Nanocellulose is a promising and sustainable bio-based nanomaterial due to its excellent mechanical properties, biocompatibility, natural abundance, and especially its high aspect ratio.Interest in applying nanocellulose as nanofillers in membrane fabrication has been growing rapidly in recent years. In the present work, nanocellulose crystals (CNC) and nanocellulose fibers (CNF) were incorporated into polyvinyl alcohol (PVA) to prepare evenly dispersed nanocomposite. The resultant nanocomposite materials containing up to 80 wt% of nanocellulose were coated as defectfree, thin-film-composite (TFC) selective layers onto hollow fiber membrane substrates via dipcoating for efficient CO 2 capture. TGA, FTIR, XRD, STEM, SEM, and humid mixed gas permeation test were used to evaluate the nanocomposite materials and the membranes. The resultant PVA/CNC nanocomposite membranes exhibit both higher CO 2 permeance and CO 2 /N 2 selectivity compared to the PVA/CNF membranes and the neat PVA membranes. The addition of CNC showed more positive effects on the CO 2 permeation compared to CNF. Under optimized conditions, CO 2 permeance of 672 GPU with a CO 2 /N 2 selectivity of 43.6 was obtained with a PVA/CNC membrane. Excellent long-term stability of the membrane was also documented within a period of up to one year. The interface between the polymer phase and the charged nanocellulose fibers is believed to form fast gas transport channels at humid state and thus enhances CO 2 permeation. industrial interests, and the materials used are sustainable, low cost and easy to process. This work may open a new window for the utilization of bio-based materials from nature for the fabrication of CO 2 separation membranes.

Due to the high specific surface area, high mechanical strength and broad possibility of surface modification, nanocellulose has obtained much attention as a new class of bio-based nanomaterials with promising potential in a wide variety of applications. Recently, a considerable amount of research has been aimed to the fabrication of nanocellulose based hybrid membranes for water treatment. However, nanocellulose based hybrid gas separation membrane is still a new research area. Herein, we force on recent advancements in the fabrication methods and separation performances of nanocellulose-based hybrid membranes for CO2 separation, the transport mechanisms involved, along with the challenges in the utilization of nanocellulose in membranes. Finally, some perspectives on future R&D of nanocellulose-based membranes for CO2 separation are proposed.

In this paper, we explore the use of nanocelluloses as an additive to poly (vinyl alcohol) (PVA) nanocomposite membranes for CO 2 /N 2 mixed-gas separation. Our findings are that several types of nanocellulose can be used to improve membrane performance. PVA/cellulose nanocrystals (CNC) nanocomposite membranes have the most promising performance, with increased CO 2 permeance (127.8 ± 5.5 GPU) and increased CO 2 /N 2 separation factor (39 ± 0.4) compared to PVA composite membranes, with permeance 105.5 ± 1.9 GPU and separation factor 36 ± 0.5. The performance of PVA/CNC membranes is similar compared to PVA/carbon nanotubes (CNTs) membranes shown earlier. Thus, CNTs can be replaced by CNC that is biodegradable and non-toxic. Investigating several different nanocellulose types reveal that a high nanocellulose charge and small nano-cellulose particles are important nanocellulose traits that improve membrane performance.

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