Chitosan/ZIF-8 Composite Beads Fabricated by In Situ Growth of MOFs Crystals on Chitosan Beads for CO2 Adsorption

摘要

CO2 responsive polymer chitosan is introduced to fabricate polymer/MOFs composite materials used to explore CO2 adsorption and recyclability. Chitosan beads (CBs) are successively immersed in the solution of Zn2+ and the solution of 2-methylimidazole to fabricate chitosan/ZIF-8 composite beads (CBsZx) by in situ growth of ZIF-8 crystal on chitosan beads. CBsZx are characterized by powder XRD, FT-IR, SEM, TEM, TGA and BET. The morphology, size and distribution of the ZIF-8 crystals on CBsZx are tuned by adjusting the concentration of Zn2+ in the soaking solution. The coordination of the free amino groups on chitosan skeleton with Zn2+ and self-emulsifying properties of chitosan have played a key role in situ growth of the ZIF-8 crystals on chitosan beads. Additionally, the adsorption capacity and recyclability of CBsZx for CO2 has been evaluated. Compared with the pure ZIF-8 crystals, the adsorption capacity of CBsZx for CO2 is significantly enhanced by 90 %. The kinetic models indicate that the adsorption of CBsZx for CO2 belongs to physical adsorption, when the ZIF-8 crystals on chitosan beads have the regular shape and size. Moreover, the adsorption capacity of CBsZx for CO2 is remained more than 80 % after 3 recycling.