A microfluidic study of liquid-liquid extraction mediated by carbon dioxide

Area of Science:

• Chemical Engineering
• Separation Science
• Microfluidics

Background:

• Liquid-liquid extraction is crucial for separation and purification but faces challenges in energy-intensive solvent recovery.
• Switchable solvents reacting with carbon dioxide (CO2) offer a promising solution to reduce energy consumption and environmental impact in solvent recovery.

Purpose of the Study:

• To develop a microfluidic strategy for efficient and rapid evaluation of switchable solvents in CO2-mediated liquid-liquid extraction.
• To enable high-throughput screening of switchable solvents and optimize extraction conditions.

Main Methods:

• A microfluidic platform was designed to study CO2-mediated solvent extraction using droplets of aqueous extractant and switchable solvent in a non-polar liquid.
• Gaseous CO2 was supplied to the microfluidic segment, inducing a phase transfer of the switchable solvent.
• Time-dependent droplet volume variations were monitored to determine extraction efficiency and kinetics.

Main Results:

• The microfluidic platform enabled time- and labor-efficient studies of CO2-mediated extraction.
• Accurate temporal characterization of the extraction process was achieved, reducing the required amount of switchable solvents.
• The platform demonstrated high-throughput screening capabilities for various nitrogenous bases.

Conclusions:

• The developed microfluidic strategy significantly enhances the evaluation and screening of switchable solvents for reactive liquid-liquid extraction.
• This approach accelerates the optimization of greener and more energy-efficient separation processes.