The decomplexation of Cu-EDTA by electro-assisted heterogeneous activation of persulfate via acceleration of Fe(II)/Fe(III) redox cycle on Fe-MOF catalyst

• A novel Fe-MOF heterogeneous catalyst is prepared by microwave method. • Electro-Fe-MOF activated persulfate is firstly degrade Cu-EDTA with high RSE. • The redox cycle of Fe(II)/Fe(III) was accelerated with electric-assisted. • Deposited Cu species on Fe-MOF enhance the performance of heterogeneous catalyst. • Various metal-EDTA complexes were efficiently degraded by EC/Fe-MOF/PS system. As a metal complex widely used in the electroplating industry, the degradation of Cu-EDTA in the wastewater treatment process is difficult for its strong stability, it is a crucial but extremely challenging task. In this study, a novel Ferreous metal–organic frameworks (Fe-MOF) heterogeneous catalyst was synthesized by a convenient and fast microwave method. Combined with electrochemical (EC) method and persulfate (PS), an EC/Fe-MOF/PS system was firstly applied to degrade the Cu-EDTA that was completely removed under the optimized conditions. During this process, the redox cycle was accelerated with electrical assistance and the ratio of Fe(II)/Fe(III) on the Fe-MOF was significantly increased, which improved the catalytic ability. Additionally, the degradation performance was obviously enhanced with the increased cycles. The phenomenon occurred because that Cu species derived from the decomposition of Cu-EDTA was deposited on Fe-MOF surface, and the additional catalytic ability was obtained from the Cu(0)/Cu(I)/Cu(II). The detailed pathway of Cu-EDTA degradation was proposed based on the intermediates identified by FT-ICR-MS and the mechanism was also investigated by Electron spin resonance (ESR) and quenching experiments of Reactive oxygen species (ROS). Furthermore, the EC/Fe-MOF/PS system could also represent excellent performance for the degradation of various metal-EDTA complexes. This study provided an efficient and sustainable approach for the degradation of refractory organic pollutants.