Green synthesis of magnetically recoverable Fe3O4/HZSM-5 and its Ag nanocomposite using Juglans regia L. leaf extract and their evaluation as catalysts for reduction of organic pollutants.

In this work, an Fe3O4/HZSM-5 nanocomposite was synthesised in the presence of Juglans regia L. leaf extract. Then, silver nanoparticles (Ag NPs) were immobilised on the surface of prepared magnetically recoverable HZSM-5 using selected extract for reduction of Ag+ ions to Ag NPs and their stabilisation on the surface of the nanocomposite. The reduction of Ag+ ions occurs at room temperature within a few minutes. Characterisation of the prepared catalysts has been carried out using fourier transform infrared (FT-IR), X-ray diffraction, field-emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy, Brunauer-Emmett-Teller method, and a vibrating sample magnetometer. According to the FESEM images of the nanocomposites, the average size of the Ag NPs on the Fe3O4/HZSM-5 surface was >70 nm. The Ag/Fe3O4/HZSM-5 nanocomposite was a highly active catalyst for the reduction of methyl orange and 4-nitrophenol in aqueous medium. The utilisation of recycled catalyst for three times in the reduction process does not decrease its activity.