In this study, magnetic iron oxide nanoparticles (Fe3O4) were produced by a green method, using aqueous extract of spenttea waste as the reducing agent, which was subsequently used to prepare the magnetic and biodegradable Fe3O4/cellulose nanocomposite. The nanostructures were compared using advanced techniques such as UV–Vis spectrophotometry, Fourier transform infrared, X-ray spectroscopy, imaging by electron microscopy, thermal analysis, and vibrating-sample magnetometery. The data from the analyses showed that the synthesized nanocomposite had a spherical shape with an average particle size of 15.5 nm, which is smaller than the mean (28 nm) of the pure Fe3O4 nanoparticles. These results also showed that the prepared nanocomposite had a higher thermal resistance (450–800 °C) compared to pure cellulose. Another important feature of the nanoscale was the magnetic property (25 emu/g), which was smaller than that obtained in pure Fe3O4 nanoparticles (45 emu/g). In addition, the swelling capacity was studied as one of the functional capabilities of the nanocomposite, which was 139.3 g/g, more than the swell capacity obtained for pure cellulose (66.8 g/g). According to the results, the prepared Fe3O4/cellulose nanocomposite is suggested to be applied in metronidazole drug delivery system regarding its suitable and acceptable properties, such as high absorption capacity, controlled magnetic transferability and biodegradability as well as non-toxicity.
