One-step Fabrication of Graphitic C3N4/Fe0 Composite from Plastic and Bauxite Residue for Catalytic Removal of Enrofloxacin

The presence of antibiotics in wastewater poses significant risks to ecosystem due to their persistence and role in fostering the development of antibiotic-resistant strains of bacteria. This study explores the thermochemical conversion of waste materials (nylon and red mud) into a carbon composite and evaluates its efficacy as a catalyst for advanced oxidation process to remove enrofloxacin in aqueous phase. The composite was produced by co-pyrolyzing nylon and red mud under an inert condition. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the composite consisted of graphitic C3N4 coated on red mud particles rich in Fe0 content (g-C3N4/Fe0). The thermogravimetric/gas analysis indicated that red mud enhanced the thermolytic kinetics of nylon, leading to an increase of syngas production. The resulting composite effectively catalyzed persulfate activation to drive enrofloxacin oxidation. Notably, the composite fabricated at 900 ˚C was more efficient in oxidizing enrofloxacin than other composites produced at 400 and 600 ˚C because of its high Fe0 content and the presence of pyridinic N. The composite also exhibited good reusability to sustain > 60% enrofloxacin removal even after 9 reaction cycles. This study proposes an eco-friendly waste valorization strategy to produce an environmental medium through a one-step process.