Cellulose最新文献

Natural fibre composites, rich in cellulose, are cheaper and greener than synthetic composites, increasing their appeal. However, these composites often exhibit poor mechanical and interfacial characteristics. To enhance interfacial bonding and mechanical properties, we coat natural flax fibres, which have a high cellulose content, with reduced graphene oxide (rGO). Graphene-based nanomaterials improved interfacial shear strength by 184.94% and tensile strength by 81.14% in untreated flax fibres. The enhancement is attributed to the improved mechanical interlocking between the cellulose-rich fibres and graphene-based flakes, along with the roughening of the fibre surface. Field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) examined the structure and morphology of rGO-coated fibres. The findings were further quantified using Thermogravimetric Analysis (TGA). A water absorption study revealed that the rGO coating enhanced the moisture resistance of the cellulose-based flax fibres. Untreated flax/epoxy composites exhibited 13.7 and 64% lower tensile and flexural strengths, respectively, compared to rGO-modified composites. Moreover, composites reinforced with 1 wt% rGO-coated cellulose-rich fibres showed a 44% reduction in moisture diffusion. The results suggest that eco-friendly, coated cellulose-based flax fibre composites could serve as sustainable alternatives to synthetic fibre composites in industrial applications.

Functionalized cellulose nanofibril membranes have emerged as promising candidates for their use as electrolytes in proton exchange membrane fuel cells (PEMFCs). However, knowledge on this application is still limited, and topics like the effect of the chemical characteristics of the nanomaterial and their possible interaction with additives and crosslinkers have remained unclear. For this reason, this study focuses on investigating the influence of lignin in the nanomaterial, the type of functionalization of the nanofibrils, and the use of Kymene™ as a crosslinker, on the physicochemical and transport properties of membranes, as well as their performance in a laboratory PEMFC. For this, sulfated lignocellulose nanofibrils (LCNF–OSO₃⁻), sulfonated lignocellulose nanofibrils (LCNF–SO₃⁻), and sulfated cellulose nanofibrils (CNF–OSO₃⁻) were produced and used to fabricate membranes via solvent casting. Additionally, Kymene™ resin was added. The characterization of nanomaterials showed that lignin hinders the sulfation of nanofibrils and the cleavage of cellulose. The type of functionalization affected the fibril-Kymene™ reactivity in the membranes. On the one hand, the LCNF–SO₃⁻ primarily interacted with Kymene™ via hydrogen bonds, which enhanced the water absorption capacity and swelling ratio of the membrane. On the other hand, the sulfated nanofibrils exhibited the highest reactivity with Kymene™, linked mostly via covalent bonds. Finally, the LCNF–OSO₃⁻ membranes crosslinked with Kymene™ exhibited superior proton conductivity (4.3 mS/cm at 40 °C) and performance in laboratory PEMFC (2.87 mW/cm² at 23 °C), showing that lignin-containing nanofibrils and sulfate groups enhance the membrane properties for its application as an electrolyte.

To achieve sustainable development of resources and reduce environmental pollution, it is particularly important to accelerate the use of renewable resources. Cellulose is an abundant renewable resource with biocompatible, degradable and recyclable characteristics. To further improve the effect on cellulose, 1-butyl-3-methylimidazole chloride ([Bmim]Cl)/dimethyl sulfoxide (DMSO) was used to dissolve and recover cellulose from waste cotton. Regenerated cellulose (RCF) and regenerated cellulose-polyvinyl alcohol blend (RCF/PVA) were prepared by wet spinning. To study the dyeing performance of Pu ’er tea pigment on RCF/PVA The dyeing performance of RCF/PVA was investigated. The dyeing performance of RCF/PVA was investigated. The experiments showed that, compared with RCF, the strength of RCF/PVA with 15% PVA was improved, and the residual carbon at 700 °C of thermal decomposition was reduced from 21.4 to 0.1%. With the increase of PVA content, RCF/PVA has better dyeing effect than pure cellulose regenerated fibre on the natural pigment extracted from Pu-erh tea, and the preparation of RCF/PVA provides a new way of researching new composite fibre materials.

