Reductive degradation of tetrabromobisphenol A over iron-silver bimetallic nanoparticles under ultrasound radiation

The present study described the degradation behavior of tetrabromobisphenol A (TBBPA) in Fe-Ag suspension solutions under ultrasonic radiation (US). The Fe-Ag bimetallic nanoparticles with core-shell structure were successfully synthesized by reduction and deposition of Ag on nanoscale Fe surface, and were further characterized by BET, XRD, TEM, SEM, X-ray fluorescence and X-ray photo-electron spectroscopy. The results revealed that the displacement plating produced a non-uniform overlayer of Ag additive on iron; the as-synthesized bimetallic nanoparticles were spherical with diameters of 20-100 nm aggregated in the form of chains. Batch studies demonstrated that the TBBPA (2 mg L−1) was completely degraded in 20 min over Fe-Ag nanoparticles, which has higher degradation efficiency than Fe0 nanoparticles under US. The effects of Fe-Ag bimetallic nanoparticles loading, initial TBBPA concentration, pH of the solution, Ag loading and temperature on the reduction efficiency of TBBPA under US were investigated. The complete reduction of TBBPA in 20 min was determined selectively under the conditions of pH (pH = 6.0 ± 0.5), Ag loading (1 wt.%) at 30 °C over the fabricated Fe-Ag nanoparticles. Additionally, the major intermediates identified by LC-MS technique were tri-BBPA, di-BBPA, mono-BBPA and BPA and the degradation mechanism was also proposed.