Green synthesis of silver nano-particles (AgNPs) from flowers of Rhododendron campanulatum and its potential applications as photo-catalyst and antioxidant

Abstract

The present work demonstrates the Green synthesis of silver nano-particles (AgNPs) using the Rhododendron campanulatum flower extract and their potential applications as photo catalyst and antioxidant. Several spectral approaches viz., UV-Vis, XRD, SEM-EDAX, BET isotherm and TEM were used to characterise the biosynthesized AgNPs in detail.The UV-Vis spectroscopy showed that the biosynthesized AgNPs have surface plasmon resonance (SPR) peak at 472 nm. The X-ray diffraction (XRD) studies confirmed the crystalline nature of biosynthesized AgNPs with mean crystalline size ~22.97 nm. According to the TEM examinations, the synthesized AgNPs were poly dispersed, smooth in morphology, irregularly shaped, and had an average grain size of 43.75 nm. The adsorption studies showed that the biosynthesized AgNPs have the single point surface area (at P/Po) was 0.1398 m2/gm, BET surface area was 0.1057 m2/gm, Langmuir surface area was 0.1465 m2/gm, and the micro pore area was 0.7834 m2/gm. The antioxidant efficacy of as synthesized AgNPs was determined using DPPH scavenging method, and the IC50 value was observed 38.68 μg/mL. Photocatalytic activity of synthesized AgNPs was determined by studying the adsorption/desorption equilibrium between the AgNPs and the solutions of MB, and RB dyes. The synthesized AgNPs showed the dye degradation efficacy of 73.88% for methylene blue (MB) dye, and 76.62% for Rose Bengal (RB) dye; however, in the absence of AgNPs, the degradation efficacy was observed as17.55% and 48.80% in 4 hours under photo-irradiation for MB and RB dye, respectively.