Computational study of the dissolution of cellulose into single chains: the role of the solvent and agitation

We investigate the dissolution mechanism of cellulose using molecular dynamics simulations in both water and a mixture solvent consisting of water with Na+, OH− and urea. As a first computational study of its kind, we apply periodic external forces that mimic agitation of the suspension. Without the agitation, the bundles do not dissolve, neither in water nor solvent. In the solvent mixture the bundle swells with significant amounts of urea entering the bundle, as well as more water than in the bundles subjected to pure water. We also find that the mixture solution stabilizes cellulose sheets, while in water these immediately collapse into bundles. Under agitation the bundles dissolve more easily in the solvent mixture than in water, where sheets of cellulose remain that are bound together through hydrophobic interactions. Our findings highlight the importance of urea in the solvent, as well as the hydrophobic interactions, and are consistent with experimental results

Computational study of the dissolution of cellulose into single chains: the role of the solvent and agitation

We investigate the dissolution mechanism of cellulose using molecular dynamics simulations in both water and a mixture solvent consisting of water with Na+, OH− and urea. As a first computational study of its kind, we apply periodic external forces that mimic agitation of the suspension. Without the agitation, the bundles do not dissolve, neither in water nor solvent. In the solvent mixture the bundle swells with significant amounts of urea entering the bundle, as well as more water than in the bundles subjected to pure water. We also find that the mixture solution stabilizes cellulose sheets, while in water these immediately collapse into bundles. Under agitation the bundles dissolve more easily in the solvent mixture than in water, where sheets of cellulose remain that are bound together through hydrophobic interactions. Our findings highlight the importance of urea in the solvent, as well as the hydrophobic interactions, and are consistent with experimental results

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

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