Pine needles derived nanocellulose/ionic liquid-modified ZIF-8 composite beads for CO2 adsorption

To develop an environmentally friendly CO 2 capture technology, composite adsorbent beads were synthesized through the in situ growth of ZIF-8 in a nanocellulose gel scaffold prepared from pine needles-derived cellulose. The composite beads were subsequently functionalized with three ionic liquids ([BMIM][PF 6 ], [BMIM][BF 4 ], and [EMIM][TF 2 N]), which induced partial dissolution of the nanocellulose. This process resulted in the formation of unique wrinkled microstructures, resembling rice grains in morphology but exhibiting higher compressive strength. Notably, the IL-loaded CNF/ILs@ZIF-8 composites exhibited significantly superior adsorption performance over unmodified CNF@ZIF-8 (CZ) beads. Under static conditions (3 bar, 273 K), all three functionalized CNF/ILs@ZIF-8 variants enhanced CO 2 uptake capacities by > 46 %, with the [BMIM][PF 6 ] modified beads retaining 85.36 % of initial adsorption capacity after six adsorption–desorption cycles. Furthermore, under competitive dynamic adsorption (1 bar, 273 K), the [BMIM][BF 4 ] modified beads achieved a 43.12 % enhancement in CO 2 /N 2 selectivity compared to CZ. This work provides a MOF granulation strategy with process safety and environmental sustainability, potentially extending MOF applications in gas adsorption technologies.