Effects of precursor concentration on the properties of magnetic iron oxide nanoparticles synthesized using brown seaweed (Sargassum crassifolium) extract

Abstract This work reports the influence of precursor concentration on the thermal and optical properties of magnetic iron oxide nanoparticles (MIONPs) synthesized via the green synthesis route. A brown seaweed (Sargassum crassifolium) extract was used to mediate the reduction of iron precursors. Ultraviolet–visible spectra showed a sharp peak between 315 and 375 nm, which corresponds to the absorbance of MIONPs. This peak intensified with an increasing concentration of iron precursors. The Fourier transform infrared spectra revealed the presence of the transmittance bands around 557 cm−1 and 565 cm−1, which corresponds to Fe-O-Fe vibrational modes suggesting the successful formation of iron oxide nanoparticles. The dynamic light scattering technique revealed that the average hydrodynamic size of the MIONPs was 31.96 ± 15.61 nm and 147.40 ± 28.48 nm. Atomic force micrograph and scanning electron micrograph both showed quasi-spherical nanostructures with sizes ranging from 40 to 215 nm. Furthermore, X-ray diffraction and thermogravimetric analyses revealed the crystallinity and thermal stability of the synthesized MIONPs, respectively. This investigation on the effect of precursor concentration provides a valuable insight for the green- mediated synthesis of MIONPs that is vital for various environmental, biomedical, and industrial application.