Synergistic Effect of Cathode/peroxymonosulfate/Fe3+ on Phenol Degradation

- Cathode/PMS/Fe3+ and EC/PMS/Fe3+ systems have similar effect on COD removal.
- Cathode/PMS/Fe3+ system is more effective on Fe3+/Fe2+ conversion.
- Cathodic regeneration of Fe2+ is improved by current density, PMS and Fe3+ dosage.
- SO4− is the predominant radical species in Cathode/PMS/Fe3+ system.

A novel Cathode/peroxymonosulfate(PMS)/Fe3+ system is developed and its performance is evaluated by phenol degradation. The factors affecting phenol degradation such as current density, PMS dosage, Fe3+ dosage, electrolyte concentration and initial phenol concentration were investigated. Compared with the non-separated system (EC/PMS/Fe3+), the separated Cathode/PMS/Fe3+ system can prevent the current loss due to anodic oxidation of Fe2+. A synergistic effect is observed in Cathode/PMS/Fe3+ system due to the cathodic regeneration of Fe2+ from Fe3+. The regeneration of Fe2+ on cathode surface can be improved by increasing of current density, PMS dosage, Fe3+ dosage and initial phenol concentration, and results in an improvement on the organics removal, while PMS consumption rate mainly depends on current density in the Cathode/PMS/Fe3+ system. Increasing of SO42− concentration has a negative effect on phenol degradation since the reactivity of SO4
- − is depressed. Both SO4− and OH exist and play roles in the Cathode/PMS/Fe3+ system, while SO4− is found to be the predominant radical species.

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