Formation of lithium carbonate nano-particles using a massively arrayed microfluidic fiber reactor

Abstract

Microfluidic-based nanoprecipitation is an important tool in modern process intensification to form nanoparticles with well controlled size, size distribution and surface properties. Lithium carbonate nanoparticles were formed continuously with controlled size distribution in the present work using a vertical microfluidic fiber contactor/reactor. The reactor operates as an industrially relevant massively arrayed microfluidic environment which can be scaled for high throughput. Lithium carbonate nanoparticles are an important intermediate for the mining, recycling and production of lithium ion for batteries, pore formers for fuel cell catalysis, and even in pharmaceuticals. Formation of such nanoparticles in a microfluidic environment has the potential for elegant control of polydispersity, and for the fiber contactor/reactor the micro-environment is massively arrayed and high throughput is simultaneously possible. Continuous microfluidic fractional precipitation of lithium carbonate nanoparticles with diameters as small as 5.9 nm is described. The solvent was a CO2-saturated water solution and the anti-solvent was isopropanol. The effects of process parameters (including temperature, surfactant concentration, antisolvent strength, and process flowrate) on product size and polydispersity were examined. In particular, lower temperatures seemed to produce low polydispersity. The product was characterized using dynamic light scattering (DLS). A computational fluid dynamics model is also presented to predict the nucleation point (along the length of the reactor) where nanoparticles were likely forming. Correlation to crystal growth mechanisms in the reactor and the importance of reactor length (Otswald versus digestive ripening) is discussed, residence time being one potential contributing factor to the low polydispersity.