Kinetics and mechanism of the formation of silver nanoparticles by reduction of silver (I) with maltose in the presence of some active surfactants in aqueous medium

摘要

The kinetics and mechanism of the formation of silver nanoparticles by reduction of Ag~+ with maltose were studied spectrophotometrically by monitoring the absor-bance change at 412 nm in aqueous and micellar media at a temperature range 45-60 °C. The reaction was carried out under pseudo-first-order conditions by taking the [maltose] (>tenfold) the [Ag~+]. A mechanism of the reaction between silver ion and maltose is proposed, and the rate equation derived from the mechanism was consistent with the experimental rate law. The effect of surfactants, namely cetyltrimethylammonium bromide (CTAB, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic surfactant), on the reaction rate has been studied. The enthalpy and the entropy of the activation were calculated using the transition state theory equation. The particle size of silver sols was characterized by transmission electron microscopy and some physiochemical and spectroscopic tools.