Methylene Blue Degradation Over Green Fe3O4 Nanocatalyst Fabricated Using Leaf Extract of Rosmarinus officinalis

To exploit the high catalytic capabilities of nanoparticles in dimensions below 10 nm due to its increased activity, catalytic degradation of methylene blue (MB) on green nano-Fe3O4 was studied. In this regard, Fe3O4 nanoparticles (Fe3O4-NPs) were fabricated with a rapid, one-step and biosynthesis pathway in which Rosmarinus officinalis extract containing rosmarinic acid and sulfated polysaccharides acted as the main reducing and stabilizing agent for reducing ferric chloride. For characterization purposes, the XRD identified the distinctive peaks related to the inverse spinel structure of Fe3O4 nanoparticles. In addition, the superparamagnetic properties of the nanoparticles are determined by the VSM. TEM analysis of Fe3O4 nanoparticles showed spherical morphology with a size of 2.5–6.5 nm. The band around 364 nm in the UV–Visible spectroscopy indicated the excitation of valence electrons of Fe3O4-NPs. Subsequently, the Fenton-like catalytic activity of these nanoparticles was investigated by designing a detailed experiment and analyzing the degradation and removal of MB from the solution using rapid UV–Vis (calibrated with standard MB solutions) analysis. It was found that there was a significant interaction between catalyst and H2O2 additive. Although nanoparticles alone were able to remove about 65