Enhancing CO2 desorption in MEA solvent using low-frequency ultrasound: A flow-through reactor study

• Our study highlights the significant energy savings achieved through the application of low-frequency ultrasound in the CO 2 desorption process using a 30 wt. % monoethanolamine (MEA) solvent.Our findings demonstrate that ultrasound not only accelerates the desorption process but also substantially reduces the energy required (50 %) to release CO 2 . Specifically, the energy consumption for ultrasound-assisted desorption is 172.65 kJ mol -1 CO 2 , compared to 343.85 kJ mol -1 CO 2 for conventional heating methods. This represents a remarkable reduction in energy usage, making the process more efficient and cost-effective. • The use of ultrasound enhances heat and mass transfer through acoustic streaming and cavitation, leading to faster desorption times. Additionally, the flow-through reactor system used in our experiments suggests that these energy savings can be scaled up for larger-scale processing. • At higher desorption temperatures, sonication at 80 °C and above reduces CO 2 loading in MEA below its thermodynamic equilibrium by 16 %, allowing CO 2 release at 100 °C instead of 120 °C with heating alone. This two-peak CO 2 release pattern—initially from thermolysis and later from enhanced mass transfer—highlights the benefits of acoustic effects such as microstreams, vortices, and rectified diffusion. Moreover, this method may mitigate solvent degradation at high temperatures, further contributing to energy efficiency. • Our study underscores the potential of ultrasound technology to significantly decrease energy consumption in CO 2 desorption processes, thereby reducing operational costs for carbon capture facilities. We believe that our findings offer valuable insights into developing more sustainable and economical carbon capture technologies . This study explores the efficacy of ultrasound (US)-assisted CO 2 desorption in a 30 wt. % monoethanolamine (MEA) solvent using a flow-through reactor. The tests demonstrated that the application of low-frequency (20 kHz) ultrasound accelerates the desorption process and reduces the desorption time required to release the same amount of CO 2 for a given solvent compared to desorption by only heating the sample. This acceleration is attributed to the direct energy input into the solvent as well as the enhancement of heat and mass transfer caused by acoustic streaming and acoustic cavitation. The use of flow-through reactor systems suggests that the results can be scaled up to larger-scale processing. Notable improvements were observed at higher desorption temperatures, with sonication at 80 °C and above reducing CO 2 loading in MEA below its thermodynamic equilibrium by 16 %. This allows CO 2 release at 100 °C, compared to 120 °C with heating alone. The two-peak CO 2 release pattern under sonication — initially from thermolysis and later from enhanced mass transfer — highlights the benefits of acoustic effects such as microstreams, vortices, and rectified diffusion. This method may also mitigate solvent degradation at high temperatures. Compared to conventional heating, applying sonication in a 30 wt. % MEA solvent consumes much less energy (172.65 kJ/mol CO 2 compared to 343.85 kJ/mol CO 2 ) to release the same amount of CO 2 at similar desorption temperatures. This demonstrates that the application of low-frequency ultrasound can significantly decrease energy consumption during CO 2 desorption. This method may result in decreased operational costs, provided affordable power is accessible for carbon capture facilities, especially via US-assisted desorption.