Degradation of phenol and sulfamethoxazole with persulfate and ozone with nano‐MnO₂–biochar composites

BACKGROUND

In this study, nano‐MnO₂–biochar composites were synthesized as catalysts to promote the oxidation of recalcitrant organic contaminants. The MnO₂ nanoparticles coated on biochar were hypothesized to enhance the oxidation of phenol and sulfamethoxazole (SMX) using ozone and/or persulfate.

RESULTS

The optimal percentage of MnO₂ coating on the surface of biochar was determined, and the synthesis of nano‐MnO₂‐coated biochar was confirmed via scanning electron microscopy–energy dispersive X‐ray spectroscopy (EDS), X‐ray diffraction, and EDS line mapping analyses. Compared with oxidation using ozone or persulfate in the presence of either nano‐MnO₂ or biochar, the synthesized nano‐MnO₂–biochar composite markedly enhanced the oxidation of phenol and SMX. This was probably due to the spreading of MnO₂ nanorods on the surface of biochar and the synergistic involvement of nano‐MnO₂ and biochar as catalysts. X‐ray photoelectron spectroscopy analysis confirmed the involvement of Mn³⁺ in MnO₂ to promote oxidation using ozone or persulfate. The co‐existence of ozone and persulfate could also promote oxidation. Hydroxyl radicals (OH⋅) and persulfate radicals (SO₄⁻⋅) were major reactive oxygen species for ozone and persulfate systems, respectively.

CONCLUSION

Results suggest that the synthesized nano‐MnO₂–biochar composites may be effective catalysts for various types of advanced oxidation processes in environmental remediation.

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