New magnetic nanobiocomposite CoFe₂O₄@methycellulose: facile synthesis, characterization, and photocatalytic degradation of metronidazole

In this work nanoCoFe₂O₄@methycellulose (MC) as a highly potent, magnetically separable photocatalyst by a facile, fast, and new microwave-assisted method with iron and cobalt salts on methyl cellulose in alkali medium was prepared. The nanobiomagnetic catalyst CoFe₂O₄@MC was characterized by field emission scanning electron microscope-energy dispersive spectroscopy (FESEM-EDS), mapping, the Brunauer–Emmett–Teller (S_BET), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), thermal gravimetric analysis, derivative thermogravimetric analysis, differential thermal analysis, vibrating sample magnetometer (VSM), and UV–Vis diffuse reflectance spectra. Powder XRD, and EDS analysis confirmed the formation of pure-phase spinel ferrites. FESEM analysis confirmed the sphere-like particle morphology of the samples with a smaller agglomeration. VSM analysis clearly showed the ferromagnetic nature of the nanoCoFe₂O₄@MC. The Ms value was 40.05 emu/g for simple separation by external magnetic fields. After characterization of this photocatalyst which showed its promising magnetic properties, the effective parameters of reaction time, initial antibiotic concentration, pH, photocatalyst loading, degradation kinetic, and removal efficiency of MNZ were investigated. The highest removal efficiency of 85.3% was observed in optimal conditions. The kinetic linear models showed that the nanoCoFe₂O₄@MC-catalyzed removal of MNZ follows either a pseudo-first order kinetic or the Langmuir–Hinshelwood equation. The new photocatalyst nanoCoFe₂O₄@MC was easily separated by a magnet and recycled without significant loss of photocatalytic activity after being used in four runs. This photocatalytic process is an excellent practical alternative for the removal of MNZ and similar antibiotic pollutants from various wastewaters.