Extensive use of synthetic polymeric membranes for separating immiscible liquids is concerned with a significant drawback that their interaction with organic solvents can lead to deterioration of membrane and contamination of organic phase. Repeated exposure to solvents can cause the polymeric matrix to break down, compromising membrane integrity and potentially releasing harmful contaminants into the desired phase. This not only affects the efficacy of the separation process but also raises environmental and toxicity concerns. We fabricated a chitosan-layered cotton (cellulose) fabric as a renewable, eco-friendly separator for organic/aqueous phase extraction. The tunable surface chemistry of cotton and chitosan may provide an opportunity for efficient separation of said phases under diverse physicochemical conditions. Infrared spectroscopic analysis indicated effective molecular interactions occured in the precursors during samples preparation. The treated cotton fabric showed good porosity, water uptake, permeability, tensile and thermal properties. When used for phase separation, single-layer coated cotton fabric (with chitosan, 1.5%, w/w) could separate ≥ 98% (v/v) n-hexane from the n-hexane/water (50/50, v/v) mixture in a controlled chamber at 25 °C, 1 atm, and 65% RH. In the n-hexane/water system with a surfactant, the n-hexane separation efficiency was limited to ~ 91% (v/v). Thereby, the chitosan-coated cotton matrix may be employed for organic/aqueous phase separations.

The term nanocellulose includes a group of cellulose-based nanofibers that have attracted great attention within the research community. To date, many different types of nanocelluloses are known with a range of dimensions and surface functionalities affecting the properties of the material and which applications they can be used for. One type of nanocellulose can be made through simultaneous esterification and hydrolysis of cellulose with oxalic acid. The reaction of cellulose with oxalic acid results in a cellulose ester (cellulose oxalate), that has a carboxylic acid attached through an ester bond. In this study, the stability of the cellulose oxalate ester towards base-catalysed hydrolysis was investigated through immersion in buffer solutions with pH ranging from 6 to 10. The results show that the ester is rapidly hydrolysed already within 24 h at pH above 8. It could also be concluded that the carboxylic acid functionality of the cellulose oxalate is relatively acidic (pKa of 3.8) and that for carboxylic group content determination through conductometric titration, the equivalence point and not the plateau should be used. The results from this study show that stability of the ester needs to be carefully considered when working with cellulose oxalate.

Deep eutectic solvents (DESs) are promising media for cellulose fiber (CF) modifications, such as swelling, dissolution, functionalization, and disintegration, owing to their low toxicity, biodegradability, and versatility. These modifications are governed by CF–DES interactions, regulated by the chemical structures of DES constituents. Here, nuclear magnetic resonance (NMR) spectroscopy was used to investigate the molecular interactions and dynamics between CFs and two isomeric non-derivatizing DESs comprising triethylmethylammonium chloride (TEMACl) with imidazole (Imi), TEMACl–Imi, or TEMACl with pyrazole (Pyra), TEMACl–Pyra. The NMR approach encompassed variable-temperature ¹H diffusion, T₁-and-T₂-relaxation, and ¹³C NMR experiments. Significant CF swelling occurred in TEMACl–Imi, highlighted by reduced Imi and almost unchanged TEMACl relaxation times. This indicated that Imi primarily accounted for the interaction with cellulose. Correspondingly, the diffusion coefficients (D) of both DES components reduced, probably because of the increased viscosity due to CF swelling, as well as restricted diffusion inside the swollen CFs. Further, the ¹³C NMR spectra displayed characteristic cellulose-backbone signals, indicating a swelling-induced increase in CF mobility. Conversely, TEMACl–Pyra exhibited significantly suppressed changes in ¹H-relaxation times and D, and no cellulose signal appeared in its ¹³C spectra. This indicated suppressed CF swelling and CF–DES interaction. The more significant CF swelling in TEMACl–Imi might stem from the formation of stronger hydrogen bonds by Imi with the hydroxyl groups in cellulose compared with those formed by Pyra. Overall, these findings highlight how the molecular configuration of DES facilitates cellulose interactions and the profound impact of these interactions on CF modification.

This study investigates the swelling and liquid retention properties of cellulosic pulp from cotton waste, cotton linters and conventional dissolving wood pulp in both neutral (water) and alkaline (sodium hydroxide) conditions in regard to the first phase of the viscose process (mercerization). The swelling of single fibers is investigated by microscopic observation of the diameter increase during immersion in the liquids, which resulted in a logarithmic trend over time. The retention properties are investigated by water and lye retention values, and the latter was coupled to the pressability of mercerized pulp through observation of the trend in press factor with increasing pressing times. The different materials behaved similarly in neutral conditions regarding single fiber swelling and retention properties. Alkaline conditions, on the other hand, resulted in increased swelling and retention properties for all materials compared to neutral conditions, and the cotton-based pulps showed higher single fiber swelling and retention of lye, accompanied by impeded pressability. Thereafter, several material properties were investigated; morphological fiber properties (fiber width, cell wall thickness and fiber coarseness), fines content, carbohydrate monomer composition, and charge density. The results indicate that a thin cell wall and large lumen of the cotton waste fibers affect their higher swelling and retention properties, but further investigation of other morphological, chemical and physical properties of the fibers and fiber networks in pulp sheets is necessary. However, these insights on the behavior of different pulps can already help industries with the optimization of implementation of cotton waste pulps for viscose production.

