Energy-Efficient Amine-Based Deep Eutectic Solvents for CO₂ Absorption

High energy consumption during aqueous solvent regeneration limits the development of industrial CO2 capture. To address this, a series of amine-based deep eutectic solvents (DESs) were designed and synthesized. Analysis using the Arrhenius equation showed a strong linear correlation between ln(η) and 1/T for DES viscosity. The optimal DES was identified as pyrazole (Pyr)/N-ethanolamine (EAE) at a 1:5 molar ratio. At 308.15 K and 1 bar, [Pyr][EAE] (1:5) exhibited an absorption capacity of 0.1962 gCO2/gDES, and the experimental data were consistent with the values predicted by the Avrami kinetic model. FTIR and DSC confirmed the DES structure and thermostability. Absorption enthalpy, calculated via the Van’t Hoff equation, was determined to be 67.52 kJ/mol. Regeneration energy consumption was calculated as 1.828 GJ/tCO2. Absorptive capacity remained stable over 10 absorption–desorption cycles, with FT-IR showing no significant changes in the recycled DES. Additionally, FT-IR and 13C NMR confirmed chemisorption through carbamate formation.