High-frequency (470 kHz) ultrasonics-assisted room temperature CO2 stripping and fate of Sono exposed solvent

BACKGROUND

The conventional CO₂ stripping process in solvent-based postcombustion CO₂ capture (PCCC) process uses heating to strip the CO₂ (~120 °C). However, the challenges associated with this method are high energy consumption in degassing the CO₂ from solvent, solvent loss and degradation resulting from the high –temperatures, resulting in high energy consumption typical of solvent-based PCCC. The present study demonstrates the use of bath-type sonication (470 kHz frequency) to remove CO₂ from CO₂ loaded 30 wt% Monoethanolamine under controlled temperature conditions. Solvent performance was evaluated following exposure to 2 h conventional heating and 75 h sonication.

RESULTS

In a batch sono-assisted process, CO₂ stripping became possible at 17.5 °C compared to 102.2 °C using the conventional method. Increasing the sonication time led decreased carbon loading and increased stripping efficiency. The stripping rate was high at the initial stages of treatment. Evaluation of sono-exposed solvents exhibited decreased pH during CO₂ loading and decreased absorption capacity of the conventionally heated sample.

CONCLUSION

The sono-assisted method consumes 3.57-foldless energy than conventional heating. Its CO₂ stripping rate was found to be higher within 5 min of sonication. Notably, the maximum temperature reached for the 1 h intervening mode of sonication at 470 kHz was 49.49 °C. The reduction in absorption capacity per hour of conventional heating was 24.5%, whereas for sonication it was <0.4% and solvent loss was 19.7% lower than conventional. There was no significant change in the color, pH and density of the sample. A 20.4% higher surface tension than that of the virgin sample was observed. © 2024 Society of Chemical Industry (SCI).