The strategy to promote the degradation of phenol by electro-Fenton: The synergistic effect of N-doping and electrode aeration promotes the adsorption capacity of activated carbon cathode and Fe2+/Fe3+ cycle

The efficient cycle of Fe2+/Fe3+ is an important factor for the effective generation of ·OH in the electro-Fenton system. The mismatch between pollutant concentration and ·OH concentration is the key reason for the low utilization rate of ·OH in the electro-Fenton system. Improving the simultaneous adsorption capacity of cathode for Fe3+ and phenol is the key to improve the generation rate and utilization rate of ·OH. However, there is a competitive adsorption between Fe3+ and phenol. Therefore, the effects of N-doping and electrode aeration (EA) on the adsorption performance of activated carbon cathode, Fe2+/Fe3+ cycle and phenol degradation in electro-Fenton system were studied by experiments and characterization. The results showed that the adsorption capacity of NGAC-EA for Fe3+ and phenol increased by 27.57 % and 31.82 %, respectively. N-doping and EA significantly promoted the Fe2+/Fe3+ cycle. The electro-Fenton system of NGAC-EA group could quickly remove 40.445 mg/L phenol within 180 min, which was 1.42 times that of GAC-SA (28.5 mg/L). N-doping can provide suitable pore structure and a large number of adsorption sites for activated carbon, and promote the transfer of electrons in the external circuit. EA can improve the mass transfer of the solution. The synergistic effect of N-doping and EA can maximize the degradation effect of the electro-Fenton system. This study provides a new direction and theoretical guidance for the development of electro-Fenton technology, which can encourage the academic community to devote themselves to operable and practical academic research.