Enhanced CO2 capture performance using deep eutectic solvent-immobilized silica slurry

• Incorporation of immobilized silica improved the CO 2 capture capacity of DES. • Desorption was achieved at a low temperature (90 °C) and a short time (25 min). • CO 2 sorption/desorption rates were improved by adding immobilized silica. • Thermal stability was enhanced by adding immobilized silica. • The slurry maintained the performance against long-term storage. • Silica with larger pores/surface area improved slurry performance more effectively. Efficient and reversible capture of CO 2 remains a critical challenge in advancing carbon capture technologies. In this study, a deep eutectic solvent (DES) comprising 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and ethylene glycol (EG) in a (1:2) molar ratio was selected as a CO 2 absorbent due to its high capture capacity, thermal stability, and ease of synthesis. To further enhance sorption/desorption performance, a range of slurries were developed by integrating the pure DES with silica particles impregnated with the same DES, introducing additional active sites for CO 2 capture. Results confirmed that adding 3 wt.% immobilized silica to the DES increased the CO 2 capture capacity from 16.77 wt.% for the pure DES to 20.23 wt.% for the slurry at 22°C and 1 bar. Moreover, the sorption rate increased from 0.41 mol-CO 2 /(kg-sorbent·min) for the pure DES to 0.51 mol-CO 2 /(kg-sorbent·min) for the slurry at 22°C, while the desorption rate increased from 0.63 mol-CO 2 /(kg-sorbent·min) at 90°C to 0.84 mol-CO 2 /(kg-sorbent·min). Also, the slurry exhibited promising capture capacity over consecutive sorption-desorption cycles (97.27 wt.%), minimal solvent loss against heating at 100 °C for 120 hr (0.64 wt.%), and stability against long-term storage up to one month.