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Periodate oxidation introduces aldehyde functionality to cellulose. The use of dialdehyde cellulose has been demonstrated for crosslinking and as a chemical intermediate towards functionalized cellulose. Commercially available cellulose nanocrystals (CNCs) typically carry a surface sulfate half-ester functionality, which results from their manufacture via sulfuric acid hydrolysis and subsequent esterification. The sulfate half-ester group is a bulky group carrying a net negative charge above pH 2 that modifies the colloidal and electro-chemical properties of the CNCs. Periodate oxidation is regioselective to the bond between carbons in positions 2 and 3 in the anhydroglucose unit while the sulfate half-ester groups are mostly considered to be located in carbon in position 6. This regioselectivity could be the reason why the role played by the sulfate half-ester group on modification by periodate oxidation has not previously been elucidated. Here, the influence of the sulfate half-ester on the oxidation of CNCs, which is shown to steer the oxidation kinetics and the properties of the resulting materials, is studied. Conventional physicochemical analysis of the oxidant consumption is accompanied by elemental analysis, Fourier-transform infrared, X-ray photoelectron and solid-state nuclear magnetic resonance spectroscopy, and wide-angle x-ray scattering analyses; the zeta potential is used to characterize the colloidal properties of the suspensions and atomic force microscopy for determining particle dimensions. The presence of the sulfate half-ester group decreases the rate of oxidation. However, the content of the sulfate half-ester groups decreases when degree of oxidation reaches approx. 50%. We demonstrate that the CNC surfaces are affected by the oxidation beyond the C2–C3 bond cleavage: insight into the kinetics of the oxidation process is a prerequisite for optimizing CNC oxidation. [ABSTRACT FROM AUTHOR]

Future biorefineries are facing the challenge to separate and depolymerize biopolymers into their building blocks for the production of biofuels and basic molecules as chemical stock. Fungi have evolved lignocellulolytic enzymes to perform this task specifically and efficiently, but a detailed understanding of their heterogeneous reactions is a prerequisite for the optimization of large-scale enzymatic biomass degradation. Here, we investigate the binding of cellulolytic enzymes onto biopolymers by surface plasmon resonance (SPR) spectroscopy for the fast and precise characterization of enzyme adsorption processes. Using different sensor architectures, SPR probes modified with regenerated cellulose as well as with lignin films were prepared by spin-coating techniques. The modified SPR probes were analyzed by atomic force microscopy and static contact angle measurements to determine physical and surface molecular properties. SPR spectroscopy was used to study the activity and affinity of Trichoderma reesei cellobiohydrolase I (CBHI) glycoforms on the modified SPR probes. N-glycan removal led to no significant change in activity or cellulose binding, while a slightly higher tendency for non-productive binding to SPR probes modified with different lignin fractions was observed. The results suggest that the main role of the N-glycosylation in CBHI is not to prevent non-productive binding to lignin, but probably to increase its stability against proteolytic degradation. The work also demonstrates the suitability of SPR-based techniques for the characterization of the binding of lignocellulolytic enzymes to biomass-derived polymers. [ABSTRACT FROM AUTHOR]

Microcrystalline cellulose (MCC) is a semi-crystalline material with inherent variable crystallinity due to raw material source and variable manufacturing conditions. MCC crystallinity variability can result in downstream process variability. The aim of this study was to develop models to determine MCC crystallinity index (%CI) from Raman spectra of 30 commercial batches using Raman probes with spot sizes of 100 µm (MR probe) and 6 mm (PhAT probe). A principal component analysis model separated Raman spectra of the same samples captured using the different probes. The %CI was determined using a previously reported univariate model based on the ratio of the peaks at 380 and 1096 cm−1. The univariate model was adjusted for each probe. The %CI was also predicted from spectral data from each probe using partial least squares regression models (where Raman spectra and univariate %CI were the dependent and independent variables, respectively). Both models showed adequate predictive power. For these models a general reference amorphous spectrum was proposed for each instrument. The development of the PLS model substantially reduced the analysis time as it eliminates the need for spectral deconvolution. A web application containing all the models was developed. [ABSTRACT FROM AUTHOR]

This study investigates the role of drying method and dissolving solvent has on the properties of regenerated cellulose fibres, leading to the preparation of porous cellulose fibres. The fibres are produced by wet spinning using 1-butyl-3-methylimidazolium acetate (BmimAc) as the solvent, and then dried using freeze drying or supercritical drying resulting in highly porous fibres. The properties of these fibres are compared to the traditional air-dried regenerated cellulose fibre. It was found that freeze drying produced fibres with micron pores on the surface and nanopores within the core, whereas supercritical-dried fibres had a smooth surface and a nanoporous core. The addition of DMSO to the spinning dope for supercritical dried fibres reduced the fibre diameter under identical draw conditions and increased the surface area to 260 m2/g. [ABSTRACT FROM AUTHOR]

Knowledge about the carbohydrate composition of pulp and paper samples is essential for their characterization, further processing, and understanding the properties. In this study, we compare sulfuric acid hydrolysis and acidic methanolysis, followed by GC–MS analysis of the corresponding products, by means of 42 cellulose and polysaccharide samples. Results are discussed and compared to solid-state NMR (crystallinity) and gel permeation chromatography (weight-averaged molecular mass) data. The use of the hydrolysis methods in the context of cellulose conservation science is evaluated, using e-beam treated and artificially aged cellulose samples. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is a polymer with interesting conformation and properties. BC can be obtained in different shapes and is easily modified by chemical and physical means, so its applications in the production of new materials and nanocomposites for different purposes have been in the focus of many research projects. However, one of the major challenges to address in bacterium-derived polymer technology is to find suitable carbon sources as substrates that are cheap and do not compete with food production for achieving large scale industrial applications. Agricultural wastes are defined as the residues from the growing and processing of raw agricultural products such as crops, fruits, vegetables and dairy products. Their composition can vary depending on the type of agricultural activity and harvesting conditions, but these residues are suitable for the production of BC. The aim of this review is to give insight into the production of BC using agro-wastes and an overview of the most interesting and novel applications of this biopolymer in different areas i.e. environmental applications, optoelectronic and conductive devices, food ingredients and packaging, biomedicine, and 3D printing technology. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) were surface modified with benzoic acid anhydride (BzAnh) at room temperature in 48-h reaction time. FTIR spectroscopy confirmed the high degree of modification of the CNCs with BzAnh, while 13C CP MAS NMR showed that the total degree of modification was 16%, indicating that the degree of surface modification of the CNCs was very high (estimated to be 50% or even higher). 2D 1H-13C CP-HETCOR MAS NMR and 13C-detected proton spin-diffusion (PSD) experiments confirmed that BzAnh reacted mainly with –CH2–OH groups in the amorphous regions of CNC nanocrystals. The crystallinity indices of unmodified and BzAnh-modified CNCs showed little difference, indicating that the modification did not destroy crystalline domains, thus confirming NMR results that the esterification reaction occurred mainly in the amorphous cellulose regions. Unmodified and BzAnh-modified CNCs were used to produce nanocomposites with polystyrene (PS) by melt processing at 200 °C. SEM microscopy confirmed the improved compatibility of BzAnh-modified CNCs with PS matrix compared to PS nanocomposites prepared with unmodified CNCs. The results of tensile tests showed that the addition of BzAnh-modified CNCs increased the Young's modulus and tensile strength of the composites, while unmodified CNCs showed deterioration in mechanical properties. The addition of 5 wt% CNCs to the PS matrix resulted in a 30% improvement in tensile strength and a 23% increase in Young's modulus. The increased compatibility and improved mechanical properties of BzAnh-modified CNCs were attributed to the intense entanglement of PS chains and BzAnh-modified CNCs due to π–π interactions between benzene rings. [ABSTRACT FROM AUTHOR]

