Essential oil analysis of Rhaponticum repens (L.) Hidalgo, and its application in green synthesis of iron nanoparticles to remove Cr (VI) ions from aqueous solutions

Abstract

Acroptilon repens is a widespread weed in Asia, and has a complicated taxonomy. Recent taxonomical treatment explored that Acroptilon species must be classified in the genus Rhaponticum. Therefore, the scientific name of this species has been converted into Rhaponticum repens. In the current study, essential oil composition, and its ability to green synthesis of iron nanoparticles for future use to adsorb Cr (VI) ions pollution of aquatic solution were evaluated for the first time. The GC-MS analysis revealed oxygenated monoterpenes constituted great proportion of the essential oil, with 1,8-cineole and camphor as the main essential oil components. Several appropriate methods, including UV-Vis, FTIR, XRD, SEM, DLS, and VSM revealed the green synthesis of a mixture of Fe₃O₄ and Fe₂O₃ nanoparticles by the extracted essential oil. Sizes of the produced nanoparticles were not equal and detected in the range of 3 to 50 nm, with an average size of 31.5 nm and the magnetic property of 15 emu/g. The green-synthesized nanoparticles could adsorb Cr (VI) ions pollution from aquatic solutions. However, under an optimum condition, the Cr (VI) ions adsorption capacity and removal were 167.6 mg/g and 91%, respectively. Findings revealed the major essential oil composition highly differed from those reported in the previous phytochemical studies. Although the synthesized nanoparticles were not uniform, they could remove Cr (VI) ions pollution.

Keywords:

• Essential oil
• R. repens
• Green synthesis
• Iron oxide
• Cr (VI) adsorption