Green Synthesis of Iron (II, III)-polyphenol Nanoparticles and Their Adsorption of Malachite Green.

Three kinds of iron nanoparticles (FeNPs) were prepared via green route based on pomegranate (PG), green tea (GT), and mulberry (ML) extracts under ambient conditions. The obtained materials were characterized by scanning electron microscopy (SEM), transmission electronic microscopy (TEM), X-ray energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) techniques. The experimental results show that FeNPs were in the form of amorphous iron (II, III)-polyphenol complex with different dispersity and morphologies. GT-Fe has the smallest size range of 25–35 nm, PG-Fe has a moderate size-distribution of 30–40 nm, while ML-Fe formed a tuberous net-type with a sheeting structure. PG-Fe displays the highest removal efficiency of 90.2% in 20 min towards cationic dye of malachite green (16.6% by ML-Fe and 69.3% by GT-Fe), which is attributed to its highest polyphenol content, lowest zeta potential, as well as the most Fe²⁺ on the surface of FeNPs. The removal mechanism was mainly induced by electrostatic adsorption based on pH and zeta potential tests. [ABSTRACT FROM AUTHOR]