Sustainable synthesis of silver nanoparticles using Cynometra ramiflora leaf extract for methyl orange degradation

This study presents an eco-friendly method to synthesize silver nanoparticles (AgNPs) utilizing the leaf extract of Cynometra ramiflora as a bio-reducing agent. A distinct 431 nm surface plasmon resonance signal confirmed the formation of AgNPs. SEM images portrayed uniformly distributed spherical nanoparticles with smooth surfaces. EDX analysis showed a prominent peak at 3 keV, confirming elemental silver. TEM analysis indicated that most AgNPs were 10–25 nm in size, with a mean size of 18.84 nm. XRD confirmed the face-centered cubic nature of the AgNPs. The d-spacing for the (111) plane was found to be 0.2287 nm, in agreement with standard reference values. FTIR analysis demonstrated signals at 3301, 1637, and 843 cm⁻¹, indicating the engagement of functional moieties in reducing and capping the AgNPs. The synthesized AgNPs had a high zeta potential (− 18.2 mV), revealing good stability. The AgNPs demonstrated excellent catalytic potential in the presence of NaBH₄, degrading approximately 95% of methyl orange dye within 15 min, following a pseudo-first-order kinetic model with a kinetic constant of 0.186 min⁻¹.