New cellulose based ionic compounds as low-cost sorbents for CO2 capture

• Ionic compounds were obtained from cellulose modification with citric acid and ionic liquids.
• Simulation and experimental results are in agreement about CO2 capture.
• Carboxylate groups are mainly responsible for the CO2 capture.
• The cation stabilizes the compounds keeping the anion CO2 binding sites non-occupied.

Supporting ionic liquids in solid materials is a promising solution to address CO2 capture. Cellulose is a versatile and low-cost material. The support of different ionic liquids cations on cellulose extracted from rice husk is an excellent strategy for CO2 capture. This study reports chemical modification of cellulose fibers extracted from rice husk with different ionic liquids cations and its potential for CO2 capture. The obtained ionic compounds were characterized by FTIR, XRD, FESEM, TGA and BET. CO2 sorption capacity was gravimetrically assessed in a Magnetic Suspension Balance (MSB). In addition, ab Initio calculations were performed. First, the carboxylate groups are responsible for the CO2 capture process. Second, the cation maintains the CO2 binding sites of the anion partially or fully non-occupied, improving the CO2-ionic compound affinity. The best result for CO2 sorption was obtained for the ionic compound CL-TBA of 71 mgCO2/g at 3 MPa and 25 °C. At lower pressures, this compound presents a high CO2 sorption value (44 mgCO2/g at 0.1 MPa). We conclude that these ionic compounds deserve further attention in the post-combustion process.