Facile green chemistry approach for environmental remediation: catalytic removal of toxic compounds and pathogens from water using Hyptis capitata plant mediated iron nanoparticles.

Green synthesis of iron nanoparticles (FeNPs) has gained more interest among researchers because it is an eco-friendly method that avoids harmful chemicals as stabilizing agents. These nanoparticles have been widely used for the degradation of pollutants and bacterial growth inhibition without affecting mammalian cells. In this study, FeNPs were prepared using an unconventional technique with Hyptis capitata (HC) leaf extract as both reducing and capping agent through the microwave method. The formation was confirmed by the color change of the reaction mixture and the characteristic UV-visible absorption peak obtained at 294 nm. The FT-IR interpretation shows the involvement of plant phytochemicals in the reduction and capping of nanoparticles. A broad and diffuse hump obtained in the X-ray diffraction (XRD) spectrum identifies an amorphous structure, and the zeta potential value (-30 mV) confirmed colloidal stability. Thermo-gravimetric analysis determined the thermal stability and degradation pattern of nanoparticles. The dynamic light scattering analysis of FeNPs confirms monodisperse particle size distribution. HR-TEM analysis proves the presence of spherical FeNPs with an average size of 3-6 nm, and the SAED pattern signifies the amorphous nature of FeNPs in the colloid. The EDX spectrum confirmed the presence of elemental iron. FeNPs demonstrated bacterial growth inhibition against Staphylococcus aureus and Escherichia coli, along with the catalytic efficiency to remove methyl orange and 4-nitrophenol from aqueous systems. These results reveal the potential of HC leaf extract-mediated FeNPs as a functionalized biomaterial for environmental remediation.