PVA/PVP blend polymer matrix for hosting carriers in facilitated transport membranes: Synergistic enhancement of CO2 separation performance

CO2 separation performance in facilitated transport membranes has been reported depended not only on the CO2 carrier properties but also to a great extent on the polymeric matrix regarding the capacity of retaining water and carriers as well as the processability for coating defect-free ultra-thin films. In this study, the blends of hydrophilic polymers polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) were studied to find an optimal polymer matrix to host carriers in facilitated transport membranes for enhanced CO2 separation. It is found out that the optimized blend is 50/50 PVA/PVP by weight, which shows a significant increase in the water uptake (from 63 to 84%) at equilibrium state compared to the neat PVA. Polyethyleneimine (PEI) was employed to provide sample carriers to evaluate the synergistic effect of PVA and PVP on the CO2 separation performance. A thin film composite (TFC) membrane of the optimized blend (50/50 PVA/PVP with 50 wt% PEI) was fabricated on polysulfone (PSf) porous support. The fabrication of the TFC membranes is simple and low cost, and CO2 permeance of the optimized blend membrane is nearly doubled with the CO2/N2 selectivity remained unchanged, showing great potential for industrial applications of the resulted membranes

A Brief Review of Nanocellulose Based Hybrid Membranes for CO2 Separation

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

A Brief Review of Nanocellulose Based Hybrid Membranes for CO₂ Separation

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

PVA/nanocellulose nanocomposite membranes for CO2 separation from flue gas

In this paper, we explore the use of nanocelluloses as an additive to poly (vinyl alcohol) (PVA) nanocomposite membranes for CO2/N2 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 CO2 permeance (127.8 ± 5.5 GPU) and increased CO2/N2 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 nanocellulose particles are important nanocellulose traits that improve membrane performance

Fabrication and Evaluation of Bio-based Nanocomposite TFC Hollow Fiber Membranes for Enhanced CO2 capture

Nanocellulose is a promising and sustainable biobased nanomaterial because of 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 (CNCs) and nanocellulose fibers (CNFs) were incorporated into polyvinyl alcohol (PVA) to prepare evenly dispersed nanocomposites. The resultant nanocomposite materials containing up to 80 wt % of nanocellulose were coated as defect-free, thin-film-composite selective layers onto hollow fiber membrane substrates via dip-coating for efficient CO2 capture. Thermogravimetric analysis, Fourier-transform infrared, X-ray diffraction, scanning transmission electron microscopy, scanning electron microscopy, 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 CO2 permeance and CO2/N2 selectivity compared to the PVA/CNF membranes and neat PVA membranes. The addition of CNCs showed more positive effects on the CO2 permeation compared to CNFs. Under optimized conditions, CO2 permeance of 672 GPU with a CO2/N2 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 1 year. The interface between the polymer phase and charged CNFs is believed to form fast gas transport channels at the humid state and thus enhances CO2 permeation

Nanocomposite membranes with high-charge and size-screened phosphorylated nanocellulose fibrils for CO2 separation

In this study, cellulose nanofibrils (CNF) of high charge (H-P-CNF) and screened size (H-P-CNF-S) were fabricated by increasing the charge of phosphorylated cellulose nanofibrils (P-CNFs) during the pre-treatment step of CNF production. Results show that the H-P-CNF have a significantly higher charge (3.41 mmol g−1) compared with P-CNF (1.86 mmol g−1). Centrifugation of H-P-CNF gave a supernatant with higher charge (5.4 mmol g−1) and a reduced size (H-P-CNF-S). These tailored nanocelluloses were added to polyvinyl alcohol (PVA) solutions and the suspensions were successfully coated on porous polysulfone (PSf) supports to produce thin-film nanocomposite membranes. The humid mixed gas permeation tests show that CO2 permeability increases for membranes with the addition of H-P-CNF-S by 52% and 160%, compared with the P-CNF/PVA membrane and neat PVA membrane, respectively