Cellulose最新文献

The hydroxypropyl cellulose embellished molybdenum disulfide (HPC/MoS₂) was prepared to remove europium (Eu) from the aqueous solution. Introducing hydroxypropyl cellulose into molybdenum disulfide can provide more functional groups and active sites to bind to Eu(III). The SEM images showed a rugged and uneven spherical structure of HPC/MoS₂ with a diameter of 4.5 μm. The high-magnification TEM picture further confirmed a nanolayered structure, showing that the material retained the two-dimensional layered structure of molybdenum disulfide. A new peak appeared in the XRD patterns after adsorption, which was attributed to Eu(III) entering the layers of HPC/MoS₂ by the pore canals. The adsorption of Eu(III) relied on pH, and the adsorption capacity of HPC/MoS₂ for Eu(III) attained 157.2 mg/g at 298 K. The Eu(III) removal mechanisms included Eu(III) entering the layers of HPC/MoS₂, electrostatic attraction, and forming complexes. This study can provide new insight into the design and application of two-dimensional nanomaterials for environmental pollution cleanup.

Innovative and environmentally sound materials are essential for wastewater remediation to ensure sustainability and drinking water quality. Hydrogels formed from cellulose alone or combined with hemicelluloses and lignin are an excellent choice. They are the primary components of lignocellulosic biomass, whose main source is wood. However, the dependence on wood as a source of lignocellulosic macromolecules is challenging since the trees’ growth requires years and continuous surveillance against deforestation. Therefore, the aim of this Overview was oriented towards non-woody biomass (NWB) to produce hydrogel sorbents, focusing on their potential application in wastewater treatment by removing heavy metals. Papers reporting the use of NWB, such as wheat and tobacco straw, sugarcane bagasse, and recycled cotton fabrics, were considered. The Overview assessed the deconstruction of the NWB, cellulose dissolution, hydrogel formation, and mechanism of heavy metals sorption. The hydrogels from NWB, primarily formed through radical polymerization, are rich in hydroxyl groups, which leads to efficient crosslinking and high sorption capacities. Further investigation on functionalization and novel approaches to creating hydrogels from NWB may enhance the sustainability side of hydrogel formation and its potential for removing heavy metals, offering a promising solution to wastewater treatment.

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Tracking mechanical microfibrillation in nanocellulose production is time-consuming due to a lack of quick characterization methods. This study investigates optical monitoring of the mechanical microfibrillation process by determining the dimensions of microfibrillated cellulose (MFC) particles on micron scale. Bleached hardwood pulp was microfibrillated using three sets of grinding discs in a six-stage pilot process, analyzing MFC characteristics as a function of specific energy consumption via image analysis. A laboratory-scale ultrafine grinder was also used for comparison. The degree of microfibrillation was assessed over a broad energy range using the equivalent diameter derived from the MFC length and width through image processing. The microfibrillation process adhered to Rittinger’s law, i.e., changes in the apparent specific surface area (SSA) were linearly proportional to the applied grinding energy. SSA, being inversely proportional to equivalent diameter, predicted MFC quality in terms of nanofilm strength properties. The optical fiber image analyzer proved suitable for online monitoring and control of microfibrillation processes. Despite resolution limits in detecting sub-micron particles, their proportion interrelates to the size of optically visible particles, covering industrial needs for mechanical microfibrillation.

Periodically disordered regions can be induced by drying in cellulose microfibrils of several plant species. In this study, cellulose nanocrystals were prepared from never-dried and oven-dried cellulose samples from Egeria densa by sulfuric acid hydrolysis and observed with transmission electron microscopy. Cellulose nanocrystals from never-dried samples were long (> 1 μm in length), curved smoothly, and had very few kinks. In contrast, cellulose nanocrystals from oven-dried samples were shorter (50–600 nm in length) and were almost entirely straight. These results indicated that never-dried cellulose microfibrils lacked the disordered regions along the microfibril and exhibited a continuous, low bending rigidity. Never-dried and oven-dried cellulose samples from E. densa were subjected to acid hydrolysis, dissolution in 1% LiCl/dimethylacetamide, and size-exclusion chromatography–multi-angle laser-light scattering analysis. After acid hydrolysis, oven-dried samples showed a significantly lower degree of polymerization than never-dried samples. In addition, oven-dried samples showed a unimodal and narrow molar mass distribution, whereas never-dried samples showed a bimodal distribution after acid hydrolysis. These results indicated that oven-drying induces the disordered regions along the cellulose microfibril and that the disordered regions are cleaved by acid hydrolysis.

