Rapid and massive fractionation of hemicelluloses for purifying cellulose at room temperature by tetramethylammonium hydroxide

High-performance cellulose/thermoplastic polyurethane composites enabled by interaction-modulated cellulose regeneration

Strong interfacial adhesion between cellulose and other polymers is critical to achieve the properties required for specific applications in composite materials. Here, we developed a method for the simultaneous homogeneous dissolution of cellulose and thermoplastic polyurethane (TPU) in 1,8-diazabicyclo (5.4.0) undec-7-ene levulinate/dimethyl sulfoxide ([DBUH]Lev/DMSO) solvent. This process is essential for preparing cellulose/TPU composite films and fibers through interaction-modulated cellulose regeneration. Both cellulose and TPU can be easily dissolved together in [DBUH]Lev/DMSO solvent under mild conditions. The resulting cellulose/TPU solutions exhibited strong temperature sensitivity, shear-thinning behavior and viscoelasticity, making them suitable for cast films and continuous spinning. More importantly, research findings, including density functional theory calculations and experimental characterization, confirmed the high compatibility and interaction modulability of cellulose and TPU in the composite films. The representative C90T10 sample (cellulose/TPU, 90/10) showed high transparency (90 % at 800 nm) and excellent mechanical properties (tensile strength: 176 MPa; elongation at break: 8.1 %). Additionally, the maximum tensile strength and elongation at the break of the composite fiber from C90T10 were 214 MPa and 48.1 %, respectively. This method may provide a feasible approach to design and produce homogeneous environmentally friendly composites of cellulose and other polymers at the molecular level.

Advancing bamboo fiber reinforcement: A novel approach using eco-friendly plant ash alkali treatment

This study aimed to enhance the engineering performance of bamboo fibers for use in composite materials by employing a sustainable plant ash alkali treatment. The primary objective was to improve the tensile strength, crystallinity, and thermal stability of bamboo fibers, which are known for their high specific strength, low density, and biodegradability but suffer from poor compatibility with hydrophobic matrices. The study involved treating bamboo fibers with varying concentrations of plant ash solutions (5 %, 10 %, 20 %, and 30 % by mass fraction) and comparing the results with those from conventional NaOH treatment (5 % and 10 %). The results showed that plant ash treatment at a 20 % concentration significantly improved tensile strength by 14.16 % compared to untreated fibers, increased the crystallinity index to 74.31 %, and enhanced thermal stability, retaining more residual mass at high temperatures than NaOH-treated fibers. These improvements are attributed to the reduction in fiber polarity and better preservation of fiber structure. The findings suggest that plant ash, as a cost-effective and eco-friendly alternative to NaOH, can significantly enhance the mechanical and thermal properties of bamboo fibers, making them suitable for use in environmentally sustainable composite materials in construction, and other industries.

A cascaded process to upgrade bleached bamboo pulp into dissolving pulp and arabinoxylan

The dissolving pulp preparation from bleached kraft pulp while realizing the high-value application of hemicellulose fraction is of great significance for improving the overall economics of the process. This work proposed a two-step cascaded process of deep eutectic solvent (DES) pretreatment combined with mechanical refining for the co-production of dissolving pulp and arabinoxylan (AX) from bleached bamboo pulp. Results showed that using alkaline DES composed of quaternary ammonium hydroxide and urea prepared high-quality dissolving pulp (α-cellulose content of 97.7 %) while selectively extracting high-quality AX. The mechanical refining rapidly opened up the cellulose structure to increase its Fock reactivity to over 70.0 %. When 100 g bleached bamboo pulp was subjected to this technology route, the high yields of dissolving pulp (63.8 g) and AX (13.0 g) were respectively obtained. It was proposed that the tailored DES with different alkalinity could specifically produce dissolving pulp or AX which were more favorable for downstream application through distinct action pathways. The swelling effects of DES on the cellulose surface facilitated the subsequent mechanical fibrillation, allowing a synergistic enhancement of the reactivity. Thus, the integrated process provided a sustainable alternative for dissolving pulp upgrading while adding attractiveness by co-producing AX product stream.

