Mechanistic and kinetic study of the formation of silver nanoparticles by reduction of silver(I) in the presence of surfactants and macromolecules

Abstract

The kinetics of formation of silver nanoparticles by reduction of silver(I) with galactose were studied spectrophotometrically in the presence of surfactants and chitosan as stabilizing agents. The reaction was carried out under pseudo-first-order conditions by using a tenfold excess of [galactose] over [Ag+]. The effects of cetyltrimethylammonium bromide (cationic surfactant) and sodium dodecyl sulfate (anionic surfactant) on the reaction rate have been studied. Chitosan inhibits the rate of reaction by up to 70 %. TEM imaging shows that there is no aggregation of silver nanoparticles in the presence of chitosan. The rate of reaction increases with increasing [OH-]. A mechanism for the reaction is proposed, and the rate equation derived from this mechanism was consistent with the experimental behaviors. Thermodynamic activation parameters were calculated.