Wood is an increasingly important material in the sustainable transition of societies worldwide. The performance of wood in structures is intimately tied to the presence of moisture in the material, which directly affects important characteristics such as dimensions and mechanical properties, and indirectly its susceptibility to fungal decomposition. By chemical modification, the durability of wood in outdoor environments can be improved by reducing the amount of moisture present. In this study, we refined a well-known chemical modification with acetic anhydride and showed how the spatial distribution of the modification of Norway spruce (Picea abies (L.) Karst.) could be controlled with the aim of altering the wood-water interactions differently in different parts of the wood structure. By controlling the reaction conditions of the acetylation it was possible to acetylate only the cell wall-lumen interface, or uniformly modify the whole cell wall to different degrees. The spatial distribution of the acetylation was visualised by confocal Raman microspectroscopy. The results showed that by this targeted acetylation procedure it was possible to independently alter the wood-water interactions in and outside of cell walls. The cell wall-lumen interface modification altered the interaction between the wood and the water in cell lumina without affecting the interaction with water in cell walls while the uniform modification affected both. This opens up a novel path for studying wood-water interactions in very moist environments and how moisture distribution within the wood affects its susceptibility towards fungal decomposition. [ABSTRACT FROM AUTHOR]

With an annual production of more than 400 million tons, paper is the main product of the largest biorefinery process industrially implemented. Enzymes have been used for pulp refining to dramatically reduce energy consumption. However, exact mechanisms related to the individual enzymes are hardly understood. Yet, this knowledge would be important to predict enzyme performance in industrial processes. Three commercial refining enzyme formulations showed different endoglucanase (1.25 nkat mg−1–13.7 nkat mg−1), β-glucosidase (0.57 nkat mg−1–1.34 nkat mg−1) and xylanase activities (1.78 nkat ml−1–62.1 nkat mg−1) on model substrates. Additionally, distinct amounts of reducing sugars from hardwood sulfate pulp were released. Endoglucases were purified from each formulation by using hydrophobic interaction and anion exchange chromatography and showed molecular weights from 20 to 55 kDa and specific activities ranging between 3.11 and 26.3 nkat mg−1 according to endoglucanase specific derivatized cellopentaose (CellG5). Refining trials of hardwood sulfate pulp were conducted using a PFI laboratory mill and fiber properties such as degree of refining or fiber length and properties of formed sheets like tensile index were monitored. Thereby, enzymes were dosed based on identical endoglucanase activity on CellG5. Enzyme formulations and purified endoglucanases led to an increase of the degree of refining of up to 47.9 [°SR] at 6000 PFI revolutions while the tensile index was improved by up to 76.0 Nm g−1. In summary, refining effects can be primarily attributed to endoglucanases indicating activity on CellG5 being a suitable parameter for enzyme dosing. [ABSTRACT FROM AUTHOR]

Lignocellulose based nanomaterials are emerging green biosolids commonly obtained from wood pulp. Alternative feedstocks, such as as unavoidable food waste, are interesting resources for nano/microfibers. This research reports the production and characterization of microfibrillated lignocellulose (MFLC) from cassava peel (CP) and almond hull (AH) via acid-free microwave-assisted hydrothermal treatment (MHT) at different temperatures (120–220 °C). During processing, the structural changes were tracked by ATR-IR, TGA, XRD, 13C CPMAS NMR, zeta potential, HPLC, elemental analysis (CHN; carbon, hydrogen and nitrogen), TEM and SEM analyses. The microwave processing temperature and nature of feedstock exerted a significant influence on the yields and properties of the MFLCs produced. The MFLC yields from CP and AH shifted by 15–49% and 31–73%, respectively. Increasing the MHT temperature substantially affected the crystallinity index (13–66% for CP and 36–62% for AH) and thermal stability (300–374 °C for CP and 300–364 °C for AH) of the MFLCs produced. This suggested that the MFLC from CP is more fragile and brittle than that produced from AH. These phenomena influenced the gelation capabilities of the fibers. AH MFLC pretreated with ethanol at low temperature gave better film-forming capabilities, while untreated and heptane pretreated materials formed stable hydrogels at solid concentration (2% w/v). At high processing temperatures, the microfibrils were separated into elementary fibers, regardless of pretreatment or feedstock type. Given these data, this work demonstrates that the acid-free MHT processing of CP and AH is a facile method for producing MFLC with potential applications, including adsorption, packaging and the production of nanocomposites and personal care rheology modifiers. [ABSTRACT FROM AUTHOR]

Inappropriate discharge of industrial wastewater and household effluent has led to an accumulation of hazardous organic substances, oil and grease, heavy metal ions, dyes, and leftover pharmaceutical products in the aquatic environment. To mitigate the adverse effects of polluted water, various techniques have been implemented for physical, chemical, and biological wastewater treatments. In chemical wastewater treatments, utilizing polymers are among the most common pathways, in which cellulose-derived materials as one of the abundantly available lignocellulosic constituents have gained much interest for the applications. As environmental remediation agents, cellulose derivatives have great potential due to their biocompatibility, excellent mechanical properties, environmental friendliness, economic viability, low toxicity, and robustness. In a chemical wastewater treatment, cellulose derivatives can be valorized to various industrial applications, such as membrane technology, absorption and adsorption process, flocculant, a catalyst for chemical reaction, and disinfecting agent. In this review paper, various types of utilization methods of cellulose derivatives, ranging from nano, micro, and natural form in industrial wastewater and household effluent treatment, are extensively discussed. In addition, the cellulose performance in adsorption, filtration is also briefly elaborated and then compared with those of the conventional polymer-based materials, such as polyether sulfone (PES), Polyvinylidene fluoride (PVDF), and carbon nanofiber (CNF). [ABSTRACT FROM AUTHOR]

Infrared photo-induced force microscopy (IR PiFM) was applied for imaging ultrathin sections of Norway spruce (Picea abies) at 800–1885 cm−1 with varying scanning steps from 0.6 to 30 nm. Cell wall sublayers were visualized in the low-resolution mode based on differences in their chemical composition. The spectra from the individual sublayers demonstrated differences in the orientation of cellulose elementary fibrils (EFs) and in the content and structure of lignin. The high-resolution images revealed 5–20 nm wide lignin-free areas in the S1 layer. Full spectra collected from a non-lignified spot and at a short distance apart from it verified an abrupt change in the lignin content and the presence of tangentially oriented EFs. Line scans across the lignin-free areas corresponded to a spatial resolution of ≤ 5 nm. The ability of IR PiFM to resolve structures based on their chemical composition differentiates it from transmission electron microscopy that can reach a similar spatial resolution in imaging ultrathin wood sections. In comparison with Raman imaging, IR PiFM can acquire chemical images with ≥ 50 times higher spatial resolution. IR PiFM is also a surface-sensitive technique that is important for reaching the high spatial resolution in anisotropic samples like the cell wall. All these features make IR PiFM a highly promising technique for analyzing the recalcitrant nature of lignocellulosic biomass for its conversion into various materials and chemicals. [ABSTRACT FROM AUTHOR]

