Promoting Co(II)-EDTA decomplexation by central atom oxidation in contact-electro-catalysis

Low-level radioactive wastewater containing Co(II)-EDTA generated in the nuclear industry is harmful to the environment, but it is difficult to remove owing to the high stability of metal-organic complexes. Here, we report efficient contact-electro-catalysis (CEC) to achieve the decomplexation of Co(II)-EDTA by using commercial fluorinated ethylene propylene (FEP) powder as a dielectric catalyst. The reaction generated reactive oxygen species through solid-liquid interfacial charge transfer, disrupting the chemical bonds and then oxidizing the central atoms in Co(II)-EDTA to form Co(III)-EDTA with vacancies. The Co(III)-EDTA could be easily removed from the solution under alkaline conditions. The decomplexation efficiency reached a high value of 41.6%, with a constant reaction rate of 0.024 min^-1 in 240 minutes. The FEP also exhibited excellent recyclability over 40 h without obvious changes. Unlike conventional advanced oxidation processes, this approach does not require the use of electrodes or chemical oxidants, leading to low energy consumption. This approach also holds great potential for green wastewater management via integration with ambient mechanical energy sources (e.g., wind and hydrostatic pressure).