High-Throughput Synthesis of Uniform Mg(OH)₂ Nanoparticles in an Oscillating Feedback Minireactor Designed by the Selective Dimension Scale-Out Method

Abstract

Based on a selective dimension scale-out method, a high-throughput oscillating feedback minireactor (OFM) was developed to prepare uniform Mg(OH) 2 nanoparticles using a precipitation method. Three-dimensional unsteady simulations indicated that three secondary flows (i.e., vortex, feedback, and oscillation) could effectively induce chaotic advection, and OFM could improve mixing performance compared to those using the microreactor before amplification. The Villermaux−Dushman experiments showed that high-efficiency micromixing could be achieved within 3.9 ms. The average size of the Mg(OH) 2 nanoparticles decreased with the increase of total flow rate (Q total ), as well as with the decrease of precursor concentration and C(Mg 2+ )/C(OH − ) ratio. Mg(OH) 2 with an average particle size of 53.0 nm and narrow particle size distribution (PSD) was obtained at a high throughput of 180 mL/min. Compared with the products obtained in the initial microreactor, the product quality was maintained or even improved, suggesting that the scale-out method is reliable and effective.

Structure Screening of Oscillating Feedback Microreactors for the High-Throughput Synthesis of Zeolitic Imidazolate Framework-67 Nanoparticles with Controlled Size and Morphology

“…Hence, no clogging of the channel in 1.0-OFM-S could be found owing to the short residence time (i.e., high throughput) and strong fluid shear (i.e., intense chaotic advection). Furthermore, the throughput can be further improved by scaling up the microreactor through the selective dimension scale-out method …”

“…The structure and dimensions of the three OFMs are illustrated in Figure 1, which presents a similar structure to our previous paper. 39,40 The inlet width and feedback channel width are 0.2 and 0.4 mm, respectively. Each of the three OFMs contains a Y-typed inlet, a diverging mixing chamber, and two feedback channels.…”

“…In contrast to the ordered microreactors, it was disclosed that oscillating feedback microreactors (OFMs) based on chaotic advection can operate at high Reynolds numbers (i.e., high throughput, at Reynolds numbers of 10 2 –10 3 ), which is much larger than those of the ordered lamination flow and segmented flow microreactors (i.e., at Reynolds numbers of 10 –1 –10 2 ) . In addition, the three unique secondary flows (i.e., vortex, feedback, oscillation) can effectively induce chaotic advection, causing the fluids to stretch, fold, and compress, significantly shortening the molecule diffusion distance and improving fluid mixing and mass/heat transfer. − Hence, homogeneous concentration and temperature fields could be achieved in OFMs for preparing high-quality nanoparticles with a narrow PSD at high throughput. Lately, we demonstrated that OFMs could be applied for high-throughput production of inorganic nanoparticles, − where small samples with narrow PSD could be effectively prepared.…”

“…In addition, the three unique secondary flows (i.e., vortex, feedback, oscillation) can effectively induce chaotic advection, causing the fluids to stretch, fold, and compress, significantly shortening the molecule diffusion distance and improving fluid mixing and mass/heat transfer. − Hence, homogeneous concentration and temperature fields could be achieved in OFMs for preparing high-quality nanoparticles with a narrow PSD at high throughput. Lately, we demonstrated that OFMs could be applied for high-throughput production of inorganic nanoparticles, − where small samples with narrow PSD could be effectively prepared. However, OFMs have never been used to prepare ZIF-67 or other metal–organic framework materials.…”