An extra-chelator-free fenton process assisted by electrocatalytic-induced in-situ pollutant carboxylation for target refractory organic efficient treatment in chemical-industrial wastewater

For traditional Fenton processes, the quenching behavior of radical contenders (e.g., most aliphatic hydrocarbons) on hydroxyl radicals (center dot 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 center dot OH contender (glyoxal) levels. Experiments and theoretical calculations proved that superoxide radical (center dot O-2(-)) and anodic direct electron transfer (DET) effectively converted the strong center dot 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 similar to 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 similar to 78% lower operation cost per pyrazole removal than the traditional Fenton process, demonstrating promising potential for future practical applications.

Automated summary

The quenching effect of radical contenders hinder the removal of target refractory pollutants in traditional Fenton processes. To overcome this, an electrocatalytic-assisted chelation-Fenton (EACF) process was proposed, which significantly enhanced the removal of target refractory pollutant (represented by pyrazole) under high contender levels. The EACF achieved higher oxidation capability and lower operation cost compared to traditional Fenton process in the treatment of pharmaceutical tailwater.