Magnetite-Silica core-shell nanocomposites decorated with silver nanoparticles for enhanced catalytic reduction of 4-nitrophenol and degradation of methylene blue dye in the water

Abstract

In this study, we synthesized multifunctional Fe3O4@SiO2/Ag magnetic nanocomposites (MNCs) by in situ method with an average size of 583 ± 4 nm. At different temperatures and pH, the catalytic properties of as-prepared MNCs were investigated for the degradation of methylene blue (MB) dye and reduction of 4-nitrophenol (4-NP) in an aqueous solution. The Fe3O4@SiO2/Ag MNCs were capable to remove 96.5% and 97% of MB and 4-NP respectively from aqueous media. The as-prepared MNCs were characterized by using Transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering analysis (DLS), Energy dispersive X-rays analysis (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible diffuse reflectance spectra (UV-vis DRS) and vibrating sample magnetometery (VSM). The rate constant for 4-NP and MB were calculated which were 0.385 ± 0.002 and 1.58 ± 0.09 min-1 respectively. The values of thermodynamics parameters enthalpy, Gibbs free energy, Entropy and activation energy were calculated for both MB and 4-NP. This nanocomposite exhibited easy synthesis, cost effective, high stability and fast separation using external magnet.