The influence of caustic mercerization (CM) and liquid ammonia (LA) treatments on the properties of reactively dyed cotton fabrics were schematically studied. The cotton fabrics were dyed using different commercial reactive dyes such as Reactive Red 2 (R2), Reactive Blue 21 (B21), and Reactive Orange 5 (O5) via industrial dyeing procedures. The dyed fabrics were then treated using 260 g·L−1 of caustic soda solution at 23 °C for 180 s and pure LA at −40 °C for 3 min in slack and tension conditions. The dyeing properties of the fabrics such as dye removal percentage, color strength, color uniformity, reflectance, and fastness properties (washing, rubbing, hot pressing and light) were examined. The changes in tensile strength, elongation, bending property, decomposition temperature, crystal structure, and surface morphology of the samples were also investigated using a tensile strength tester, thermogravimetric analyzer (TGA), scanning electron microscope (SEM), and an X-ray diffractometer (XRD). Results revealed that the fabric dyed with O5 showed the best stability in CM and LA treatment, and the color strength and color uniformity of the dyed fabrics increased extensively after both treatments, while the reflectance of the fabrics decreased. The washing and rubbing fastness of the fabrics were also improved, which was mainly attributed to the diffusion of the dye molecules inside the fibers and enhanced bonding between fiber and dye molecules. The fastness to hot pressing and light was unaffected and all the samples retained fastness rating between 4 and 5 after being post-treated with the CM and LA, respectively. The tensile strength of the fabrics improved from 287 to 291 and 301 N, and the elongation at break increased from 11 to 21.5 and 26% after CM and LA treatment in slack conditions, respectively. Additionally, the tensile strength of the fabrics improved from 287 to 312 and 330 N, and the elongation at break increased from 11 to 12% after applying tension during both treatments. However, the total bending length and total flexural rigidity of the samples slightly increased after both the treatments either treated with or without tension, which was mainly attributed to the orientation of the cellulose microfibril angle along the fiber axis. The surface morphology and X-ray diffraction examination revealed that the treated samples consisted of smooth rod-like structure and the cellulose I allomorph was converted to cellulose II and cellulose III after CM and LA treatments. This developed treatment method could have application potential within the textile wet-processing industry, as it could be used to improve the dyeing properties and mechanical properties of cotton fabrics. [ABSTRACT FROM AUTHOR]

Intelligent hydrogels with multifunctions including biocompatibility, good mechanical property, photothermal property, sustained drug delivery ability, and antibacterial property are urgently needed in the biomaterial fields. Herein, mesoporous polydopamine (MPDA) nanoparticles were wrapped by polyethyleneimine-modified cellulose nanocrystals (PCNC) and then physically crosslinked in cellulose nanofibrils (CNFs) hydrogel, obtaining a novel MPDA@PCNC/CNFs composite hydrogel with a double packing structure for controlled drug release. Tetracycline hydrochloride (TH) was selected as the drug model and it was loaded on MPDA nanoparticles. PCNC was warped outside surface of MPDA nanoparticle, which was used to prolong drug release time and reinforce the mechanical strength of MPDA@PCNC/CNFs composite hydrogel. Results presented that the mechanical strength of MPDA@PCNC/CNFs composite hydrogel was 3.5 times stronger than that of pure CNFs hydrogel. Burst release was reduced and drug delivery time of MPDA@PCNC/CNFs composite hydrogel was 3 times and 1.25 times longer than that of CNFs hydrogel and polydopamine/CNFs composite hydrogel, respectively. The drug delivery behavior of the MPDA@PCNC/CNFs composite hydrogel could be controlled by near infrared (NIR) light irradiation and acidic pH condition. Korsmeyer-Peppas model could be used to describe the drug delivery kinetics of the MPDA@PCNC/CNFs composite hydrogel. Fick's diffusion was the main drug delivery mechanism. Moreover, MPDA@PCNC/CNFs composite hydrogel was found to have good biocompatibility. The as-fabricated composite hydrogel with a double encapsulation structure and unique pH and NIR responsiveness can be applied as a promising drug release carrier, and it may also has potential applications in the fields of physical and chemical therapies. [ABSTRACT FROM AUTHOR]

Efficient separation of carbohydrates and lignin, and converting them into valuable products are still major challenges for biorefinery commercialization. In this paper, organic acid-catalyzed hydrolysis of corn stalk was carried out as the first step of biorefinery. The hydrolysis behavior of lignocellulose from different tissues of corn stalk under different conditions (e.g., acid species and other process parameters) has been deeply analyzed. The results showed that the dissociation constants (pKa) were closely related to the hydrolysis of sugars, and oxalic acid had significant degradation ability on carbohydrates. Moreover, two robust models have been developed for monitoring the hydrolysis kinetics of carbohydrates in corn bark and pith. Lastly, the residue solids-driven activated carbon materials have also been developed for application in the fields of energy storage and environmental protection. This work provides a waste-free biorefinery reference for high-value utilization of corn stalk or other lignocellulose based on organic acid pretreatment. [ABSTRACT FROM AUTHOR]

The main aim of this study was to introduce a new sustainable natural cellulosic raw material source to the benefits of the textile and composite industry. For this purpose, natural cellulosic fibers were extracted from Trachelospermum jasminoides (TJ) plant and the characterization of the fibers were carried out. Detailed physical, chemical, and instrumental tests were applied for better understanding of the fiber properties. The chemical bonds of the TJ fibers were determined with FTIR. Crystallographic properties were analyzed with XRD. Surface morphology was monitored with SEM and optic microscope images, cotton-like ribbon shape of the TJ elemental fibers was observed. TGA, DTA and DSC were utilized to understand the thermal degradation behavior, the maximum degradation temperature of TJ fiber was determined as 338.2 °C. Chemical tests were applied for the determination of the chemical composition of the TJ fibers. The cellulose content of the fiber was determined as 62.7%. Mechanical characteristics of the fibers were investigated with tensile tests which supplied information about strength, Young's modulus and elongation. The tensile strength of TJ fibers was 404 MPa. Pull-out tests were applied to both raw and NaOH treated fibers for evaluation of the surface interaction of TJ fibers with polymer matrix in epoxy composites. NaOH treatment 31% increased the interfacial shear strength. [ABSTRACT FROM AUTHOR]

Due to the compact tissue structure and stable molecule structure of plant fiber, converting fiber into high value-added products in current biomass utilization is still challenging, which restricts the application of many fiber-based composite materials. Herein, chemical impregnation and two-step mechanical refining (1st mechanical refining and 2nd mechanical refining) were proposed to solve this problem. The pondcypress (taxodium ascendens) fibers containing multiple surface active sites were prepared, based on the degradation and dissociation effects of alkaline hydrogen peroxide (AHP) and disc milling. The prepared fibers showed the intact spatial structure with excellent cellulose accessibility. It was found that the degradation of lignin and hemicellulose (excluding glucan) was 12.09% and 60.45%, respectively, at the optimized dosage of 10% H2O2 and 17.5% NaOH, in which the treated fibers remained high cellulose content. As expected, the cellulose accessibility was increased from 6.42% (raw fiber) to 47.26% after the treatment. Significantly, the treated fibers displayed higher specific surface area and active hydroxyl content (1.49 × 10–3 mol/g) due to the exposure of internal cell wall. This makes decomposed fibers an interesting candidate of ideal carrier for fiber composite. [ABSTRACT FROM AUTHOR]

