Waste upcycling of Citrus sinensis peels as a green route for the synthesis of silver nanoparticles

Abstract

ABSTRACTThe present study reports a rapid one-step green synthesis of silver nanoparticles (AgNPs) using hot water extract of Citrus sinensis (sweet orange) peels. A visible color change was observed from faint yellow to brown, upon the bioreduction of silver nitrate with peels’ extract and then the stabilization of the synthesized AgNPs. The UV–Vis spectrophotometric analysis proved the characteristic absorption peak λmax 422 nm of AgNPs. The one-factor-at-a-time-optimization technique was used to study the effect of the key factors governing the synthesis of AgNPs, including temperature, illumination, pH, different concentrations of peels’ extract and silver nitrate, mixing rates, and reaction time. The average particles size was measured by dynamic light scattering (DLS) and revealed 23.81 nm. The zeta potential value of −20.3 mV proved the stability of the synthesized AgNPs. Energy-dispersive X-ray (EDX) confirmed the strong signals for elemental silver. The X-ray diffraction confirmed the crystalline nature of the biosynthesized AgNPs with an average size of 15 nm. Fourier transform infrared (FTIR) spectroscopy identified the possible functional groups involved in capping and efficient stabilization of the synthesized AgNPs. Field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscope (HRTEM) revealed the spherical-shaped AgNPs with an average size of 3–12 nm.