Preparation and Efficient Tetracycline Removal of Co-Fe Bimetallic Carbon Nanotubes Catalytic Membranes

Carbon nanotube catalysts encapsulating cobalt-iron (CoFe) alloy nanoparticles (CoFe@Cs) were synthesized by calcination of cobalt-iron bimetallic Prussian Blue analogs (CoFe PBA), and further assembled on polyethersulfone (PES) membrane support by vacuum filtration to prepare composite catalytic membranes for catalytic activation of peroxymonosulfate and efficient degradation of tetracycline (TC). The morphology and structure of the samples were analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composition was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Based on the morphology, composition and performance, carbon nanotube catalysts (CoFe@Cs-900) were selected from the prepared series of CoFe@Cs, and further the reactive oxygen species (ROS) in the catalytic process was analyzed by reactive oxygen quenching experiments and electron paramagnetic resonance (EPR). The stability of the carbon nanotube catalytic membrane under long-term operation was tested under optimized conditions. The results showed that the calcination temperature played an important role in regulating the morphology and composition of the catalysts. Among them, the carbon nanotube catalyst prepared by calcination at 900 ℃ can produce the reactive oxygen species, including sulfate radicals (·SO₄⁻) and singlet oxygen (¹O₂), for the rapid removal of tetracycline. The carbon nanotube catalytic membrane achieved more than 99% removal of TC in continuous 24 h cross-flow filtration, and the water flux was maintained at 172 L/(m²·h). Overall, the catalytic membrane showed excellent degradation performances and potential application.