The arrangement of cellulose molecules in natural environment on the nanoscale is still not fully resolved, with longitudinal disorder in cellulose microfibrils (CMF) being one relevant question. Particularly the length of the dislocated cellulose segments in CMFs is still under debate. Using molecular dynamics simulations, we are first investigating the phenomenon of pseudo-recrystallization of dislocated cellulose regions after cleavage of CMFs. Based on our simulations we propose that 3–4 glucose residues bordering to each side of a cellulose nanocrystal are actually reorganizing to a quasi-crystalline state, which are corroborating recent analytical investigations reporting an increase in crystallinity after acid vapor hydrolysis of CMFs. Combining our molecular dynamics simulation results with these analytical data we can estimate the length of the dislocated cellulose segments in CMFs. We propose that, for the investigated sources of biomass (cotton and ramie), the dislocation lengths are between 3.1–5.8 nm equaling to 6–11 glucose residues in the cellulose crystallites. [ABSTRACT FROM AUTHOR]

We report the preparation of highly compressible and elastic piezoelectric aerogels of carboxylated cellulose nanocrystals (CNCs). Aqueous CNC dispersions containing polyethyleneimine and crosslinker were frozen isotropically to yield isotropic aerogels, while oriented aerogels were prepared by directional freezing. These aerogels were highly flexible and porous (~ 85% void fraction), exhibiting greater than 90% recovery at 50% compressive strain even after 100 compression–decompression cycles. Since such aerogels with low bulk modulus and high anisotropy would be an ideal platform for leveraging the piezoelectric properties of CNCs, we used them to prepare piezoelectric nanogenerator devices and determined their energy transduction behavior. Anisotropic aerogels led to an enhanced open-circuit voltage of 840 mV (at ~ 8 N applied force), which is over 2.6 times higher than isotropic aerogels (320 mV). The energy density of anisotropic aerogels was around 52 nW/cm2, representing outstanding piezoelectric performance for cellulose-based aerogels. Such aerogels with high compressibility, elastic recovery and exceptional piezoelectric performance could have potential applications in sensors, wearable electronics, etc. [ABSTRACT FROM AUTHOR]

Bamboo, with a high cellulose content comparable to that of wood, is a potential feedstock for biofuel and nanocellulose production. Mechanically isolated bamboo fibers and parenchyma cells exhibited remarkable differences in enzymatic hydrolysis efficiency as reported in a recent comparative study. It was assumed that cellulose microfibrils in bamboo fibers and parenchyma cells differ in their supramolecular structures. In the present study, X-ray diffraction and solid-state CP/MAS13C NMR studies indicated that, the two types of cells showed similar cellulose crystallinity index. The cellulose from bamboo fibers and parenchyma cells also exhibited differences in microfibril sizes, with lateral sizes of ca. 26.0–41.3 Å and ca. 22.7–39.3 Å for bamboo fibers and parenchyma cells respectively. It was further found that cellulose chains in bamboo fibers were more closely packed, supported by its smaller d-spacing than that of parenchyma cell cellulose. In addition, FT-IR and NMR spectroscopy revealed that there was a higher Iβ content in fibers than parenchyma cells. These differences in the crystalline structure of cellulose should be related to the lower recalcitrance to chemical degradation of parenchyma cells compared to bamboo fibers. These differences in the crystalline structure of cellulose should be related to the lower recalcitrance to chemical degradation of parenchyma cells compared to bamboo fibers. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs) have attracted tremendous attention because of their excellent chemical and physical properties and due to their renewability and sustainability. This material can be extracted from agricultural by-products such as rice straw, banana tree, or bagasse. Rice straw was selected as the raw material in this study. Initially, a large amount of lignin must be removed by an alkaline process to obtain a slurry. Thereafter, a green bleaching process can be used to remove the remaining lignin in the slurry. An UV-emitting diode with 365 nm wavelength assisted the oxidation reaction of the H2O2 solution without the use of chlorine-containing chemical bleach. The reaction required only 2.5 h to obtain high-purity cellulose and successfully enhanced the yield. Transmission electron microscopy images showed that the CNCs from rice straw were ~ 100 nm long and 10–15 nm wide. The crystalline index and degradation temperature of CNCs were 83.8% and 257 °C, respectively. [ABSTRACT FROM AUTHOR]

Steam explosion is a useful method to soften and dimensionally stabilizing wood. A significant increase in air permeability and sound absorption capability of steam-exploded palmwood compared to untreated palmwood is observed due to changes in cell wall. Cell wall's changes are characterized by instrumental techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscope and gas permeability by capillary flow porometry and sound absorption coefficient by two-microphone transfer function method. The average increase in air permeability (259.3%) and sound absorption coefficient (52.33% at frequency range of 250–6400 Hz) of steam-exploded samples is higher than that of untreated samples. Color of steam-exploded woods become black due to chemical reactions in cell wall during steam explosion. The color change, air permeability and sound absorption coefficient of wood are correlated with the findings. These results suggest that low-pressure steam explosion could be considered as an effective technique for improving the air permeability and sound absorption capability of palmwood in the longitudinal direction. This approach could be useful to manufacture sound absorption board to control the acoustical housing environment. [ABSTRACT FROM AUTHOR]

Given that terahertz (THz) radiation responds to intermolecular forces such as hydrogen bonds, THz time-domain spectroscopy (THz-TDS) has expanded possibilities in cellulose research. In this study, THz-TDS was used to investigate the crystallinity of three types of cellulose-based materials. Microcrystalline cellulose (MCC) and wood were ball milled at different times, and pseudo-wood was a mixture of MCC and lignin of different mass fractions. All the samples showed peaks at 3.04 THz in the THz mass absorption coefficient spectra. Further, the spectra from 2.79 THz to 3.32 THz were cut out and detrended by subtraction from a baseline. The integrated intensity of the detrended spectra showed a correlation with the mass fraction of lignin of the pseudo-wood samples, and ball milling time of the MCC and wood samples. The correlation was similar with the crystallinity index calculated from X-ray powder diffraction. Moreover, the original wood sample without ball milling had an integrated intensity that was about 30% that of the original MCC sample, matching with the cellulose concentration of the wood (about 30% to 40%). We normalized the integrated intensity of 2.79 THz to 3.32 THz into 1 to 0 by a min–max algorithm and proposed a new "index" for evaluating crystallinity. [ABSTRACT FROM AUTHOR]

Herein, cellulose nanofibrils (CNF), alkali lignin (AL), and montmorillonite (MMT) were used to produce reinforced polyvinyl alcohol (PVA) hydrogels. The effects of MMT and AL contents on the rheological properties of reinforced hydrogel were studied. Compared with PVA/CNF hydrogel, the storage modulus of 40 wt% MMT-reinforced PVA hydrogel was increased by 41.4%. The rheological properties of MMT-enhanced PVA hydrogel could be adjusted by the variation of MMT loading. Also, as the PVA matrix had a synergistic effect with the embedded MMT and AL, the composite hydrogel demonstrated high efficiency in the removal of methylene blue dye (MB) from wastewater. Adsorption tests conducted at various time intervals (60–360 min) show that the hydrogels containing same content of MMT had higher removal efficiency. The MB adsorption of PVA/2CNF-0Li-40MMT was over 98.0%, whereas its adsorption equilibrium time and maximum adsorption capacity (qm) were 360 min and 67.2 mg/g, respectively. However, an extremely high content of MMT reduced the MB adsorption rate. [ABSTRACT FROM AUTHOR]

