Nanoscale magnetite: New synthesis approach, structure and properties

Highlights: • Nanoscale magnetite (NM) Fe₃O₄ has been synthesized for the first time from a waste by means of the new SHTDH approach. • NM has been verified via FTIR, Raman, TEM, EDX and XRD. • NM was classified as nanoporous and superparamagnetic according to the results of N₂ adsorption–desorption and VSM. • NM is a promising candidate for different applications. Nanoscale magnetite (Fe₃O₄) (NM) is widely used for various industrial and biomedical applications. Nevertheless, the preparation of NM with desirable structure and properties by means of simple, rapid, and environmentally friendly synthesis remains a major challenge. In this study, NM was synthesized for the first time from a waste material, namely, water deironing sludge, using a novel "sharp high-temperature dehydration" (SHTDH) approach. The magnetite obtained was verified via Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). XRD results revealed that the as-synthesized NM crystallites were 7 nm in size. The TEM images showed a hierarchical nanostructure characterized by primary nanoparticles (with an average size of 4.5 nm) and their secondary arrays (mean size 57 nm). The N₂ adsorption–desorption measurements have enabled classify the NM material as nanoporous. According to the magnetic measurements, the synthesized NM exhibited superparamagnetic behavior. The findings suggest that the SHTDH is a facile, time-effective, and environmentally friendly approach for the synthesis of nanoparticles with ultrasmall sizes. Furthermore, it can provide a new pathway for the preparation of novel materials for various industrial and biomedical applications.