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Continuous synthesis of plate-like silica microparticles using microfluidics


The synthesis of plate-like silica particles, which are of importance for a variety of applications, are mainly based on the widely adopted method of the sol-gel reaction of silicon alkoxides in traditional batch-wise instrumentation. In this study, continuous-flow synthesis of amorphous plate-like silica particles is reported through combining droplet-based microfluidics and the sol-gel reaction of tetraethyl orthosilicate. The reaction was conducted at the surface of oil droplets, comprising tetraethyl orthosilicate (TEOS), suspended in acidic (HCl) water, resulting in silica particles on the surface of the droplets, leaving the device with outlet flow. The synthesized particles had plate-like structure with thickness less than 1 μm and microscale in two other dimensions. The influences of experimental parameters (TEOS and HCl concentrations and the flow rate of aqueous phase) on the silica production rate were examined. With increase in the TEOS and HCl concentrations, the production rate increases monotonically. With increase in the flow rate of aqueous phase, the production rate increases up to a specific flow rate. Beyond the flow rate, the production rate decreases with increase in the flow rate. A phenomenological model is proposed to address the production rate using the droplet-based microfluidic system. In addition, response surface methodology (RSM) was used to statistically model and optimize the production rate. At optimum values for the experimental parameters, the experimentally measured production rate was considerably comparable to that predicted by RSM.

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Correspondence to Aliasghar Mohammadi.

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Tamtaji, M., Mohammadi, A. Continuous synthesis of plate-like silica microparticles using microfluidics. J Flow Chem 9, 161–174 (2019).

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