Hemicellulose and unlocking potential for sustainable applications in biomedical, packaging, and material sciences: A narrative review

Hemicellulose, a complex polysaccharide abundantly found in plant cell walls, has garnered significant attention for its versatile applications in various fields including biomedical, food packaging, environmental, and material sciences. This review systematically explores the composition, extraction methods, and diverse applications of hemicellulose-derived materials. Various extraction techniques such as organic acid, organic base, enzyme-assisted, and hydrothermal methods are discussed in detail, highlighting their efficacy and potential drawbacks. The applications of hemicellulose encompass biodegradable films, edible coatings, advanced hydrogels, and emulsion stabilizers, each offering unique properties suitable for different industrial needs. Current challenges in hemicellulose research include extraction efficiency, scalability of production processes, and optimization of material properties. Opportunities for future research are outlined, emphasizing the exploration of new applications and interdisciplinary approaches to harness the full potential of hemicellulose. This comprehensive review aims to provide valuable insights for researchers and industry professionals interested in utilizing hemicellulose as a sustainable and functional biomaterial.

Selectively fractionate hemicelluloses with high molecular weight from poplar thermomechanical pulp by tetramethylammonium hydroxide

Selective fractionation of hemicelluloses is of great significance for realizing high-value application of hemicelluloses and comprehensive utilization of lignocellulosic biomass. Tetramethylammonium hydroxide (TMAH) solvent has been confirmed as a promising solvent to selectively fractionate hemicelluloses from holocellulose. Herein, TMAH solvent was adopted to pretreat poplar thermomechanical pulp (PTMP) for the selective fractionation of hemicelluloses and enhancement of enzymatic hydrolysis performance of residues. The maximal hemicelluloses yield (65.0 %) and excellent cellulose retention rate (93.3 %) were achieved after pretreatment by the 25 wt% TMAH solvent, while the delignification was only 33.9 %. The hemicelluloses fractions could be selectively fractionated with high molecular weights (109,800-118,500 g/mol), the contents of Klason lignin in them were low (3.2-5.9 %), and the dominating structure of them was 4-O-methylglucurono-β-D-xylan. Compared to the H2SO4 and NaOH methods, the hemicelluloses fractionated by TMAH method exhibited higher yields, more complete structures and higher molecular weights. Furthermore, the crystalline structure of cellulose practically remained stable, and the highest yield of enzymatic hydrolysis glucose was 57.5 %, which was 3.3 times of that of PTMP. The fractionation effectiveness of TMAH solvent was not significantly reduced after repeatedly recycling. This work demonstrated TMAH solvent could selectively fractionate hemicelluloses from PTMP and efficiently promote sustainable poplar-based biorefinery.

Cellulose Dissolution, Modification, and the Derived Hydrogel: A Review

The cellulose-based hydrogel has occupied a pivotal position in almost all walks of life. However, the native cellulose can not be directly used for preparing hydrogel due to the complex non-covalent interactions. Some literature has discussed the dissolution and modification of cellulose but has yet to address the influence of the pretreatment on the as-prepared hydrogels. Firstly, the "touching" of cellulose by derived and non-derived solvents was introduced, namely, the dissolution of cellulose. Secondly, the "conversion" of functional groups on the cellulose surface by special routes, which is the modification of cellulose. The above-mentioned two parts were intended to explain the changes in physicochemical properties of cellulose by these routes and their influences on the subsequent hydrogel preparation. Finally, the "reinforcement" of cellulose-based hydrogels by physical and chemical techniques was summarized, viz., improving the mechanical properties of cellulose-based hydrogels and the changes in the multi-level structure of the interior of cellulose-based hydrogels.

Synthesis of Porous Activated Carbon Doped with Tetramethylammonium Hydroxide: Evaluation of Excellent Gasoline Vapor Adsorption Performance and Activation Mechanism

The rapid urbanization and industrialization in China have led to an urgent dilemma for controlling urban air pollution, including the intensified emission of gasoline vapor into the atmosphere. Herein, we selected highland barley straw as a raw material and KOH and tetramethylammonium hydroxide (TMAOH) as activators to synthesize nitrogen-doped layered porous carbon (K-thAC) by a three-step activation method. The obtained K-thAC materials had a high specific surface area, reaching 3119 m2/g. Dynamic adsorption experiments demonstrated a superior adsorption capacity of up to 501 mg/g (K-thAC-25) for gasoline vapor compared with other documented carbon adsorbents. Moreover, adjusting the ratio of raw materials with a series of active ingredients could further improve the pore properties of the obtained K-thACs and their adsorption performance for gasoline vapor. Furthermore, the K-thAC materials were also characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), synchronous thermogravimetry (STA), X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption tests. This study synthesized a novel plant-based material to treat gasoline vapor pollution efficiently.