Scalable fabrication of uniform BaSO4 nanoparticles through flash nanoprecipitation in a multi-inlet vortex mixer (MIVM)

Herein, the flash nanoprecipitation (FNP) technique, which enables the highly efficient mixing of aqueous barium (Ba 2+ ) and sulfate (SO 4 2− ) in a multi-inlet vortex mixer, is adopted for the scalable fabrication of barium sulfate nanoparticles in a well-controlled manner. Barium sulfate nanoparticles with an average size of 40 nm and a narrow size distribution (polydispersity = 0.18) are successfully produced at a yield of 0.7 kg/h. The size of the fabricated nanoparticles decreases and uniformity enhances with an increase in the volumetric flow rate, feeding concentration, and initial molar ratio between Ba 2+ and SO 4 2− . Moreover, mechanisms underlying this trend are investigated; FNP's sub-millisecond mixing at high volumetric flow rates, combined with a high nucleation-to-growth rate ratio under elevated supersaturation, and the stabilizing effect of excess Ba 2+ , are crucial for producing high-quality BaSO 4 nanoparticles. Our results demonstrate the FNP technique to be promising for the industrial production of inorganic nanoparticles.