Biobased ionic liquid solutions for an efficient post-combustion CO2 capture system

Abstract

This study explores the use of ionic liquids (ILs) as a novel and efficient alternative to conventional monoethanolamine (MEA) for CO₂ capture. While MEA scrubbing is well-known for carbon sequestration, it faces limitations such as high energy consumption, toxicity, and rapid degradation. In contrast, ILs offer advantages such as non-volatility, stability, and reduced corrosiveness. We focus on a biodegradable IL comprising choline ([Cho]) and proline ([Pro]) amino acids to create an eco-friendly solution. Dimethyl sulfoxide (DMSO) is introduced as a diluent to mitigate viscosity issues during CO₂ uptake. Our research measures the thermo-physical properties, including density and viscosity of [Cho][Pro] in DMSO at different concentrations. The addition of DMSO resulted in a viscosity reduction of >97 % at a temperature of 303 K for the three virgin solutions compared to the pure IL. In addition, the CO₂ capture performance was evaluated using a system of absorption and desorption reactors. The results show that the 25 % wt [Cho][Pro] solution excels, achieving over 90 % CO₂ absorption, 0.66 $mo{l}_{C{O}_2}/mo{l}_{IL}$ in the first cycle, and demonstrating high reusability and regeneration efficiency over multiple cycles. Comparisons indicate that the IL solution outperforms traditional aqueous MEA solutions. Longer term testing confirms the solution's stability and minimal degradation, achieving a regeneration efficiency of >55 % over 30 cycles, suggesting the potential of [Cho][Pro] for sustainable long-term CO₂ capture applications.