The use of by-products from the wood industry as an alternative to obtaining cellulose, using an eco-friendly process is essential for the sustainable production of high value-added bioproducts. In this research, the cellulose/chondroitin sulfate membranes were obtained using saw dust as the cellulose source. Initially, cellulose was extracted using peracetic acid (PA) in one (Cel1) and two cycles (Cel2) and mercerized with NaOH. Analysis of the products obtained by X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR) and Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV–Vis DRS) confirmed that the extracted cellulose was type II and that the reduction of lignin (from 36 to 3.5%) did not depend on the number of bleaching cycles. Membranes with and without the addition of borax were obtained by dissolving cellulose in NaOH/urea/H2O (7/12/81% m/m), mixed with chondroitin sulfate (SC) in proportions 100/0; 90/10; 80/20 and 70/30 (% m/m). The effect of SC contents and the presence of borax on the properties of membranes produced was investigated. The results showed that the swelling ratio, equilibrium water content and kinetic mechanism of water absorption were influenced by the presence of borax and the amount of chondroitin sulfate. The results demonstrated that the properties of Cel/SC membranes could be modulated by the composition and had potential for application in the biomedical area.

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Materials with stimulus-responsive wettability are attracting increasing attention because of their potential applications in oil/water separation and oil spill remediation. Herein, a pH-responsive filter paper was rapidly fabricated by initially forming a complex between TiO₂ and octadecylamine, followed by immersion in an ethanolic solution of SiO₂ nanoparticles. The resultant filter paper exhibited superhydrophobicity and superoleophilicity in air when the solution pH was greater than 6.0, whereas it became superhydrophilic and superoleophobic when the solution pH was less than 2.0. The treated filter paper was used for the controllable separation of complex oil/water/oil ternary mixtures, demonstrating its strong response to pH changes. The pH-responsive filter paper effectively separated both immiscible oil/water mixtures and different kinds of oil-in-water emulsions with separation efficiencies exceeding 99%. The durability of the pH-responsive filter paper was demonstrated by its ability to maintain a separation efficiency of around 99%, even after 25 cycles of separating a typical emulsion of tetrachloromethane in water. The developed approach has the potential to provide innovative smart materials for the treatment of oil-contaminated wastewater.

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In this study, acetic anhydride and iodine were used as acetylating agents to produce cellulose acetate (CA) from cotton linter-dissolving pulp (LDP). The conditions for acetylation, as well as the crystallinity and reactivity of LDP with high cellulose purity, were investigated and compared with our previous research on low-grade pulp. The properties of the CA, including yield, degree of substitution (DS), differential scanning calorimetry (DSC) analysis, and film characteristics were examined. The results reveal that LDP due to its high cellulose purity (98%) and higher crystallinity, has significantly fewer low-degree polymerization (DP) chains than wood pulp, resulting in a higher molecular weight. Acetylation of LDP required more catalysts due to the reduced accessibility of hydroxy groups, leading to variable yields and degrees of substitution (DS) depending on iodine consumption and acetic anhydride ratios. Therefore, acetylation using a large amount of iodine as catalyst (8% of the pulp), adapted well to different types of pulp. Mechanical testing indicated that while increased catalyst usage initially improved film strength and transparency, excessive iodine led to degradation, reduced mechanical properties, and increased brittleness. These findings suggest that both high and low-purity pulps can be effectively utilized for CA film production, potentially reducing costs in industrial applications. Overall, this study demonstrates the flexibility of the acetylation process when iodine is used as a catalyst.

