Study on the fabrication of microfluidic crystallizers for the high temperature crystallization and the temperature-swing crystallization

Abstract

In this study, we designed and fabricated the micro- and milli-fluidic crystallizers as solutions to the conventional crystallizers which are essential unit process in various industries such as pharmaceuticals, food, and fine chemistry but have limitations of heat and mass transfer. Firstly, we fabricated bolt-nut microfluidic reactor that overcomes the limitations of temperature and solvent usage in conventional miroreactors. The economic feasibility of reactor fabrication was considered by employing only lathe process for reactor fabrication. $CuInS_2$ quantum dots were synthesized with the bolt-nut microfluidic reactor demonstrated improved size uniformity and narrower photoluminescence wavelength compared to quantum dots synthesized with a batch reactor. By controlling the precursor concentration and the size of the quantum dot core, the emission wavelength of the quantum dots was adjusted from 525 nm to 730 nm. Secondly, a temperature swing milli-fluidic crystallizer in the form of milli-fluidic channels wrapped around a Peltier device was fabricated to control the size distribution and average size of the crystals. It was observed that the temperature swing crystallization method yielded a narrower crystal size distribution compared to simple cooling crystallization. Optimization of process conditions such as temperature difference, flow rate, and heating-cooling time ratio was conducted. Lastly, temperature swing milli-fluidic crystallizer with attrition was applied to accelerate the deracemization of sodium chlorate crystals. The optimal conditions for fastest deracemization such as temperature difference and time ratio between temperature swing and attrition were optimized.