Hazelnut shell as a valuable bio-waste support for green synthesis of Ag NPs using Origanum vulgare leaf extract: Catalytic activity for reduction of methyl orange and Congo red

In this work the Origanum vulgare leaf extract was used to green synthesis of Ag nanoparticles (NPs) supported on Hazelnut shell as an environmentally benign support. The Ag NPs/Hazelnut shell as an effective catalyst was prepared through reduction of Ag ions using Origanum vulgare leaf extract as the reducing and capping agent and Ag NPs immobilization on Hazelnut shell surface in the absence of any stabilizer or surfactant. According to FT-IR analysis, the hydroxyl groups of phenolics in Origanum vulgare leaf extract as bio-reductant agents are directly responsible for the reduction of Ag ions and formation of Ag NPs. The as-prepared catalyst was characterized by Fourier transform infrared (FT-IR) and UV-Vis spectroscopy, field emission scanning electron microscopy (FESEM) equipped with an energy dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD) and transmittance electron microscopy (TEM). The synthesized catalyst was used in the reduction of Methyl Orange (MO), and Congo Red (CR) at room temperature. The Ag/Hazelnut shell showed excellent catalytic activity in the reduction of these organic dyes. In addition, it was found that Ag/Hazelnut shell can be recovered and reused several times without significant loss of catalytic activity.