Preferential heating of aqueous amine solutions using infrared radiation at selected vibrational frequencies: A...

A recent CO₂ capture experiment suggests that microwaves might be beneficial for regeneration of aqueous amine solutions due to both thermal and nonthermal effects [S. J. McGurk et al., Appl. Energy 192, 126 (2017)]. We use classical molecular dynamics to simulate heating of aqueous amine solutions using electromagnetic radiation with different frequencies in both microwave and infrared regions. The infrared frequencies were selected based on the partial vibrational density of states of water and amine. Unlike the microwave case, we found that preferential heating of water or amine can be achieved using their relevant vibrational frequencies in the infrared region, suggesting that microwave heating is not an optimal choice for an efficient amine regeneration reported in a recent carbon capture experiment. Interestingly, only flexible water models augmented with an anharmonic O-H bond stretching potential were able to quantitatively predict the expected differential heating profiles of systems involving water.