Synthesis and Characterization of Amino Acid-Based Ionic Liquids for Selective Absorption of CO2 Using Liquid Foam Bed and Semi-Batch Reactors

Abstract

Carbon dioxide (CO₂) gas emissions were produced by burning fossil fuels for power generation, automobiles, and other major industrial processes. Hence, there is a need for the absorption of CO₂ and convert it into useful hydrocarbons using carbon capture and storage technologies. This work emphasizes the synthesis and characterization of amino acid-based ionic liquids (AAILs) for CO₂ absorption via a liquid foam bed reactor (FBR) and semi-batch equilibrium studies (SBES). Seven different AAILs namely [TETA][ALA], [TETA][LYS], [TETA][GLU], [TETA][GLN], [TETA][MET], and [TETA][PHE] were newly synthesized. The AAILs were characterized using FTIR and Raman spectroscopy, ¹H, and ¹³C NMR spectroscopy to confirm the AAILs. The physical properties such as viscosity, density, and surface tension of AAILs were also presented. The highest and lowest densities of 1.170 and 1.0646 g cm^-3 were observed for [TETA][ASP] and [TETA][ALA] respectively among synthesized AAILs. The application of AAILs in FBR and SBES for the absorption of CO₂ was performed under different experimental conditions. Parameters such as the effect of initial concentration, effect of surfactant, and pH, as well as regeneration of AAILs, were studied. [TETA][LYS] gave the highest moles of CO₂ absorbed per mole of [TETA][LYS] used, it is reported that the highest mole ratio of 0.442, 0.172, and 0.112, was observed in the initial concentration of 500, 300 and 100 mil respectively. Finally, it was noted that the highest mole ratio of CO₂ per mole of [TETA][GLU] was obtained at 0.166, followed by 0.133 for [TETA][ALA] during desorption studies.