Optimisation of significant parameters through response surface methodology in the synthesis of silver nanoparticles by chemical reduction method

Abstract

Response surface methodology coupled with the central composite design (CCD) was employed to optimise the significant parameters in the synthesis of silver nanoparticles (AgNPs) by chemical reduction method to obtain smaller average particle size. Different parameters such as the ethylene glycol (EG) concentration as reducing agent, the polyvinyl pyrrolidone (PVP) content as stabiliser and the pH were selected as they have the dominant effects on the particle size of AgNPs. Each of these parameters was studied at three levels. The average particle size of AgNPs was considered as the response value and determined by dynamic light scattering (DLS) analysis. The statistical analysis showed that the pH emerged as the most significant parameter influencing the average particle size and after that, the PVP content was also a significant parameter. The AgNPs synthesised under optimal conditions (6.88 M of EG, 0.5% of PVP and pH = 11) were characterised by UV–vis spectroscopy, X-ray diffraction (XRD), DLS, zeta potential, field emission scanning electron microscope and energy dispersive X-ray analysis. The XRD pattern showed the face-centred cubic silver and the average crystallite size of AgNPs was 30 nm. The average particle size of AgNPs was 37.35 nm according to DLS analysis, which was in good agreement with the predicted value (37.65 nm) by CCD.