Highly remediation capacity of tetracycline by iron‑manganese bimetallic materials: Performance and mechanisms

To enhance the decontamination capacity of zero-valent iron and mitigate its susceptibility to oxidation and passivation, manganese (Mn) was introduced in the current study to prepare the iron‑manganese bimetallic material by one-step chemical reduction method to remove tetracycline (TC). A series of methods including Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), Transmission Electron Microscope (TEM), Vibrating Sample Magnetometer (VSM) and X-ray Photoelectron Spectroscopy (XPS) were applied to investigate the characteristics of the nanocomposite. Furthermore, batch experiments were conducted to explore the effects of key parameters such as dosage, pH, initial concentration and coexisting ions on the removing TC with Fe-Mn bimetal nanocomposite. At the same time, reaction mechanism and degradation pathways were examined. The results showed that the bimetallic particles were highly paramagnetic for recover and evenly distributed, consisting of zero-valent Fe and Mn as well as their respective oxides. The removal kinetics of TC showed a fast process and reached a removal capacity of 330.17 mg/g within a reaction time of 60 min under TC concentration of 100 mg/L, pH = 3 and dosage of 0.3 g/L. The coexistence of both cations and anions had significant effect on the TC removal in the experimental conditions. Finally, OH and O2− played a major role in the redox reaction and the possible reaction mechanism and degradation pathways were demonstrated. To sum up, the Fe-Mn bimetal nanocomposite was proved to be promising and effective for treating TC-containing wastewater. [Display omitted] •A nano-Fe/Mn bimetal material in zero-valent and oxides was successfully prepared.•The composite showed high remediation performance (330.17 mg/g) of tetracycline.•The OH and O2− were the dominant reactive species in the redox reaction.•The iron and manganese could mutually promote the degradation in different valence states.