Preparation of Barium Sulfate Nanoparticles in an Interdigital Channel Configuration Micromixer SIMM-V2

BaSO4 nanoparticles were synthesized by precipitation of Na2SO4 and BaCl2 at their concentrations close to their saturation concentrations in a commercially available micromixer, SIMM-V2. The particle size of BaSO4 was dependent on the flow rate at the saturation concentrations, exhibiting a Z-type change with increasing the flow rate. The average particle size of BaSO4 particles could be adjusted by decreasing the Na2SO4 concentration. Decreasing the molar ratio R to less than 1 resulted in agglomerated round BaSO4 particles, while dispersible rod-like ones were produced when R = 1.2–1.8. The wastewater separated from each synthesis solution could be reused to prepare the BaCl2 solution, resulting in a slight increase in the mean particle size and broadened particle size distribution after eight cycles. The optimized preparation process could produce 2 kg/h of BaSO4 nanoparticles with a mean particle size of 28 nm with a narrow particle size distribution.