This study subjected the essential oil extracted from the aerial parts of the Russian knapweed plant, sourced from natural habitats in Markazi Province, Iran, to rigorous analysis. The Clevenger method facilitated the extraction, and standard laboratory techniques, including gas chromatography-mass spectrometry (GC–MS), were employed for quantitative and qualitative chemical compound identifcation. The reducing and stabilizing capabilities of the extracted essential oil were evaluated for the frst time during a surfactant-free nano-emulsion system in the synthesis of iron oxide nanoparticles as a green and environmentally-friendly approach. The characteristics of the synthesized nanoparticles were comprehensively explored using conventional methods such as XRD, SEM, DLS, and VSM. The efciency of the essential oil extraction was estimated to be 0.11%, and the gas chromatograph identifed twenty-one chemical compounds, constituting 67.38% of the total essential oil. The major constituents included 1,8-cineole (17.18%), camphor (16.32%), beta-caryophyllene (14.14%), caryophyllene oxide (10.99%), and alpha-pinene (8.75%). The study chose 4:1 ratio of the organic phase (essential oil) to the aqueous phase with the smallest emulsion droplet size for synthesizing the iron oxide nanoparticles. The X-ray difraction (XRD) results indicated successful formation of the mixture of iron oxides (Fe3O4 and Fe2O3) through the prepared nano-emulsion reactor. SEM, DLS, and VSM analyses conducted at 200 °C for 2 h revealed the key characteristics of the prepared nanoparticles, including an average particle size of 12.3 nm, a surface charge of+19.26 mV, and a magnetic property of 30 emu/g, respectively. These fndings underscore the potential of the essential oil of Russian knapweed as a green and environmentally-friendly agent in the synthesis of iron oxide nanoparticles.
