The improvement of ionic liquids on CO2 capture with biphasic absorbents

Biphasic absorbents composed of tetraethylenepentamine, 1-ethylimidazole, and H2O (TEH) exhibit notable absorption rates and CO2 loads. However, troublesome precipitation forms in the enriched phase due to strong interactions among absorption products. To address this issue, six amino acid ionic liquids (AAILs) were introduced as split-phase regulators in TEH, developing a liquid–liquid biphasic absorption system TEH-AAILs, with outstanding absorption performance. By analyzing the kinetic data and establishing the evaluation parameters, combined with molecular dynamics simulations, the effects of AAILs on the loading and phasing performance were assessed. Remarkably, TEH-[Ser] was screened to possess good performance. Spectral analysis of the TEH-[Ser] reaction mechanism further elucidates the bridged hydrogen bonding structure between [Ser]–CO2 and H2O, highlighting its role in enhancing regeneration efficiency. This study provides insights into the design and optimization of biphasic absorbents for efficient CO2 capture.