Coupled effects of Fenton-like systems with different concentrations of H 2 O 2 /Biochar on diethyl phthalate removal: Dominant role of environmental persistent free radicals (EPFRs).

To investigate the impact of different H ₂ O ₂ concentrations on the Fenton-like systems of H ₂ O ₂ /biochar, this study examined the mechanism of the physical structure and environmental persistent free radicals (EPFRs) of biochar during diethyl phthalate (DEP) removal by the Fenton-like system. The peak-splitting method was utilized to differentiate EPFRs types in cotton stalk biochar produced at different temperatures. High-temperature environments promote π-electron delocalization, which facilitates phenyl π free radicals and σ-π oxygen-containing free radicals. By analyzing relationships between the removal rate K ₁ and removal constant K _obs of DEP with the structural properties of biochar, it was discovered that EPFRs concentrations in biochar had a significant positive correlation with K ₁ (r = 0.92) and K _obs (r = 0.97). Different H ₂ O ₂ concentrations added to the biochar removal system resulted in varied DEP removal efficiency. Among them, CS ₅₀₀ , CS ₅₅₀ , and CS ₆₀₀ exhibited superior DEP removal efficiency when H ₂ O ₂ concentration was 5 mM.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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