An efficient microreactor with continuous serially connected micromixers for the synthesis of superparamagnetic magnetite nanoparticles

A new microreactor with continuous serially connected micromixers (CSCM) was tailored for the coprecipitation process to synthesize Fe₃O₄ nanoparticles. Numerical simulation reveals that the two types of CSCM microchannels (V-typed and U-typed) proposed in this work exhibited markedly better mixing performances than the Zigzag and capillary microchannels due to the promotion of Dean vortices. Complete mixing was achieved in the V-typed microchannel in 2.7 s at an inlet Reynolds number of 27. Fe₃O₄ nanoparticles synthesized in a planar glass microreactor with the V-typed microchannel, possessing an average size of 9.3 nm and exhibiting superparamagnetism, had obviously better dispersity and uniformity and higher crystallinity than those obtained in the capillary microreactor. The new CSCM microreactor developed in this work can act as a potent device to intensify the synthesis of similar inorganic nanoparticles via multistep chemical precipitation processes.