Heterogeneous electro-Fenton system with Co/N-GO modified cathode to degrade phenolic organic pollutants: The main role of singlet oxygen

Heterogeneous electro-Fenton (hetero-EF) system has attracted much attention for the removal of refractory organic pollutants. In this study, hetero-EF for phenol degradation was constructed to use cobalt and nitrogen co -doped graphene (Co/N-GO) modified cathode. The microstructure and composition of the modified cathode material were explored using SEM, TEM, XPS, and XRD. Systematic investigation of the effects of various factors on phenol removal showed that the phenol removal rate could reach 97.00 % in the hetero-EF system by Co/N-GO within 4 h, and the substrate could be removed well in a wide pH range (3-9). The phenol removal rate was still up to 90.71 % after eight consecutive reaction cycles. Combined with the quenching test and EPR analysis, singlet oxygen (1O2) played a major role in the degradation of phenol. Further research revealed that & BULL;OH and & BULL;O2  were not only involved in oxidative degradation of pollutants, but also contributed to the production of 1O2. Meanwhile, dissolved oxygen (DO) also participated in the formation of 1O2. The study is beneficial to further develop the potential of hetero-EF system for environmental organic pollution remediation.