Wei-Zheng Shen1,2, Kumakshi Sharma1,2 and Carlo Montemagno1,2.
1Ingenuity Lab, 11421 Saskatchewan Drive, Edmonton, Alberta T6G 2M9, Canada.
2Department of Chemical and Materials Engineering, University of Alberta, Edmonton T6G 2V4, Canada.
The reaction between aldehyde-functionalized cellulose nanocrystals (CNCs) and branched (Mw = 10K, 70K, 50-100K, and 250K) polyethyleneimine (PEI) yields the covalent crosslink of the nanocrystals to the polymer. The resulted PEI-functionalized CNCs form porous sponge via a freeze-drying process, which is able to quickly capture dry CO2 from air with a maximum CO2/amine efficiency of 0.18 (molar ratio) over a half-time of 1.5 min at 90 oC. Once the CO2 is captured, it can be safely stored inside the pores at room temperature for a month even in other gas atmosphere, such as N2 or air. Fast and complete desorption of CO2 is accomplished by heating under N2 at 90 oC with a half-time of 7.1 min. The capacity of CO2 capture is maintained even after five cycles of adsorption and desorption process. Most interestingly, after CO2 absorbing the sponge shows a photoluminescence at 470 nm excited by a UV light at 365 nm, which offers a quick and low-cost method to monitor if the CO2 uptake is reached its capacity. Besides, the quantity of CO2 absorbed is systematically studied on the impact of temperature, the molecular weight of the PEI, and surface area of the sponge. This lightweight reusable absorption material offers a potential solution for CO2 sequestration in closed systems such as spacecraft, orbiting space stations and submarines, and so forth.