High‐Yield Synthesis of Silver Nanoparticles by Precipitation in a High‐Aqueous Phase Content Reverse Microemulsion

Abstract

Silver nanoparticles were precipitated at 70°C in a reverse microemulsion containing a high concentration of 0.5 M silver nitrate aqueous solution, toluene as organic phase, and a mixture of surfactants sodium bis (2-ethylhexyl) sulfosuccinate/sodium dodecyl sulfate (2/1, w/w). Nanoparticles were characterized by X-ray diffraction, atomic absorption spectroscopy, and high-resolution transmission electron microscopy. In spite of the high-water/surfactant molar ratio and concentration of silver nitrate solution used in this study, characterizations demonstrated that nanoparticles were silver crystals (purity >99%) with 8.6–8.8 nm in average diameter and 2.9–4.7 nm in standard deviation. It is proposed that slow dosing rate of aqueous solution of precipitating agent and the small molecular volume of toluene attenuated both particle aggregation and polydispersity widening. Experimental yield of silver nanoparticles obtained in this study was much higher than theoretical yields calculated from available data in the literature on preparation of silver nanoparticles in reverse microemulsions.

Synthesis of Silver Nanoparticles by Precipitation in Bicontinuous Microemulsions

“…The phase diagram of the system AOT/SDS (2/1, wt./wt. ), 0.5 M AgNO 3 aqueous solution, and toluene at 70 • C was previously reported by our group [20]. This diagram shows a wide transparent region (1φ), which corresponds to a microemulsion region.…”

New Trends on the Synthesis of Inorganic Nanoparticles Using Microemulsions as Confined Reaction Media

“…Furthermore, the yield of the reactions was as high as 1.16 g of product per 100 grams of microemulsion, which is rather high compared to what can be obtained in most w/o microemulsion systems (0.05 -0.2 grams per 100 g microemulsion). The same research group reported recently the synthesis of silver nanoparticles by the same approach (Reyes et al, 2010;Sosa et al, 2010), by using a microemulsion system based on AOT/SDS as the surfactant system and toluene as the oil. Depending on the surfactant: oil ratio, the authors found the formation of only globular nanoparticles or a mixture of interconnected, worm-like structures plus globular nanoparticles.…”

Effect of silver nanoparticles on human mesenchymal stem cell differentiation

“…Today, Ag-NP are increasingly used because particles with sizes in the range of a few nanometers lead to a dramatic increase in the surface area/mass ratio in contrast to micrometer-sized particles. Such an enlargement of the reactive surface area will lead to the effective release of silver ions (Ag + ) in parallel with low total silver concentrations, resulting in an increased release effect with respect to the applied mass of silver [ 23 – 24 ].…”