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

Abstract

BACKGROUNDThe 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.RESULTSIn 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.CONCLUSIONThe 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).