A promising process to modify cellulose nanofibers for carbon dioxide (CO2) adsorption

[Display omitted] •Surface modification of CNF was performed using phthalimide.•Air nanofilter was made from modified CNF with high potentiality for CO2 adsorption.•Modified CNF had greater pores’ surface area with higher phthalimide fraction.•The CO2 adsorption was improved by increasing temperature, humidity and pressure.•The drop of pressure in all samples was less than the Department of Energy Standard. A novel process of using phthalimide to modify cellulose nanofibers (CNF) for CO2 adsorption was studied. The effectiveness of the modification was confirmed by ATR-IR. Phthalimide incorporation onto CNF was confirmed with the characteristic peaks of NH2, C–N, and ester bonding COO− was observable. The XPS analyses confirmed the presence of N1s peak in Ph-CNF, meaning that the hydroxyl groups reacted with the amino groups (NH2) of phthalimide on the CNF surface. Based on the results, surface modification and addition of phthalimide increased the specific surface area, but also decreased the overall porosity, size of pores and volume of pores. When the temperature, humidity, pressure, and airflow rate increased, the CO2 adsorption significantly increased. The CO2 adsorption of phthalimide-modified CNF was confirmed by ATR-IR spectroscopy as the characteristic peaks of HCO3−,NH3+ and ester bonding NCOO− were visible on the spectra.