A clear-cut synthesis of silver nanoparticles using glycerol as a multipurpose medium toward catalytic hydrogenation and antibacterial

Adapting for a green and safe protocol, this work developed a straightforward polyol method for synthesizing spherical silver nanoparticles (AgNPs), with a median size of 12.2 nm in glycerol at a low temperature (60 °C). The multipurpose nature of glycerol, acting as both a reductant and an immobilizer, was explored, demonstrating the long-term stability of AgNPs in the resulting colloidal solution. The stability of AgNPs in glycerol was also contrasted with their stability in water and other polyols. The multiple applications of AgNPs in glycerol included their use as antibacterial agents (against both E. coli and S. aureus strains) and as an eco-friendly catalyst. At room temperature, the selective hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) obeyed a pseudo first-order kinetic model, exhibiting a rate constant of 0.1064 min⁻¹. The kinetic and thermodynamic results confirmed that the rate-determining step involved an electron-transfer process from adsorbed hydrogen to 4-nitrophenolate on the AgNPs surface. Utilizing glycerol as a non-toxic solvent, this colloidal AgNPs solution can be easily stored and directly used without any additional purification.