Electro-Fenton degradation of ciprofloxacin with highly ordered mesoporous MnCo2O4-CF cathode: Enhanced redox capacity and accelerated electron transfer.

Highlights • MnCo 2 O 4 nanoparticles were used for the first time in electro-Fenton process. • High ciprofloxacin removal with MnCo 2 O 4 modified cathode was obtained. • Co atom was more electron-rich than Mn atom in MnCo 2 O 4. • Electron transfer rate on the surface of MnCo 2 O 4 was enhanced. • Excellent catalysis of MnCo 2 O 4 with good stability and low metal leaching. Abstract The emergence of antibiotics in the environment, especially in drinking water, poses potential harm to human health. It's urgent to develop effective methods to remove antibiotics in drinking water. In this work, a series of mesoporous Mn x Co 3−x O 4 nanoparticles with high surface area were successfully synthesized and firstly used as effective stable electro-Fenton catalysts to degrade ciprofloxacin (CIP). The removal of CIP achieved to 100% within 5 h. Experimental and density functional theory (DFT) studies verified the existence of redox pairs of Mn2+/Mn3+ and Co2+/Co3+. Scanning electrochemical microscopy (SECM) results suggested that the redox reaction capacity of MnCo 2 O 4 was enhanced and the electron transfer rate on the surface of this bimetallic oxide was 2.67 and 1.6 times the number of MnO 2 and Co 3 O 4 , respectively. The effective degradation of CIP was mainly associated with the increased electron transfer rate and advanced redox reactivity owing to the synergistic effect of manganese and cobalt entrapped in the matrix of mesoporous structure which provided more accessible active sites. The degradation intermediates and possible process mechanism were investigated in detail. The reusability of MnCo 2 O 4 -CF cathode was evaluated five cycles with minimal ion leaching which the concentration of Mn and Co in the system was lower than 2.5 and 3.4 ppm, respectively. This work provides further understanding for removal process of organic pollutants by investigation of redox couple and electron transfer rate of the promising MnCo 2 O 4 -CF cathode. [ABSTRACT FROM AUTHOR]