Tannin-functionalized Mn3O4 as support for FeNiB alloy to construct sono-Fenton-like reaction for the degradation of antibiotic pollutants in water

In this paper, iron-based amorphous alloy (FeNiB) supported on Tannin-functionalized Mn3O4(Mn3O4-TA@FeNiB) were prepared and used as a heterogeneous catalyst to degrade ciprofloxacin (CIP) and norfloxacin (NOR) in aqueous solution by the ultrasound (US)-assisted Fenton-like process. The physicochemical properties of the resulting Mn3O4-TA@FeNiB were characterized by SEM, TEM, XRD, BET, FTIR, XPS and other techniques. The results showed that 92.04% and 90.34% of CIP and NOR at their initial concentration of 10 mg L−1 were removed by the sono-Fenton-like system after 60 min in comparison with 85.24% and 82.52% of CIP and NOR removal after 300 min by Mn3O4-TA@FeNiB alone and the rate constants of the former were 6.65 and 6.80 times higher than those of the latter, respectively. Excellent catalytic performances were benefited from synergistic interactions between US, H2O2 and Mn3O4-TA@FeNiB. Mn3O4-TA as a support and stabilizer could effectively load and disperse FeNiB, meanwhile providing reactive area and active sites (Mn2+/Mn3+). FeNiB was corroded to produce Fe2+ and Ni2+, thus forming reversible redox reactions between polyvalent metals, which ensured Fenton-like reaction to be effectively proceeded. While US accelerated the oxidation process to generate more reactive species, which resulted in higher catalytic efficiencies and reaction rates of CIP and NOR degradation. Metal leaching and cycling experiments showed that Mn3O4-TA@FeNiB exhibited good stability and reusability. Finally, the degradation intermediates of CIP were analyzed and the possible degradation mechanisms and pathways were proposed. These results indicated that Mn3O4-TA@FeNiB had great potential as an effective and low-cost catalyst in US-assisted Fenton-like process for removal of the emerging pollutants.