A modified TEMPO-catalyzed oxidation of the solvent-exposed glucosyl units of cellulose to uronic acids, followed by carboxyl reduction with NaBD4 to 6-deutero- and 6,6-dideuteroglucosyl units, provided a robust method for determining relative proportions of disordered amorphous, ordered surface chains, and anhydrous core-crystalline residues of cellulose microfibrils inaccessible to TEMPO. Both glucosyl residues of cellobiose units, digested from amorphous chains of cellulose with a combination of cellulase and cellobiohydrolase, were deuterated, whereas those from anhydrous chains were undeuterated. By contrast, solvent-exposed and anhydrous residues alternate in surface chains, so only one of the two residues of cellobiosyl units was labeled. Although current estimates indicate that each cellulose microfibril comprises only 18 to 24 (1 → 4)-β-d-glucan chains, we show here that microfibrils of walls of Arabidopsis leaves and maize coleoptiles, and those of secondary wall cellulose of cotton fibers and poplar wood, bundle into much larger macrofibrils, with 67 to 86% of the glucan chains in the anhydrous domain. These results indicate extensive bundling of microfibrils into macrofibrils occurs during both primary and secondary wall formation. We discuss how, beyond lignin, the degree of bundling into macrofibrils contributes an additional recalcitrance factor to lignocellulosic biomass for enzymatic or chemical catalytic conversion to biofuel substrates. [ABSTRACT FROM AUTHOR]

The dissolution of cellulose is a critical step for the efficient utilization of this renewable resource as a starting material for high value-added chemical and biofuel production. In this study, three aprotic solvents were chosen to couple with three ionic liquids (ILs) as binary solvent systems for cellulose dissolution. The percentage of dissolved cellulose of each IL/co-solvent was evaluated and the crystallinity index (CrI) of the undissolved cellulose residues after dissolution were investigated by XRD. Dimethyl sulfoxide exhibited the most effective synergistic interaction with the ILs among three co-solvents for cellulose dissolution. In general, the higher percentage of dissolved cellulose of the IL/co-solvent binary system, the lower CrI value of the undissolved cellulose residue after dissolution. In addition, the dissolution of cellulosic materials with different crystallinity and degree of polymerization indicated that the crystallinity of a cellulosic material played a more dominating role than degree of polymerization in its dissolution process. The hydrogen bond basicity (β value) of selected IL/co-solvent binary system was also calculated. The results showed that the β value of a binary IL/co-solvent system exhibited different trend than neat IL in terms of the cellulose dissolution ability, which should be attributed to the co-solvent effect. [ABSTRACT FROM AUTHOR]

Fragaria chiloensis (Chilean strawberry) fruit has been described as a fruit with excellent organoleptic properties, highlighting its flavor and aroma. However, the fruit has a high softening rate. Fruit softening during the ripening process is a consequence of the solubilization and depolymerization of cell wall components. In the present work, we performed a comparative study of the changes in the physiological properties of the cell wall-associated polysaccharide contents of Chilean strawberry fruit via thermogravimetric analysis (TGA) combined with analyses of mRNA abundance, enzymatic activity, and physiological characteristics. The results showed that the thermal stability was lower in the ripe stage sample than in the other two samples, while the first derivative of the thermogram (DTG) curve described four maximum peaks of degradation, between 175 and 375 °C. The percentage cumulative depolymerization (PCD) was higher in the ripe samples, and the PCD value of 325° C, where 51.65% of the carbohydrate polymers present in the cell wall have been depolymerized, was highlighted. Finally, the existence of a relationship between the percentage of the cell wall polymer degradation and the solid soluble concentration (SSC)/firmness ratio, provides the basis for a model for understanding the changes in cell wall polymers during fruit development. [ABSTRACT FROM AUTHOR]

This work evaluated the crystallization pressure of sodium and magnesium sulphates as a tool to break down and defibrillate plant cell walls, aiming at a novel, environmentally friendly and low-cost methodology to obtain micro and nanofibrilated cellulose. Elephant grass leaves both in natura and delignified were soaked in Na2SO4 and MgSO4 solutions and oven-dried at 105 ± 3 °C to promote salt crystallization, while the damage resulted from the pressure exerted by the growing crystals within the cell walls was evaluated. Na2SO4 crystallization proved to be more effective to unpack and defibrillate cell walls in comparison to MgSO4. In addition, both salts had more noticeable effects in previously delignified samples than in in natura samples. Nanofibrillated cellulose was obtained by Na2SO4 action and after shearing fibres treated with an aqueous MgSO4 solution (30% w/v), glycerol and NaOH (5% w/v). [ABSTRACT FROM AUTHOR]

Lately, cocoa pod husk (CPH) has received some attention from researchers due to its significant content of cellulose, hemicelluloses and pectin, antioxidant capacity, potential for energy generation, physicochemical characteristics and possibility to be used as adsorbent material or activated carbon. In this work, alkaline (NaOH 2.3% w/v) and enzymatic treatment [Cellic® CTec 2 (2.4% v/v)] were developed before propionic acid (PA) production using fermentable sugars derived from cocoa pod husk hydrolysate (CPHH). The physical, structural and morphological characteristics of raw and treated samples of CPH lignocellulosic matrix were assessed using tools such as scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry, and X-ray diffraction. The results of these analyses revealed the effectiveness of CPH sequential alkaline and enzymatic treatment for glucose production, reaching maximum concentration of 60.5 g·L−1 and a yield of 275 mg glucose·g−1 CPH. Subsequently, a medium composed by glucose from CPHH (7.5 g·L−1), as low-cost feedstock, glycerol (7.5 g·L−1) and yeast extract (10 g·L−1), was prepared to obtain PA using Propionibacterium jensenii DSM 20274. PA concentration reached a maximum of 10.28 ± 1.05 g·L−1 and a productivity of 0.08 ± 0.01 g·L−1·h−1 after 72 h of fermentation. To the best of our knowledge, there is no literature available on the bioconversion of CPH for the specific production of PA or other organic acids. Thus, the potential of CPH to be used as substrate for PA production was demonstrated with good perspectives. [ABSTRACT FROM AUTHOR]

