PREPARATION OF COLLOIDAL SILVER NANOPARTICLES ASSISTED BY MICROWAVE IRRADIATION AND THEIR STABILITY DURING STORAGE.

Colloidal silver nanoparticles were synthesized using chitosan as a stabilizing agent and a reducing agent, assisted by microwave irradiation. It is a new strategy on synthesis via gel phase using sodium hydroxide (NaOH) as an accelerator with silver nitrate (AgNO3) as a salt precursor. UV-Vis spectrophotometer was used to investigate silver nanoparticles formation indicating the appearance of the Localized Surface Plasmon Resonance (LSPR) phenomenon. The size and shape of silver nanoparticles were characterized by Transmission electron microscopy (TEM). Silver nanoparticle stability was investigated based on the LSPR phenomenon and colloidal viscosity during storage for 16 weeks at ambient and low temperatures. The absorption peak at about 400 nm of UV-Vis spectra proved that the silver nanoparticles had been formed. The amount of accelerator NaOH, time of microwave irradiation, and AgNO3 concentration affected the intensity of peak absorption. Based on the TEM image, the size of silver nanoparticles is about 3 - 7 nm with spherical shape. The colloidal of silver nanoparticles were stable for 16 weeks after preparation with neglected aggregation. Storage on low temperature for 16 weeks showed better stability of colloidal silver nanoparticles than that at ambient temperature based on LSPR phenomenon. [ABSTRACT FROM AUTHOR]