title: Access to small size distributions of nanoparticles by microwave-assisted synthesis. Formation of Ag nanoparticles in aqueous carboxymethylcellulose solutions in batch and continuous-flow reactors.
abstract: This article examines the effect(s) of the 2.45-GHz microwave (MW) radiation in the synthesis of silver nanoparticles in aqueous media by reduction of the diaminesilver(i) complex, [Ag(NH(3))(2)](+), with carboxymethylcellulose (CMC) in both batch-type and continuous-flow reactor systems with a particular emphasis on the characteristics of the microwaves in this process and the size distributions. This microwave thermally-assisted synthesis is compared to a conventional heating (CH) method, both requiring a reaction temperature of 100 degrees C to produce the nanoparticles, in both cases leading to the formation of silver colloids with different size distributions. Reduction of the diaminesilver(i) precursor complex, [Ag(NH(3))(2)](+), by CMC depended on the solution temperature. Cooling the reactor during the heating process driven with 390-Watt microwaves (MW-390W/Cool protocol) yielded silver nanoparticles with sizes spanning the range 1-2 nm. By contrast, the size distribution of Ag nanoparticles with 170-Watt microwaves (no cooling; MW-170W protocol) was in the range 1.4-3.6 nm (average size approximately 3 nm). The overall results suggest the potential for a scale-up process in the microwave-assisted synthesis of nanoparticles. Based on the present data, a flow-through microwave reactor system is herein proposed for the continuous production of silver nanoparticles. The novel flow reactor system (flow rate, 600 mL min(-1)) coupled to 1200-Watt microwave radiation generated silver nanoparticles with a size distribution 0.7-2.8 nm (average size ca. 1.5 nm).
authors.affiliation: Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan. horikosi@rs.noda.tus.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Horikoshi
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
authors.forename: Kanjiro
authors.initials: K
authors.lastname: Torigoe
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abe
authors.forename: Nick
authors.initials: N
authors.lastname: Serpone
mesh_terms: D002266:Carboxymethylcellulose Sodium / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008872:Microwaves; D010084:Oxidation-Reduction; D010316:Particle Size; D012834:Silver / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D012834:Silver; D002266:Carboxymethylcellulose Sodium