For traditional Fenton processes, the quenching behavior of radical contenders (e.g., most aliphatic hydrocarbons) on hydroxyl radicals (·OH) usually hinders the removal of target refractory pollutants (aromatic/heterocyclic hydrocarbons) in chemical industrial wastewater, leading to excess energy consumption. Herein, we proposed an electrocatalytic-assisted chelation-Fenton (EACF) process, with no extra-chelator addition, to significantly enhance target refractory pollutant (pyrazole as a representative) removal under high ·OH contender (glyoxal) levels. Experiments and theoretical calculations proved that superoxide radical (·O2-) and anodic direct electron transfer (DET) effectively converted the strong ·OH-quenching substance (glyoxal) to a weak radical competitor (oxalate) during the electrocatalytic oxidation process, promoting Fe2+ chelation and therefore increasing radical utilization for pyrazole degradation (reached maximum of ∼43-fold value upon traditional Fenton), which appeared more obviously in neutral/alkaline Fenton conditions. For actual pharmaceutical tailwater treatment, the EACF achieved 2-folds higher oriented-oxidation capability and ∼78% lower operation cost per pyrazole removal than the traditional Fenton process, demonstrating promising potential for future practical applications.
Keywords: Electrocatalytic-assisted chelation-Fenton; Fenton oxidation; In situ pollutant utilization; Multipollutant mixed matrix; Radical utilization.
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