Continuous‐Flow Synthesis and Functionalization of Magnetite: Intensified Process for Tailored Nanoparticles

Abstract

The spinning disc reactor (SDR) is used for the size‐selective synthesis and functionalization of nanoscale superparamagnetic iron oxide particles in a single‐step continuous‐flow process. Nanometer‐sized magnetite (Fe3O4) particles are precipitated in a highly sheared thin liquid film on a rapidly rotating disc. A novel liquid‐liquid synthesis is presented whereas control over particle size is reached via adjustable micromixing properties on the disc. The nanoparticles with tailored size, narrow size distribution, and high saturation magnetization can thus meet the special requirements for the use in biotechnological, medical, and catalytic applications. The functionalization of the particles with oleic acid for higher biocompatibility and better dispersibility is accomplished in the SDR in a single step.

Co-precipitation synthesis of stable iron oxide nanoparticles with NaOH: New insights and continuous production via flow chemistry

“…The importance of mixing conditions for the IONP size distribution (with smaller but more monodisperse particles obtained with faster mixing) is well documented [36,37].…”

Unravelling the growth mechanism of the co-precipitation of iron oxide nanoparticles with the aid of synchrotron X-Ray diffraction in solution

“…14,15 For example, Baumgartner et al showed with cryo-transmission electron microscopy (TEM) the formation of amorphous ferrihydrite which attaches to the surface of the growing IONP. 15 However, most co-precipitation syntheses proceed via a single and abrupt increase in pH, which is also the most common approach for large-scale and continuous reactor systems 14,[18][19][20][21] due to the shorter process times. Hence, the understanding of the abrupt pH transitions is extremely important.…”

Small iron oxide nanoparticles as MRI T1 contrast agent: scalable inexpensive water-based synthesis using a flow reactor

“…26,27 Also, fast mixing has been shown to promote the synthesis of small IONPs. [28][29][30] Alternatively, small IONPs for MRI can be produced via rapid (microwave) heating of a FeCl 3 and trisodium citrate solution together with the reducing agent hydrazine. 31,32 The route for IONP T 1 contrast agents to reach market maturity is long and brings challenges, not only for chemists, but also engineers and entrepreneurs.…”