Engineering the active layer of pressure sensors with micro-nano structures is increasingly important in improving their sensing properties, such as sensitivity and detection range. However, existing structures based on template methods continue to face manufacturing challenges and uncontrolled structures, making it difficult to optimize sensing performance. To address the aforementioned shortcomings, this study proposes highly tunable metallic silver copper micro-nano structures adapted on cotton fabric (AgCu/cotton) to adjust the interfacial contact sites and optimize the sensing properties. The shape, size, and distribution of the metallic AgCu nano structures are precisely regulated, and various distinctive morphologies including two-dimensional (2D) nanosheet stacking, three-dimensional (3D) irregular protrusions, and nanoparticle aggregation were obtained. Specifically, the 3D irregular protrusions of varying heights and shapes (nanosheets, nanoparticles, and so on), encouraging multiple deformations and enhanced interfacial contact sites. On the other hand, the hierarchical porous structure of cotton fabric enhances structural compressibility. Collectively, the synergistic results of the 3D irregular protrusions and the hierarchical porous structure allow for a high sensitivity (115.65 kPa⁻¹), a quick response time (500 ms), and outstanding stability (2000 cycles). The above sensing properties enable the pressure sensor to be successfully applied in joint movement detection and swallowing recognition. The discovery could pave the way for a more cost-effective and widespread approach to a controlled and improved piezoresistive pressure sensor.

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We herein develop a highly morphology-controlled AgCu/cotton flexible pressure sensor with an economical strategy toward superior sensing performance. Such regulated morphology is responsible for optimized contact sites and structural deformation, resulting in a high sensitivity of 115.65 kPa⁻¹ over 2–7.5 kPa, and showing great potential in various human motion detections.

Living organisms are constantly exposed to cosmic, terrestrial, and internal sources of radiation. As a result, they have developed natural radioprotective mechanisms. However, in some cases, these mechanisms may not be sufficient. Elevated doses and prolonged exposure to radiation, such as during radiotherapy or in extreme environments like spaceflight, can cause damage to DNA and increase the abundance of reactive oxygen species, which can affect biological processes. In contrast to synthetic ingredients, naturally produced radioprotective materials have good biocompatibility and are easy to recycle. This work investigates the radioprotective properties of the hydrogel biofilm produced by the kombucha microbial consortium. The shielding properties of kombucha’s bacterial cellulose (KBC) were examined using gamma quanta with energies ranging from 122 to 1408 keV and an AmBe neutron source. The native form of KBC contains more than 80% water content. To enhance the radioprotection of kombucha’s biofilm, metallic components (K, Fe, Mxenes) and biological additives were tested. Rhodobacter sphaeroides and Synechocystis sp. PCC6803, which are resistant to oxidative stress, were added to the cultivation media. Physical properties were characterized using microscopy, ion leaching, and contact angle measurements. Post-processed dried KBC wristbands were analyzed for absorption parameters to enhance protective shielding. Possible levels of radioprotection for various types of bacterial cellulose thickness and forms were computed based on the obtained results. The findings encourage the use of bacterial cellulose in a circular economy for future bioregenerative systems.

This work deals with the strain-rate dependent characterization of paper under uniaxial tension at high strain-rates. Experiments were performed involving a Split Hopkinson bar for high strain-rate testing, comparing the results with conventional quasi-static tests. Tests were conducted in a strain-rate range between 0.0083 and 212 s⁻¹, which is equivalent to testing velocities between 0.0003 and roughly 13.6 m/s. For the first time the change in tensile behaviour of paper is comprehensively characterized and modelled, using the Cowper-Symonds model for strain-rate hardening. The experimental tests showed that the tensile strength as well as the initial stiffness were gradually increasing with increasing strain-rate. The increase in tensile strength between the lowest and the highest strain-rate was 58% on average whereas the mean increase in stiffness between these two strain-rates was almost 115%. Regarding the fracture strain, it was observed that it significantly decreases with increasing strain-rate. While the average fracture strain of the quasi-static tests was at roughly 6% it was close to 3% for the dynamic tests. In case of the Split Hopkinson bar tests, high-speed videos of the samples were made to determine their elongation via target tracking and digital image correlation (DIC). We found that strain localization, which is a highly relevant mechanism for quasi-static tensile failure, is likely related to short term plastic creep of the material as strain localization nearly entirely disappears at high loading rates of paper.