[Degradation 2,2',4,4'-Tetrabromodiphenyl Ether by Activated Peroxymonosulfate Using Magnetic Biochar Supported...

Polybrominated diphenyl ethers(PBDEs) are potentially harmful to human health and the ecological environment. It is, therefore, of great significance to develop efficient, economic, and environmentally-friendly advanced oxidation systems for their effective degradation. Here, a magnetic biochar supported manganese dioxide composite(α-MnO₂/MWB) synthesized by hydrothermal methods was used as a catalyst to activate peroxymonosulfate(PMS) in the degradation of 2, 2', 4, 4'-tetrabrominated diphenyl ether(BDE-47). The prepared materials were characterized by SEM, XRD, FT-IR, and BET. The results showed that α-MnO₂/MWB had the best catalytic performance, and the highest degradation efficiency reached 94% under optimal conditions(α-MnO₂/MWB mass ratio=1:2, catalyst dosage=0.05 g·L^-1, PMS concentration=5 mmol·L^-1, BDE-47 concentration=1 mg·L^-1). The effect of initial pH on the system was not distinct, while chloride ions(Cl^-) and humic acid(HA) inhibited the degradation of BDE-47. In comparison, nitrate ions(NO₃^-) and bicarbonate ions(HCO₃^-) had no notable effect on the degradation. SO₄^-· and·OH were the key free radicals in the degradation of BDE-47 in this system, with SO₄^-· being dominant. As showed by the XPS characterization of the materials before and after the reaction, a change in the valence states of Mn and Fe was the main reason for the activation of PMS. It was also revealed that α-MnO₂/MWB composites maintained high catalytic performance after being reused up to four times.