Catalytic degradation of methylene blue dye and antibacterial activity of biosynthesized silver nanoparticles using Peltophorum pterocarpum (DC.) leaves

Abstract

We report the use of the aqueous extract of Peltophorum pterocarpum leaves (PPLE) as a source of relatively cheap and readily accessible reducing- and stabilizing agents for the biosynthesis of silver nanoparticles (AgNPs). The biosynthesis was conducted at 80 °C and pH 9 within 45 min. The FTIR and UV-vis spectroscopic characterization of the PPLE provided evidence of chromophores with functional groups characteristic of polyphenolic compounds. These associated functional groups were also observed in the FTIR spectrum of the AgNPs which suggested their influence on the stabilization of the AgNPs. Similarly, the SEM micrograph and TGA thermogram indicated the presence of PPLE phytoconstituents on the surface of the synthesized AgNPs. The crystalline nature of the AgNPs was noted by the rings in the SAED obtained from HRTEM, which also showed the AgNPs as spheres and ellipses with sizes in the range of 2–50 nm. The AgNPs showed good catalytic activity in the degradation of methylene blue dye with a pseudo-first-order rate constant of 0.3378 min⁻¹. The degradation was completed within 6 min. In addition, the AgNPs displayed improved antibacterial activities in comparison with the PPLE against selected clinical pathogens. Based on our findings in this study, the AgNPs can serve as a potential catalyst in water treatment and also as an antimicrobial agent in disinfectant formulations.