LAUSR

Abstract Superparamagnetic Fe 3 O 4 nanoparticles coated with Green Tea Polyophenols (GTP), i.e. Fe 3 O 4 @GTPs NPs were synthesized by wet-chemical method with eco-friendly and environmentally benign approach. The coated NPs were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and field emission scanning electron microscopy (FESEM) equipped with energy dispersive spectroscopy (EDS). These analyses revealed that the particles were of uniform shapes and sizes of 10 ± 3 nm with a coating of GTPs. The vibrating-sample magnetometer (VSM) measurement of the coated sample demonstrated a saturation magnetization of 61emu/g with negligible coercivity (∼0.001 T) and retentivity (∼0.9 emu/g) indicating superparamagnetic behavior the NPs at room temperature. The synthesized NPs were highly stable and well-dispersed in aqueous medium through their hydrophilic coating of GTPs. These particles showed high adsorption capacity (7.25 mg/g) for removal of methylene blue (MB) dye in wastewater treatment. The sorption dynamic and equilibrium data were in good agreement with the pseudo-second-order kinetic and Langmuir isotherm models respectively. In addition, the particles could be easily separated from the liquid medium through magnetic separation and potentially reused in multiple cycles.