A bimetallic (Co/Fe) modified nickel foam (NF) anode as the peroxymonosulfate (PMS) activator: Characteristics and mechanism

A bimetallic (Co/Fe) modified nickel foam (NF) anode was fabricated as an effectively electrochemical peroxymonosulfate (PMS) activator for the removal of tetracycline (TC). The results showed that the bimetallic modification through solvothermal treatment could result in a significant increase of electrochemical properties, which were further enhanced by the subsequent calcination treatment at 400 ℃. The fabricated c-CoFe-NF anode showed high catalytic performance as the PMS activator and the TC removal efficiency could reach 93.05 % within 1 h. The activation energy (21.23 kJ/mol) during PMS activation by c-CoFe-NF anode was about 2.58 times lower than that of bare NF anode (54.79 kJ/mol), and the corresponding reaction rate was enhanced by 2.68 times. The quenching experiments and the electron paramagnetic resonance (EPR) tests showed that the generated reactive oxygen species (including O2- and 1O2) and SO4- played important roles in TC removal. 1O2 was mainly originated from the dismutation of O2-, while the O2- was generated via hydrolysis of SO4- and the electrochemical oxygen reduction reaction (ORR). Furthermore, EPR investigation results also demonstrated that the SO4- formed during the anodic PMS activation became the main contributor for the generation of the reactive oxygen species. The current investigation gave a comprehensive and new insight into the roles and characteristics of the transformation among different reactive radicals generated during the anodic PMS activation process. Furthermore, the fabricated c-CoFe-NF anode provided an alternative for the degradation of pollutants applied in wastewater treatment based on the electrochemical advanced oxidation process (EAOP)