In recent years, nanocellulose has emerged as an ideal raw material for aerogel preparation because of its abundant availability, cost-effectiveness, and excellent biodegradability. Importantly, nanocellulose aerogels fabricated by physical or chemical methods exhibit unique three-dimensional network structures, high porosity (silimar to 99%), high specific surface areas (100-300m²/g), low densities (1-500mg/cm³), and exceptional adsorption properties. Additionally, the outstanding sustainability, biocompatibility, and degradability exhibited by such materials have attracted widespread attention from the viewpoint of environmental protection. In this review, the preparation techniques for nanocellulose aerogels are systematically summarized, with a particular focus on their adsorption mechanisms and performances. The preparation process is divided into four main steps: the preparation of nanocellulose, gelation of nanocellulose, solvent replacement of nanocellulose wet gel, and drying of nanocellulose wet aerogel. Furthermore, recent research progress in the field of nanocellulose aerogels for dye adsorption, oil–water separation, heavy metal ion adsorption, carbon dioxide adsorption and antibiotics and microplastics is comprehensively elaborated to provide theoretical references for the application of nanocellulose aerogels in the field of environmental pollution control.

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Here, a catalyst-free route is reported for fabricating self-standing and robust paper-based adsorbents for methylene blue (MB) removal from aqueous solutions through the attachment of montmorillonite (MMT) to filter paper (FP) substrate surfaces using polydimethylsiloxane (PDMS) chains. Characterization results showed that the thickness of the combined PDMS and MMT layer was 4.0 ± 0.7 g m⁻², with MMT accounting for 2.2 ± 0.3 wt% of the composite. The specific surface area of MMT, FP, and PDMS/MMT/FP composite was 203.4, 1.3, and 1.8 m² g⁻¹, respectively. A point of zero charge of 3.84 was measured for PDMS/MMT/FP. Spectroscopic analysis suggested interactions among MMT, PDMS, and FP, including the possible formation of Si–O–C bonds between PDMS and cellulose, the principal component of FP. Scanning electron microscopy (SEM) images revealed clay particles distributed uniformly across the fibers. MB adsorption tests conducted under identical conditions (100 mL, 5 mg L⁻¹; 6 cm × 6 cm sheets) showed that the PDMS/MMT/FP composite removed 90.0% of the dye (corresponding to a q_e of 1.4 mg g⁻¹), almost doubling the 51.3% removal performance of pristine FP, despite the low MMT loading of only 2.2 wt% in the composite. The PDMS/MMT/FP composite closely followed the pseudo‑second‑order kinetic model and showed a better fit to the Langmuir isotherm. Even after 15 days of continuous shaking in MB solution at 150 rpm, the PDMS/MMT/FP composite retained its integrity, still exhibiting MMT particles across its surface and similar Al contents before and after the MB adsorption test, as evidenced by SEM and spectroscopic studies. These findings demonstrate that our simple and environmentally benign route can produce low-cost, self-standing paper-based adsorbents with clear promise for wastewater-treatment applications.

The sustainable development of high-quality fibers from agricultural waste biomass offers a promising pathway for next-generation fiber-based food packaging and composite products. This study evaluates fiber production from hemp biomass using environmentally friendly approaches, including chemical-free autohydrolysis (AH), soda (alkaline) pulping (AL), and mild kraft pulping (HK), followed by peroxide and elemental chlorine-free (ECF) bleaching. Both bench-scale experiments and a pilot-scale soda pulping trial were conducted to evaluate the industrial scalability and feasibility of converting low-value agricultural residues, specifically hemp hurds, into high-quality fibers. Among the pulping methods, autohydrolysis resulted in the highest fiber yield, followed by lab-scale soda pulping, pilot-scale soda pulping, and mild kraft pulping. However, autohydrolysis exhibited limited delignification, as indicated by a high kappa and low pulp viscosity. In contrast, mild kraft pulping produced the lowest fiber yield but achieved higher fiber quality due to increased delignification. Following ECF bleaching, the kraft pulp (HKC) showed the highest brightness, lowest residual lignin content, and highest viscosity, indicating well-preserved cellulose integrity. AL and HK fibers exhibited lower coarseness and fines content, along with enhanced crystallinity and improved fiber morphology. Peroxide- and ECF-bleached AH fibers showed the highest anionic charge and carboxyl content, indicating strong potential for further chemical modification. While AH fibers are more suitable for molded and hygiene products, HK and AL fibers show greater potential for fiber-based food packaging and composite applications, contributing to the development of a circular bioeconomy.

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