Silica-Coated Magnetic Nanocomposite Decorated with Green Synthesized Silver Nanoparticles for the Potential Application as a Catalytic Agent

In the present study, magnetite nanoparticles were first coated with silica nanoparticles (Fe۳O۴/SiO۲) shells. Next, silver nanoparticles (Ag-NPs) were successfully decorated on the surface of the Fe۳O۴/SiO۲ nanocomposites (Fe۳O۴/SiO۲/Ag). Fe۳O۴/SiO۲ and Ag NPs were synthesized via a typical hydrothermal procedure and a green-friendly approach. An aqueous extract of garden cress leaves (Lepidium sativum) was used to prepare Ag-NPs. The obtained Fe۳O۴/SiO۲/Ag nanocomposites were examined by analysis assays including Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Fourier Transform InfraRed (FT-IR) analysis, Vibrating Sample Magnetometer (VSM), and Thermal Gravimetric Analysis (TGA). Further, the Fe۳O۴/SiO۲/Ag nanocomposites were investigated for catalytic activity through the reduction reaction using sodium borohydride (NaBH۴) as a reductant agent. In the typical reaction, ۴-nitrophenol (۴-NP) was reduced to ۴-aminophenol (۴-AP) by using Fe۳O۴/SiO۲/Ag as a catalyst. The kinetic modeling of the reduction process revealed that a pseudo-first-order equation best described the reduction reaction pattern. We found that the Fe۳O۴/SiO۲/Ag catalyst can be directly removed from the reaction medium by an external magnet. Notably, the separated Fe۳O۴/SiO۲ /Ag can be used as a catalyst for several reactions. The effective reuse  of the Fe۳O۴/SiO۲/Ag catalyst was achieved up to four times, with about ۸۵% of recovery under our experiments.

کلیدواژه ها:

Silica-coated Magnetite nanoparticle ، Silver nanoparticles ، Garden cress extract ، Catalyst