Enzymatic cleavage of glycocidic bonds is an important, green and biocompatible means to refine lignocellulosic biomass. Here, the effect of the resulting oxidation point defects on the structural and water interactions of crystalline cellulose {100} surface are explored using classical molecular dynamics simulations. We show that even single oxidations reduce the connections within cellulose crystal significantly, mostly via local interactions between the chains along the surface plane but also via the oxidation defects changing the structure of the crystal in direction perpendicular to the surface. Hydrogen bonding on the surface plane of cellulose is analyzed to identify onset of desorption of glucose chains, and the desorption probed. To assess the actual soluble product profile and their fractions resulting from lytic polysaccharide monooxygenase (LPMO) enzyme oxidation on real cellulose crystal samples, we employ High-Performance Anion-Exchange Chromatography with Pulsed Amperometric-Detection (HPAEC-PAD) technique. The findings demonstrate the LPMO oxidation results in soluble glucose fragments ranging from 2 to 8 glucose units in length. Additionally, significantly more oxidized oligosaccharides were released in LPMO treatment of AaltoCell than Avicel, the two studied microcrystalline cellulose species. This is likely to result from the large reactive surface area preserved in AaltoCell due to manufacturing process. Furthermore, as can be expected, the oxidation defects at the surfaces lead to the surfaces binding a larger amount of water both via direct influence by the defect but also the defect induced protrusions and fluctuations of the glucose chain. We quantify the enhancement of water interactions of cellulose crystals due to the oxidation defects, even when no desorption takes place. The molecular simulations indicate that the effect is most pronounced for the C1-acid oxidation (carboxylic acid formation) but present also for the other defects resulting from oxidation. The findings bear significance in understanding the effects of enzymatic oxidation on cellulose nanocrystals, the difference between cellulose species, and cleavage of soluble products from the cellulosic material. [ABSTRACT FROM AUTHOR]

The interaction of xylan, an abundant plant polysaccharide, with cellulose microfibrils is essential for secondary cell wall strength. A deeper understanding of these interactions is crucial both to improve our understanding of plant cell wall architecture and to design alternate strategies to overcome cellulose recalcitrance for the production of biofuels and sustainable biomaterials. Naturally occurring acetate or glucuronic acid substitutions on xylan have been shown to influence xylan-cellulose interactions. Here, we use unrestrained molecular dynamics simulations to determine the interactions with the (110) hydrophilic face of cellulose fibers of four different xylans. In the absence of cellulose, all xylans, independent of the substitution pattern, adopt a highly flexible threefold helical screw conformation. However, when xylan is spatially close to a cellulose surface 1,2 linked acetyl xylans (2AcX) adopt rigid twofold helical screw conformations. The 2AcX conformations are primarily stabilized by interactions between the acetylated oxygen and the glycosidic linkage with C-O6 of cellulose. In contrast, the glycosidic oxygens and acetyl decorations for 1,3 linked acetyl groups (3AcX) are oriented away from the cellulose surface and the 3AcX xylans maintain threefold helical screw conformations on the cellulose surface. Our results show that evenly spaced chemical functionalization (with acetyl groups) and the position of substitution (1,2) on xylan backbone play key roles in tuning the xylan-cellulose interactions to stabilize the twofold helical screw conformations of xylan on the cellulose surface. A comparison with previous experimental findings further suggests that 1,2 substitutions induce twofold helical screw conformations of xylan on the cellulose surface irrespective of the chemical nature of the substituent, while 1,3 substitutions primarily bind lignin in threefold helical screw conformations rather than cellulose in plant cell walls. [ABSTRACT FROM AUTHOR]

EG1 from Volvariella volvacea is a processive endoglucanase belonging to glycoside hydrolase family 5. The impacts of cotton linter pulp characteristics, such as degree of polymerization (DP), crystallinity, and the initial cellulose-reducing ends, on the processivity of EG1 were investigated. Three commercial cotton linter pulp with different DP were used in present study. Ball milling was used to alter the crystallinity and DP of cellulose. The results indicate that the crystallinity has the most significant impact on enzyme processivity followed by initial cellulose-reducing ends. Whereas the DP indirectly affects the enzymatic hydrolysis and influenced by the pulp preparation method and conditions. The initial cellulose-reducing ends also affect enzyme adsorption but their impact is not obvious when the crystallinity is very low. These results also demonstrate the endo- and exo-action are both exist for EG1. The processive exo-action can start from the newly created cellulose-reducing ends by endo-action as well as the initial cellulose-reducing ends. The contribution of initial cellulose-reducing ends is affected by its quantity and cellulose crystallinity. A plausible action mode for EG1 is also proposed. [ABSTRACT FROM AUTHOR]

Cellulose is the most abundant polysaccharide on Earth. It can be obtained from a vast number of sources, e.g. cell walls of wood and plants, some species of bacteria, and algae, as well as tunicates, which are the only known cellulose-containing animals. This inherent abundance naturally paves the way for discovering new applications for this versatile material. This review provides an extensive survey on cellulose and its derivatives, their structural and biochemical properties, with an overview of applications in tissue engineering, wound dressing, and drug delivery systems. Based on the available means of selecting the physical features, dimensions, and shapes, cellulose exists in the morphological forms of fiber, microfibril/nanofibril, and micro/nanocrystalline cellulose. These different cellulosic particle types arise due to the inherent diversity among the source of organic materials or due to the specific conditions of biosynthesis and processing that determine the consequent geometry and dimension of cellulosic particles. These different cellulosic particles, as building blocks, produce materials of different microstructures and properties, which are needed for numerous biomedical applications. Despite having great potential for applications in various fields, the extensive use of cellulose has been mainly limited to industrial use, with less early interest towards the biomedical field. Therefore, this review highlights recent developments in the preparation methods of cellulose and its derivatives that create novel properties benefiting appropriate biomedical applications. [ABSTRACT FROM AUTHOR]

The decrease in crystallinity of a cotton thread upon exposure to the ionic liquid 1-ethyl-3-methylimidazolium acetate is investigated via two-dimensional Raman spectral mapping of the thread cross-section. By monitoring an intrinsic cellulose I Raman mode, the transition from highly crystalline cellulose I to amorphous cellulose is monitored as a function of treatment time and temperature. At extended treatment times, a heterogeneous decrystallization occurs where only those fibers at the outer edge of the thread decrystallize and dissolve while fibers in the thread center exhibit a constant crystallinity. As a result, a large amorphous cellulose shell develops which surrounds a central bundle of still-distinct and highly crystalline cotton fibers. Observed trends in the temperature-dependent rate of heterogeneous thread decrystallization are attributed to a transition to diffusion-limited decrystallization associated with the development of a solvent-swollen amorphous polymer layer. Raman spectral mapping provides new opportunities to investigate the effect of treatment conditions on the spatial extent and degree of crystallinity as well as the mechanism of decrystallization in cellulose biopolymer materials. [ABSTRACT FROM AUTHOR]

A kind of lignin-rich microcrystalline cellulose (MCC) with short rod structure was successfully prepared from spruce chemithermomechanical pulp (CTMP) fibers via Fe3+ enhanced high temperature liquid water (HTLW) treatment process. During this process, hemicelluloses were selectively removed, while lignin and cellulose were partially dissolved. The α-cellulose content of as-prepared MCC specimens increased significantly. XRD analysis indicated that the MCC specimens exhibited higher crystallization index than original specimen and was cellulose I type. GPC and 2D NMR analyses indicated that lignin suffered strengthened depolymerization and condensation effects under the catalytic effect of Fe3+ during treatment process. These resulted in the decreased molecular weight and polydispersity index (PDI), also hindered the further dissolution of lignin component from as-prepared MCC specimens. A relatively small repose angle indicated that the as-prepared MCC exhibited a desirable fluidity comparable to the commercial MCC product. TG analysis also showed that MCC specimens exhibited better thermal stability than commercial MCC product, which might be used as a filler to enhance the thermal performance of composites. Besides, this kind of lignin-rich MCC is also expected to be used in the field of medicinal food aid and feed additive. [ABSTRACT FROM AUTHOR]

