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Title: Droplet-based microfluidic method for robust preparation of gold nanoparticles in axisymmetric flow focusing device
Authors: Bandulasena, Monalie V.
Vladisavljevic, Goran T.
Benyahia, Brahim
Keywords: Reaction droplets
Gold nanoparticles
Glass capillaries
Continuous production
Droplet-based micromixer
Droplet microfluidics
Issue Date: 2019
Publisher: © Elsevier
Citation: BANDULASENA, M.V., VLADISAVLJEVIC, G.T. and BENYAHIA, B., 2019. Droplet-based microfluidic method for robust preparation of gold nanoparticles in axisymmetric flow focusing device. Chemical Engineering Science, 195, pp. 657-664.
Abstract: A novel microfluidic mixing strategy was developed and used to prepare polyvinylpyrrolidone (PVP) capped gold nanoparticles (AuNPs). In this process, 1 mM tetrachloroauric acid (HAuCl4) stream containing 1% (w/v) PVP was injected through the inner capillary tube and mixed with 20 mM L-ascorbic acid solution delivered co-currently through the outer coaxial capillary. The reaction mixture was hydrodynamically flow focused by the environmentally friendly oil Miglyol 840 delivered from the opposite side of the outer capillary, which resulted in the generation of reaction droplets in a tapered collection tube. The reactants were rapidly mixed within droplets by internal circulating flows induced by hydrodynamic interactions of fluids inside the droplets with the carrier oil. The size of the prepared AuNPs was measured by both dynamic light scattering and transmission electron microscopy and was found to decrease with decreasing the droplet size and increasing the difference in velocity between the two reactant streams, which improved mixing efficiency within droplets. The smallest nanoparticles were obtained when the outlet section of the injection tube was positioned at the entry section of the collection tube due to the highest shear at the liquid interface. The carrier oil formed a hydrophobic barrier between the droplets and the reactor walls preventing deposition of the synthesised particles. As a result, the size of the AuNPs was smaller than in the co-flow mixer operated with two continuous reactant streams.
Description: This paper is closed access until 9th October 2019.
Sponsor: The microfluidic rig used in the project was purchased from the grant EP/J020184/1, funded by EPSRC, UK.
Version: Accepted for publication
DOI: 10.1016/j.ces.2018.10.010
URI: https://dspace.lboro.ac.uk/2134/35324
Publisher Link: https://doi.org/10.1016/j.ces.2018.10.010
ISSN: 0009-2509
Appears in Collections:Closed Access (Chemical Engineering)

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