Synthesis of Silver Nanoparticles Using a Microfluidic Impinging Jet Reactor

Abstract

Synthesis of silver nanoparticles (NPs) in an impinging jet reactor (IJR) was investigated due to its unique properties of efficient mixing and lack of channel walls which avoid fouling. Silver NPs were formed at room temperature by reducing silver nitrate with sodium borohydride in the presence of sodium hydroxide. Two types of ligand were used to stabilize the NPs, trisodium citrate, and polyvinyl alcohol (PVA). Weber number, the ratio between inertial forces and surface tension forces, is used to characterize flow in impinging jets. Flow regimes were investigated for Weber numbers in the range of 13-176. A liquid sheet/chain regime was identified at lower Weber numbers (<90), and an unstable rim structure was identified at higher Weber numbers (>90). Mixing time was found to be in the range 1-7 ms, using the Villermaux-Dushman reaction system and interaction by exchange with the mean mixing (IEM) model. Fastest mixing occurred at Weber number ca. 90. Using trisodium citrate as a ligand, NP size decreased from 7.9 ± 5.8 nm to 3.4 ± 1.4 nm when flow rate was increased from 32 mL/min to 72 mL/min using 0.5 mm jets, and from 6.4 ± 3.4 nm to 5.1 ± 4.6 nm when flow rate was increased from 20 mL/min to 32 mL/min using 0.25 mm jets. Using PVA as a ligand, NP size decreased from 5.4 ± 1.6 nm to 4.2 ± 1.1 nm using 0.5 mm jets and stayed relatively constant between 4.3 ± 1 nm and 4.7 ± 1.3 nm using 0.25 mm jets. In general, the size of the NPs decreased when mixing was faster.

Sensing of circulating cancer biomarkers with metal nanoparticles

“…Recent advances in their synthesis include the use of microfluidic reactors for continuous growth of the particles. 79,94 AgNPs have bluer LSPR bands than AuNPs and stronger field enhancements. 95 Thus, since the publication of the early synthetic protocols, AgNPs were successfully used as a substrate for SERS.…”

Silver Nanoparticle Synthesis Using an Inkjet Mixing System

“…B z enabled higher We and better mixing by rotation and resulted in d av 2.5 nm at We 39.1. Baber et al reported using a clog-free microfluidic impinging jet microreactor to synthesize very small AgNPs and obtained AgNPs that was approximately d av 4.1 nm at We 65.0 (Baber et al, 2016). IMS enabled the synthesis of even smaller AgNPs, which indicated the significant potential of IMS.…”

Liquid sheet characteristics of two impinging jets with different diameters

“…This technique can be applied for atomization of the high viscosity and non-Newtonian liquids such as the gelled fuels because of its simplicity and high-performance mixing and atomization [3]. In chemical reactors, impinging of two jets can be used in crystallization and precipitation process [4], [5], synthesis of silver nanoparticles [6], and forming clathrate hydrates [7]. Impinging jets also can be developed with the UV/H 2 O 2 reactors for wastewater treatment [8].…”