Ultrasound-assisted Desorption of CO2 from Carbon Dioxide Binding Organic Liquids

CO2 absorption/desorption performance of 2-tert-Butyl-1,1,3,3-tetramethylguanidine (BTMG) and 1-Hexanol blend, which is a novel carbon dioxide binding organic liquid (CO2BOL) system, was studied in order to investigate the behavior of ultrasound-assisted desorption. Pure CO2 was first absorbed into a 10 wt percent BTMG solution in a semi-batch stirred reactor at 303 K and at 2 atm until equilibrium was reached, followed by ultrasound-assisted desorption at 353 K under nitrogen atmosphere. Experiments were repeated in the absence of ultrasound, keeping everything else the same. The CO2 loading of BTMG:1-Hexanol solvent system was found to be a very favourable ratio of 1.05 mol CO2/mol BTMG. When compared with conventional desorption, ultrasound-assisted desorption resulted in enhanced desorption rate so that the solvent regeneration time was significantly shortened. Enhancement of desorption rate was most significant/vigorous at the initial stages of desorption process. Further, regeneration of this CO2BOL was possible at 353 K without any phase change. Experimental results clearly show that the ultrasound-assisted desorption is an effective process intensification tool leading to significantly minimised energy consumption for regeneration. To ensure effectiveness of regeneration, reversibility of the solvent system was also investigated by using Fourier transform infrared spectrometry.