Nano-magnetite supported by biochar pyrolyzed at different temperatures as hydrogen peroxide activator: Synthesis mechanism and the effects on ethylbenzene removal
2020
Yan, Jingchun | Yang, Lei | Qian, Linbo | Han, Lu | Chen, Mengfang
Nano-magnetite supported by biochar (nFe₃O₄/BC) pyrolyzed at temperatures of 300 °C–600 °C was developed to activate hydrogen peroxide (H₂O₂) for the efficient degradation of ethylbenzene in aqueous solution. It was revealed that the degradation efficiency of ethylbenzene and TOC removal were 96.9% and 36.2% respectively after the reaction for 40 min in the presence of initial concentration of 0.1 mmol L⁻¹ ethylbenzene, 2.76 g L⁻¹ nFe₃O₄/BC₅₀₀ with the mass ratio of nFe₃O₄ to BC₅₀₀ of 4:1 and 2.0 mmol L⁻¹ H₂O₂ at pH 7.0. Based on electron paramagnetic resonance (EPR), quenching experiment and X-ray photoelectron spectroscopy (XPS) data, both OH and O₂⁻ radicals were generated in the nFe₃O₄/BC₅₀₀ activated H₂O₂ system, and the OH radicals were the predominant species for the degradation of ethylbenzene. Through electron transfer process, mechanisms of Fe(II), phenolic hydroxyl group and persistent free radicals (PFRs) on BC surfaces accounted for the generation of OH radicals, and Fe(III) in nFe₃O₄ and formed from Fe(II) oxidation responsible for the generation of O₂⁻ radicals in the nFe₃O₄/BC activated H₂O₂ system were proposed.
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