Microwave-Assisted Green Synthesis of Silver Nanoparticles (AgNPs) Using Pithecellobium Jiringa Epidermis Extract: Optimization of Irradiation Time And AgNO₃ Concentration

Silver nanoparticles (AgNPs) are widely utilized due to their antimicrobial properties and potential applications in biomedical and environmental technologies. However, environmentally friendly synthesis methods with more efficient reaction times are needed to avoid the use of hazardous chemicals and to reduce lengthy synthesis durations. This study aims to determine the optimal irradiation time and AgNO₃ concentration for producing AgNPs using Pithecellobium jiringa (P. jiringa) seed coat extract as a bioreductant with the microwave irradiation method. The seed coat of P. jiringa contains phytochemical compounds capable of reducing Ag⁺ ions into silver nanoparticles. Microwave irradiation was employed to accelerate the synthesis process by enhancing reaction homogeneity and efficiency. AgNO₃ concentrations of 1 mM, 3 mM, and 5 mM were tested, with 14 minutes identified as the optimal irradiation time. Characterization results showed that the average size of AgNPs at 1 mM AgNO₃ concentration was 96.9 nm, while at 3 mM and 5 mM concentrations, particle sizes significantly increased to 521.7 nm and 3874.5 nm, respectively, due to agglomeration. UV-Vis analysis confirmed the formation of AgNPs with absorption peaks in the wavelength range of 400–450 nm. This study indicates that the optimal conditions for synthesizing small and stable AgNPs are 14 minutes of irradiation and 1 mM AgNO₃ concentration.