In-depth characterization of choline lysinate ([Cho][Lys]) in ethylene glycol for optimized CO₂ capture conditions

Choline Lysinate, an amino acid ionic liquid, demonstrates significant potential as an environmentally friendly solvent for post-combustion CO₂ capture. This study explores the physicochemical properties and CO₂ absorption performance of Choline Lysinate in ethylene glycol solutions at concentrations of 25 %, 33 %, and 50 % by weight. Key findings indicate that while the 50 % solution offers the highest CO₂ capacity, its tendency to form precipitates post-absorption renders it impractical for industrial use. The 33 % solution achieved optimal performance with a CO₂ absorption capacity of 4.45 % by weight, maintaining structural stability and thermal resistance under aging conditions. ATR-IR and TGA analyses confirmed carbamate formation during CO₂ capture and demonstrated the thermal stability of the solutions. The 25 % solution exhibited viscosity 1.3 times lower than the 33 % solution and 2.5 times lower than the 50 % solution at 30 °C, resulting in significantly reduced energy demands for solvent circulation and regeneration. Despite slightly lower CO₂ absorption (3.83 % by weight), the 25 % solution demonstrated superior energy efficiency, making it the ideal ionic liquid concentration for scalable industrial applications. These findings underscore the potential of Choline Lysinate -based solutions for sustainable CO₂ capture, offering a balance of efficiency and process stability.