal of chlortetracycline. The reaction kinetics of the degradation process conformed to the pseudo-second-order kinetic model. In Bi 1.81 MnNbO 6.72 /sulfite process, initial pH, Bi 1.81 MnNbO 6.72 dosage, sulfite and chlortetracycline concentrations, as well as inorganic salt ions had great effect on chlortetracycline degradation. Under optimal conditions, the efficiency of Bi 1.81 MnNbO 6.72 /sulfite system for degradation of chlortetracycline could reach 76.2%. Moreover, Mn (II) plays a key role in the initiation of the catalytic reaction in Bi 1.81 MnNbO 6.72 /sulfite process. Generated SO 3 ●‒ could act as main reactive species in Bi 1.81 MnNbO 6.72 /sulfite process, while HO ● was also involved. Three new degradation products were detected by UHPLC/MS/MS and the possible degradation pathways in this system were proposed. Based on this, we believe that Bi 1.81 MnNbO 6.72 /sulfite is a type of process for degradation of organic contaminants with research significance and application prospects.