Process Intensification on Synthesis of Nanoparticles in a Spinning Disc Reactor The spinning disc reactor with its characteristic fluid dynamics in a thin liquid film on a rotating surface is very potent in gaining access to nanoparticles. To identify the influencing parameters methodically, the micromixing efficiency is determined by the Villermaux-Dushman reaction, a system of competitive parallel reactions. The precipitation of barium sulfate with its fast reaction kinetics and short induction time is used to validate the results. These findings are subsequently applied on the size-selective synthesis of superparamagnetic magnetite nanoparticles via precipitation reaction. Particles size could be controlled in the range between 5 and 10 nm.