Optimization strategy for green synthesis of silver nanoparticles (AgNPs) as catalyst for the reduction of 2,4-dinitrophenol via supported mechanism

Here, we examine the biogenic fabrication of silver nanoparticles (AgNPs) utilizing a simple and environmental friendly method. Silver nanoparticles were synthesized using medicinal plants extracts such as Flamboyant ( Delonix regia ( DRE)) and Moringa oleifera (MOE). The maximum absorbance ( λ max ) of UV–Vis. analysis at 442 and 459 nm indicates the formation of MOEAgNPs and DREAgNPs, respectively. The AgNPs are confirmed by UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Transmission Electron Microscopy (TEM) and XRD techniques. (FT-IR) FT-IR spectra indicate the functional groups of phytochemical compounds in silver nanoparticles (DREAgNPs, MOEAgNPs). The generation of spherical MOEAgNPs and DREAgNPs with a majority particle size of 50 and 100 nm, respectively, was confirmed by TEM analysis. The XRD pattern of AgNPs has FCC form and crystalline lattice at 2θ of 38°, 44°, 64° and 77° corresponding to (111), (200), (220), and (311) reflections of AgNPs. The findings indicate that the ideal conditions for the synthesis process were 2 mMAg + concentration, reaction time is 24 h and 60 °C for extraction. The reduction of 2,4-dinitrophenol to 2,4-diaminophenol using NaBH 4 was carried out under the catalytic influence of AgNPs. The rate constant k (1 st cycle) was found to be 42 × 10 −3 min − 1 and 26 × 10 – 3 min − 1 for the reaction in presence of MOEAgNPs and DREAgNPs, respectively. The recyclability of the prepared AgNPs was tested for 7 cycles without loss in its activity until cycle 5. The activation energy ( E a ) for reduction of 2,4-dinitrophenol that catalyzed by MOEAgNPs or DREAgNPs, respectively, was 36.4 or 31.7 kJmol − 1 . The successes of AgNPs in the catalytic role were supported through DFT studies. Graphical abstract