Heterogeneous activation of persulfate by Ag doped BiFeO3 composites for tetracycline degradation
2020
Ouyang, Mengyun | Li, Xiaoming | Xu, Qiuxiang | Tao, Ziletao | Yao, Fubing | Huang, Xiaoding | Wu, You | Wang, Dongbo | Yang, Qi | Chen, Zhuo | Pi, Zhoujie
Persulfate (PS) activation have been extensively considered as a promising technology for removing recalcitrant pollutants, due to their production of radicals with superior oxidation reactivity. However, a catalyst with high reactive and convenient recovery for PS activation still remains to be developed. In this work, the silver-doped bismuth ferrite (Agₓ-BiFeO₃, x = 0.1, 0.2, 0.3 and 0.4) catalysts with variable Ag content were synthesized via a facile sol-gel method and applied as heterogeneous catalyst in PS activation for tetracycline (TC) degradation. Ag₀.₄-BiFeO₃ presented the best catalytic activity compared with other Ag doped BiFeO₃ composites, 91% TC could be efficiently removed within 60 min under optimized conditions and the reaction rate constant was 0.0338 min⁻¹. On the basis of the characterization analysis and catalytic test results, Ag could be the effective active site in PS activation and had a significant effect on PS activation. Moreover, the initial pH has negligible effect on the catalytic performance, indicating that Ag₀.₄-BiFeO₃/PS system could work in a wide pH range. The results of electron spin-resonance spectroscopy and radical quenching tests suggested that both SO₄⁻ and OH radicals were involved in the Ag₀.₄-BiFeO₃/PS system. The possible mechanism of Ag₀.₄-BiFeO₃ activating PS and the major degradation pathway of TC degradation were proposed. At last, the reusability experiment results proved that Ag₀.₄-BiFeO₃ catalyst still has a high catalytic performance after 4 times used.
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