Quantitative Study on Fast Kinetics of Hydrodynamic Liquid Absorption of CO₂ Microbubbles Enabled by Microfluidic...

Area of Science:

• Chemical Engineering
• Environmental Science
• Fluid Dynamics

Background:

• Liquid absorption is a key carbon capture method for global warming mitigation.
• Mass transfer kinetics at the gas-liquid interface are crucial for absorption efficiency.
• Understanding factors like absorbent type and bubble dynamics is vital for optimizing CO2 capture.

Purpose of the Study:

• To quantitatively investigate the fast kinetics of hydrodynamic liquid absorption of carbon dioxide (CO2) microbubbles.
• To analyze the impact of absorbent type and concentration on CO2 microbubble absorption.
• To elucidate the mass transfer mechanisms governing CO2 absorption in microfluidic systems.

Main Methods:

• Utilized a microfluidic platform with flow-focused channels to generate CO2 microbubbles in aqueous solutions.
• Employed three absorbents: isophorone diamine (IPDA), monoethanolamine (MEA), and potassium hydroxide (KOH).
• Visualized bubble dynamics using high-speed microscopy and analyzed morphology and velocity; performed computational fluid dynamics (CFD) analysis.

Main Results:

• CO2 bubble size rapidly decreased within 100 ms, reaching equilibrium.
• Achieved up to 99% volume shrinkage and mass loss within 200 ms.
• Absorption efficiency correlated positively with absorbent volume fraction up to 20%; CFD revealed convection dominates mass transfer (Peclet number: 25,000–42,500).

Conclusions:

• Engineered microbubbles flowing in liquid solutions significantly enhance interphase mass transfer for CO2 capture.
• Hydrodynamic effects, particularly convection, play a dominant role in accelerating CO2 dissolution.
• This approach offers a promising strategy for efficient and rapid carbon capture technologies.