Fabrication of sandwich-like super-hydrophobic cathode for the electro-Fenton degradation of cefepime: H2O2 electro-generation, degradation performance, pathway and biodegradability improvement

Abstract Several composite cathodes were prepared using graphite, carbon nanotube (CNT) and PTFE, and their elemental composition, surface morphology, physical and electrochemical properties were studied by various characterization techniques. It was found that the hydrophobic property of the prepared cathodes could be greatly enhanced by changing their surface morphologies using polyurethane sponge in cathode-shaping, which successfully allowed the preparation of super-hydrophobic carbon cathode, resulting in the enhanced reduction of O2 to H2O2. Based on the above finding, a sandwich-like super-hydrophobic carbon cathode was fabricated and used in the electro-Fenton process for the degradation of cefepime. The recommended cathode exhibited an ideal performance for H2O2 electro-generation and a favorable stability. The cathode submerged in air-aeration solution (pH 3.0) has produced 376 mg L−1 H2O2 with an observed current efficiency (CE) of 40 % via the electrolysis of 60 min at the optimum potential. The developed electro-Fenton process presented the degradation efficiency of nearly 100 % within 10 min for 60 mg L−1 cefepime, in which the degradation of cefepime mainly depended on the generation of hydroxyl radicals (∙OH). The organic intermediates formed during cefepime degradation were identified and the degradation pathway was proposed. More over, the electro-Fenton degradation of cefepime evidently reduced the solution toxicity and improved the biodegradability, suggesting the electro-Fenton oxidation may be adopted as a pretreatment alternative prior to the biological treatment of cefepime-containing wastewater.