variable frequency microwave synthesis of silver nanoparticles

Systematic studies of silver nanoparticle synthesis in a continuous-flow single-mode microwave reactor using polyol process were performed, revealing that the synthesis is exceptionally effective to give very small metal particles at full reaction yield and very high productivity. Inlet concentration of silver nitrate or silver acetate, applied as metal precursors, varied between 10 and 50 mM, and flow rates ranged from 0.635 to 2.5 dm3/h, to give 3–24 s reaction time. Owing to its much higher reactivity, silver acetate was shown to be far superior substrate for the synthesis of small (10–20 nm) spherical silver nanoparticles within a few seconds. Its restricted solubility in ethylene glycol, applied as the solvent and reducing agent, appeared to be vital for effective separation of the stage of particle growth from its nucleation to enable rapid synthesis of small particles in a highly loaded system. This was not possible to obtain using silver nitrate. All the observations could perfectly be explained by a classical LaMer–Dinegar model of NPs’ formation, but taking into account also nonisothermal character of the continuous-flow process and acetate dissolution in the reaction system. The performed studies indicate an optimal strategy for the high-yield fabrication of metal particles using polyol method.

variable frequency microwave synthesis of silver nanoparticles:

silver nanoparticles of variable morphology synthesized in aqueous foams as novel templates: ..

WongVariable frequency microwave synthesis of ..

Abstract Synthesis of silver nanoparticles based on a polyol process and variable frequency microwave (VFM) was investigated. Comparing to a thermal method, the reaction by VFM radiation was much faster. The effects of silver nitrate concentration, poly(N-vinylpyrrolidone) (PVP) concentration, reaction time and reaction temperature were studied. It was found that the higher concentration of silver nitrate, longer reaction time and higher temperature increased the particle size while the higher concentration of PVP decreased the particle size.

Microwave-assisted synthesis of silver nanoparticles …

While the scores of previous studies focused on establishing effective procedures for the synthesis of specific NPs in batch-type systems, we are familiar with only a few reports on the continuous reaction systems, contributing to the development of synthetic methodologies of metal NPs adaptable to industrial needs (Gold et al. ; Horikoshi et al. ; Nishioka et al. ). Therefore, we deemed it important to carry out more systematic studies of the continuous-flow metal NPs’ synthesis using an originally designed reactor with uniform MW irradiation. In this paper, we report the results of silver nanoparticle synthesis to propose a methodology rather than a direct fabrication procedure, based on understanding the mechanisms of their formation, and not just shear experimental findings. We studied the effects of main process and reaction system variables: precursor type and its concentration, temperature, residence time, and also density of MWs’ power input, on the formation of AgNPs to elucidate the mechanisms of their rapid synthesis. In effect, we identified and clarified some of the observed characteristics of AgNPs using the classical LaMer–Dinegar (LMD) (LaMer and Dinegar ) mechanism of NPs’ formation, but seen from a nonisothermal, continuous-flow perspective. Owing to considerable interest in AgNPs as antibacterial agents, we also examined antibacterial properties of the AgNPs-based suspensions, directly obtained from the reported continuous process.

Variable Frequency Microwave Synthesis of Silver

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biologicalMethods for Silver Nanoparticles ..