Particle size measurements of cellulose nanocrystals (CNCs) are challenging due to their broad size distribution, irregular shape and propensity to agglomerate. Particle size is one of the key parameters that must be measured for quality control purposes and to differentiate materials with different properties. We report the results of an interlaboratory comparison (ILC) which examined atomic force microscopy (AFM) data acquisition and data analysis protocols. Samples of CNCs deposited on poly-L-lysine coated mica were prepared in the pilot laboratory and sent to 10 participating laboratories including academic, government and industrial organizations with varying levels of experience with imaging CNCs. The participant data sets indicated that the central location, width and asymmetry varied considerably for both length and height distributions. To deal with this variability we used a skew normal distribution to model the data from each laboratory and to obtain the consensus distribution that describes the CNC particle size. The skew normal distribution has 3 parameters: a central location (mean), distribution width (standard deviation) and asymmetry (shape) factor. This approach gave consensus distributions with mean, standard deviation and asymmetry factor of 94.9 nm, 37.3 nm and 6.0 for length and 3.4 nm, 1.2 nm and 2.8 for height, respectively. The use of multiple probes and/or deterioration of the probe with increased use are significant contributing factors to the variability in mean length between laboratories. There is less variability in height across participating laboratories and tests of applied imaging force indicate that it is possible to image without significant compression of the CNCs. The number of CNCs necessary to obtain a reliable data set depends on the probes and operating conditions, but with careful control of various parameters analysis of 250 and 300 CNCs should provide consistent data sets for height and length, respectively for one sample. Comparison of AFM with transmission electron microscopy (TEM) data obtained in the same ILC demonstrated excellent agreement between measured lengths for the 2 methods. By contrast AFM height was approximately one half the TEM width, a result that indicates the presence of a significant number of laterally agglomerated particles, consistent with literature data. [ABSTRACT FROM AUTHOR]

Properties of cellulose nanocrystals (CNCs) depend upon their supramolecular structures, which are important to understand in order to optimize their applications. In this investigation, the structures of CNCs produced upon 48–64% H2SO4 hydrolysis of hydrothermally-treated poplar, bleached kraft pulp, cotton microcrystalline cellulose, bacterial cellulose, tunicin, and cladophora cellulose were comparatively analyzed. TEM provided information on the morphological aspects. Raman, MAS-NMR, and XRD provided information on one aspect of the supramolecular organization, namely, crystallinity (CrI). Other characteristics of supramolecular structure were analyzed by various Raman methods, namely, accessibility to water, exocyclic CH2OH conformation ratio, and chain conformation disorder (CCONDIS)—the last method was developed in the present study. In general, CNCs retained the crystallinity of the starting material irrespective of the measurement method of CrI. Additionally, it was found that crystallite size and supramolecular organization influenced CrI as well. These analyses further indicated that poplar- and pulp-CNCs had significantly higher water accessibility as compared with CNCs from cladophora, bacterial, tunicin, and cotton MCC CNCs, implying higher molecular disorder, which was also reflected in measurements of CH2OH conformation ratio and CCONDIS. The findings indicate that significant differences among the CNCs seem to arise largely from differences between the starting materials. Additionally, considering that CNCs can have very different morphologies and structural properties depending upon how they are produced, the analyses carried out here can characterize such CNCs and estimate their applications. [ABSTRACT FROM AUTHOR]

Cellulose nanofibrils (CNFs) produced through processes involving oxidation (e.g. TEMPO oxidation) present reactive groups that allow for straightforward modification in aqueous suspension. CNFs fabricated through mechanical refinement alone can be challenging to modify for subsequent reactions due to only having hydroxyl groups present on the surface. To address these issues, CNFs with only hydroxyl groups present were functionalized with norbornene groups in their native aqueous suspension to achieve up to 10% functionalization per anhydroglucose unit. Since quantification of surface functionalization of CNFs is challenging through most methods, a degradation and subsequent nuclear magnetic resonance analysis method was developed to quantify norbornene functionalization. The norbornene functionalized CNFs (nCNFs) were cross-linked through UV and thermally initiated thiol-ene click reactions to create robust CNF hydrogels. By varying the reaction conditions, hydrogels made from nCNFs and a dithiol cross-linker could achieve compression modulus values up to 25 kPa. The materials were stable in aqueous suspensions and the cross-linked hydrogels still exhibited shear thinning behavior with high recovery, which demonstrated that even though effective cross-links were formed, a complete network was not. Through this study, thiol-norbornene crosslinking of CNFs could create robust hydrogels and improve aqueous stability that could have applications in sustainable materials and biomaterials. [ABSTRACT FROM AUTHOR]

Cellulose nanofibrils (CNFs) are top-down nanomaterials obtainable from abundant lignocelluloses. Despite recent advances in processing technologies, the effects of variations in the lignocellulose structure and composition on CNF isolation and properties are poorly understood. In this study, we compared the isolation of CNFs from tension wood (TW) and normal wood (NW) from Populus tremula (aspen). The TW has a higher cellulose content, native cellulose fibrils with a larger crystalline diameter, and less lignin than the NW, making it an interesting material for CNF isolation. The wood powders were oxidized directly by 2,2,6,6-tetramethylpiperidin-1-oxyl, and the morphology and mechanical behaviors of the nanofibril suspensions and networks were characterized. The TW was more difficult to fibrillate by both chemical and mechanical means. Larger nanofibrils (5–10 nm) composed of 1.2 nm structures were present in the TW CNFs, whereas the NW samples contained more of thin (1.6 nm) structures, which also comprised 77% of the solid yield compared to the 33% for TW. This difference was reflected in the TW CNF networks as decreased transmittance (15% vs. 50%), higher degree of crystallinity (85.9% vs. 78.0%), doubled toughness (11 MJ/m3) and higher elongation at break (12%) compared to NW. The difference was ascribed to greater preservation of the hierarchical, more crystalline microfibril structure, combined with a more cellulose-rich network (84% vs. 70%). This knowledge of the processing, structure, and properties of CNFs can facilitate the breeding and design of wood feedstocks to meet the increasing demand for nanoscale renewable materials. [ABSTRACT FROM AUTHOR]

The morphological features of raw ramie and the distribution of polysaccharides on such features were investigated using various microscopes to reveal the pivotal factors that influence microbial degumming efficiency. Results indicated that the morphological features mainly included fence, chunk, membrane, ribbon, and plank shapes. The various morphological features had their respective coverage characteristics. The fence and chunk shapes distributed on the membrane shape and cemented the fiber bundle. The ribbon shape was covered by the plank shape in several locations, and they covered one lateral surface of the fiber bundle as an integral. All of these morphological features were not observed in the refined fiber, indicating these features belonged to gum that consists of non-cellulosic components traditionally. However, some cellulose was also found in these features and should be classified as a new kind of gum component because this part of cellulose was not used for weaving. Apart from cellulose, the membrane shape contained mannan and xylan, and the fence and chunk shapes contained pectin, but the ribbon and plank shapes contained three of them. What's more, the xylan on the membrane and ribbon shapes was masked by several components, and the mannan on the membrane and plank shapes was also masked. Furthermore, the coverage characteristics of the morphological features and the masking relationship (cross-linking) among polysaccharides influenced the contact degree between the enzyme and gum and further degumming efficiency. Increasing the contact degree between the enzyme and gum is a pivotal factor for improving degumming efficiency. [ABSTRACT FROM AUTHOR]

