Microwave assisted green synthesis of silver nanoparticles from Carica papaya fruit extract: Characterization and detection of Fe3+ and Hg2+ ions

Abstract

For the past decade, biological synthesis of nanoparticles has been on the rise due to its nontoxic, ecofriendly approach and their potential applications in diverse fields. In the present study, a green route was employed to synthesize AgNPs using the extract of raw papaya as the reducing and capping agent via Microwave assisted method. The synthesized CP-AgNPs are characterized by Ultra Violet-Visible Spectroscopy, FTIR Spectroscopy, XRD, SEM-EDX, TEM, SAED, Zeta Potential (ζ) and XPS. The formation of AgNPs was verified by UV–Visible spectroscopy with an absorption maxima at 410 nm. The FTIR spectra revealed the presence of phytochemicalsresponsible for carrying out the reduction and capping of AgNPs. The morphology, shape andsize were examined by SEM and TEM techniques. The particles were found to be spherical in shape with an average diameter of 8.48 ± 2.48 nm. EDAX spectra confirmed the presence of Carbon, Nitrogen, Oxygen and Silver. XRD and SAED results confirmed the crystalline nature of the CP-AgNPs and revealed the FCC structure of the nanoparticles. Zeta potential (ζ) was measured at five different pH values to define the stability of the nanoparticles and the results indicated that the bio-synthesized CP-AgNPs are stable over a range of pH values ranging from 2 to 11 with zeta potential values ranging from −12 mV to −52 mV. The near surface composition and chemical state of the nanoparticles was interpreted using XPS. The CP-AgNPs were then used to detect metal ions in aqueous solution. Fe3+ and Hg2+ metal ions were successfully detected. Thus, the result of this study shows that silver nanoparticles synthesized using raw papaya extract are stable and have potential applications as a sensor for Fe3+ and Hg2+ detection.