Chemical Engineering

Efficiency of the multiphase process systems mainly depends on the interfacial area available in the systems for the transport of targeted molecules. Miniaturization is one of the novel techniques which can used to enhance the process efficiency up to 95% by increasing the interfacial area for the molecular transport. In our studies, efficiency of more than 90% has been achieved in miniaturized droplet flow multiphase reactive extraction systems where the citric acid from dilute aqueous solutions was extracted to Trioctylamine-Decanol system in circular mesoscale channels. Similar process carried out in many conventional systems have achieved efficiencies less than 30% only. The miniaturized mesoscale droplet flow systems consisted of channels with 0.9 mm diameter and 10 mm length with phase mixer having confluence angle of 120^o and total flow rate of 20 mL/h. The phase mixer used in the process was fabricated using Polydimethylsiloxane (PDMS) polymer by gravity casting. The system was offering higher efficiencies even at higher flowrates with a nominal increase in the length of the channels. In addition, the phase separation in the high-volume systems is highly energy oriented and time consuming and generally accompanied with a lot of process problems. The miniaturized multiphase systems also offer an easy, cost effective and rapid in-situ phase separation using phase splitter working on the principle of unequal wetting of different surfaces by individual phases in flowing fluid mixture. The experiments with PDMS- glass based phase splitter for the separation aqueous phase from the organic phase in the above system was delivering 90% phase separation efficiency at total flow rates as high as 120 mL/h. However, a single miniaturized system limits the process volumes to very lean level and is a challenge in using the same when a large process output is expected. But the highly efficient low volume systems can be scaled out to large number of modules to accomplish higher process outputs required in commercial operations.