Coaxial Injection Mixer for the Continuous Production of Nanoparticles

Abstract

Nanoparticles (NPs) production in batch reactors is limited in terms of reproducibility and control over physical properties such as particle size. Microfluidic techniques and flow-focusing can improve these limitations, but continuous nanoprecipitation through turbulent mixing can also be achieved. This study evaluates the effect of fluid dynamics on NP production and characteristics in a coaxial jet mixer. The results showed that the vertical and horizontal configurations of the mixer impact mixing performance, with buoyancy in the horizontal configuration causing fluid segregation and altering the coaxiality. The mixing performance was tested using water/water and ethanol/water systems with different flow rates, and results indicated that a turbulent jet develops at high values of both the Flow Momentum Ratio (??????) and Reynolds number ( ?? ???? ). The mixing time for the turbulent jet was found to have a clear relationship with the Reynolds number and ?????? and was successfully fitted using a power law equation. Finally, the results showed that the NPs produced in turbulence were smaller and more uniform in size, with a Z-average half that of those produced in laminar conditions. The improved size uniformity and reduced dimensions of the particles resulted in a clearer final product. This study suggests that micromixing is a more favourable method for producing liposomes with improved characteristics and higher productivity compared to interdiffusion.