Green synthesis of silver nanoparticles using pomegranate peel extracts and its application in photocatalytic degradation of methylene blue

Background: Nanoparticles (NP) have been shown to have various useful applications. They are generally synthesized using chemical processes involving hazardous chemicals. Therefore, green synthesis of NPs using natural products can be an environmentally friendly alternative. Objectives: In this study, green synthesis of silver NPs (AgNPs) using pomegranate (Punica granatum) peel extract (PE) and its application in photocatalytic degradation of methylene blue (MB) dye were examined. Methods: PE-mediated AgNP synthesis was studied using different analytical methods, including ultraviolet-visible (UV-VIS) spectroscopy (surface plasmon resonance or SPR), X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), and Fourier-transform infrared spectroscopy (FTIR). Photocatalysis of MB dye was studied in the presence of synthesized NPs. Results: The color changes, UV-VIS spectra (SPR at around 442 nm within less than five minutes), XRD peaks (2θ: 38.18, 44.31, 64.61, and 77.50), FE-SEM-EDX data, and FTIR spectra confirmed the presence of AgNPs. PE-mediated AgNPs showed a high zeta potential (-68.93mv),with an average particle size of 57.7 - 142.4 nm. The phytoconstituents of PE could act as both reductants and stabilizers. Photocatalytic degradation of MB dye was spectrophotometrically monitored using PE-mediated AgNPs as catalysts under sunlight irradiation. The absorbance of MB (2.557) was observed at 660 nm, which was reduced to almost 55 - 60% within one hour and degraded to almost 89% by 48 - 72 hours. Conclusions: AgNPs were rapidly synthesized within five minutes using pomegranate PE, which could degrade almost 89% of MB dye within 48 - 72 hours under sunlight irradiation; this finding indicates the potential of this natural product, although further exploration is needed.