Enhancement of the rate of desorption of CO2 through Ultrasound and Mechanical agitation

This work explores ultrasound and mechanical stirring as process intensification strategies to enhance CO2 desorption from Monoethanolamine (MEA)-based solvents under atmospheric conditions. Batch experiments assessed the influence of ultrasound intensity, stirring speed (500–1000 rpm), temperature (60–80 °C), MEA concentration (10 and 30 wt%), and vapour reduction additives (VRAs). The presence of a CO₂ saturated solution proved to be critical for the effectiveness of any agitation technique. For 30 wt% MEA at 80° C, ultrasound (at all tested intensities) accelerated the rate of desorption seven-fold within five minutes, reducing loading from 0.60 to 0.50 mol CO₂/mol MEA compared to undisturbed heating at the same temperature. Mechanical stirring at 1000 rpm achieved a nine-fold rate increase. At lower driving forces (10 wt% MEA), improvements were negligible, confirming equilibrium constraints. The addition of Monoethylene glycol and Urea as VRAs increased viscosity and reduced ultrasonic efficiency, whereas stirring remained effective. Both techniques were most impactful in bubbling regimes, enabling a rapid approach to equilibrium and indicating potential for reduced residence time and energy demand in industrial CO₂ capture systems.