Phenol, considered as a stable and refractory organic pollutant, has posed an increasing threat to the environment and human health. Herein, the ZnO was regulated with nano-biochar (CCNC) derived from cellulose nanocrystals (CNCs). The CCNC/ZnO photocatalysts were fabricated via in situ precipitation and carbonization, in which CNCs served as both the templates and carbon source. Meanwhile, Zn2+ ions deposited on the surface of rod-like CNCs by electrostatic interaction. Subsequently, homogeneous dispersed ZnO nanoparticles were anchored onto the surface of CNCs, decreasing the ZnO nanoparticles size. As the CNCs transformed into CCNC, the resultant CCNC/ZnO photocatalysts demonstrated excellent degradation efficiency to phenol, corresponding to 99.8% within 90 min. Additionally, the CCNC/ZnO photocatalysts also displayed a satisfactory stability for five cycles without significant performance being decreased. The calculating and experimental results demonstrated that the conjugated graphitic structures of CCNC effectively reduced the band gap of ZnO from 3.26 to 2.96 eV. Besides, the CCNC remarkably promoted photogenerated electron-hole pairs separation and transfer, thereby improving the photodegradation efficiency for phenol. Furthermore, the efficiency for phenol photodegradation was comprehensively influenced by a combination of the ratio of photocatalyst, initial phenol concentration and catalyst dose, and pH value. This study broadened the application of CNCs in the field of photocatalysis, which provided a new perspective for the preparation of highly efficient photocatalysts using CNCs derived nano-biochar as a template and charge-transport pathway. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) is a biodegradable polymer that benefits in purity, crystallinity and superior optical, structural and mechanical properties. Such properties facilitate BC to replace the conventional non-biodegradable materials used, for instance, in sensing applications. However, BC production is largely conducted in conventional medium containing model substrates and complex carbon-containing compounds. Aiming towards the production of eco-friendly piezoelectric-responsive BC films, we isolated and characterized a novel bacterial strain affiliated to Komagataeibacter rhaeticus. The K. rhaeticus ENS9a strain synthesized BC in minimal medium containing crude glycerol, generating a titer of 2.9 ± 0.3 g/L BC. This is, to the best of our knowledge, the highest BC titer reported from an unoptimized minimal medium containing crude glycerol. Interestingly, the films prepared from crude glycerol showed normal force and bending mode sensitivities of 6–11 pC/N and 40–71 pC/N, respectively, demonstrating a green platform to address both bioprocess waste valorization and implementation of cellulose-based alternatives for the non-sustainable and non-biodegradable materials, such as fluoropolymers or lead containing piezoceramics, used in sensing applications. In silico genome analysis predicted genes partaking in carbohydrate metabolism, BC biogenesis, and nitrogen fixation/regulation. [ABSTRACT FROM AUTHOR]

This work proposes the application of di-carboxylic acid cellulose nanofibril (DCA-CNF) obtained through maleic acid hydrolysis as an additive in water-based drilling fluids (WBMs). Specifically, the use of DCA-CNF as a replacement of xanthan gum (XGD) in the WBM formulations was evaluated. The effect of DCA-CNF on the main functional properties of WBMs and their performance was evaluated and compared with that corresponding to XGD. To this end, interactions between DCA-CNF and bentonite (BT), as well as between DCA-CNF and polyanionic cellulose (PAC), were studied using quartz crystal microbalance with dissipation monitoring (QCM-D) technique. The rheological analyses showed a shear-thinning behavior of WBMs containing XGD similar to WBMs with DCA-CNF, while filtration properties and thermal stability improved by the presence of DCA-CNF. Results obtained by QCM-D indicated higher interaction between PAC and DCA-CNFs when compared to BT and DCA-CNF. The Sisko model was implemented to simulate the relationship between viscosity and shear rate. WBM for Argentina shale containing the double concentration of DCA-CNF exhibited similar rheological properties to the base fluid. [ABSTRACT FROM AUTHOR]

The performance of cellulosic materials is intimately linked to their moisture content. Over the last century, many studies have been devoted to examining the moisture uptake in equilibrium with surrounding environmental conditions. However, with the adoption of automated sorption balances in laboratories worldwide, it has become increasingly popular to study the approach to equilibrium, i.e., sorption kinetics. Recording the moisture content change between two equilibrium states produces a wealth of data, which necessitates a robust methodology for analysis. In this study, we employ exponential decay analysis on sorption kinetic data obtained in a previous study for loblolly pine, holocellulose, office paper and microcrystalline cellulose. Unlike other methods that are constrained by a fixed number of fitting parameters or similar constraints, exponential decay analysis is a flexible, data-driven methodology for analyzing sorption kinetics. No physical meaning is assigned to the output from the analysis. However, the methodology yields robust results in relation to various measurement uncertainties. As a result, exponential decay analysis can provide a reliable description of the dominant time scales of sorption kinetics. Hereby, the methodology offers a new way to evaluate the suitability of theoretical models for describing sorption kinetics. [ABSTRACT FROM AUTHOR]

Due to biomass recalcitrance, the pulping and bleaching processes are usually needed to break down the resistance of the lignocellulosic matrix for nanocellulose extraction. In this study, an acidic deep eutectic solvent (DES) based on choline chloride-oxalic acid dihydrate was used to directly pretreat raw ramie fibers (RFs) without further bleaching/purification steps for producing cellulose nanomaterials. Raw RFs, DES pretreated RFs, and degummed RFs were comparatively studied as starting materials for the preparation of cellulose nanofibrils (CNFs) by ball milling. There was no significant difference between CNF samples prepared from the DES pretreated RFs after 6 h of ball milling and those from the degummed RFs after 12 h of ball milling. After 4 h DES pretreatment at 100 °C, the obtained CNFs had a high purity of glucan up to 90.31% and an average width of 14.29 nm. They also showed high crystallinity (79.17%) and high thermal stability (> 316.7 °C). The tensile strength and elastic modulus for the CNF films were 98.071 MPa and 2.749 GPa, respectively. Overall, with the choline chloride-oxalic acid dihydrate DES pretreatment, no additional pulping/bleaching processes were required for the preparation of nanocellulose from raw cellulosic fibers while the properties of the as-prepared nanocellulose were preserved. [ABSTRACT FROM AUTHOR]

In the present study, a suspension of nanofibrillated cellulose from eucalyptus was spray-dried in order to obtain a powdered material that could be easily transported and stored. The original suspension and the dried material were characterized for their physical, morphological and thermal properties. An increase in crystallinity and reduction in thermal stability were observed after drying. In addition, the fibrils size passed from nano to micro scale The powder obtained was rehydrated and homogenized by two methods: rotor-stator homogenization (5000, 10,000 and 15,000 rpm) and ultrasound (10, 30 and 50% maximum amplitude), during 3 and 5 min, in order to verify the possibility of obtaining a stable reconstituted suspension comparable to the original one. Higher treatment intensities resulted in suspensions with higher viscosity and stability. The suspension homogenized by ultrasound at 50% amplitude for 5 minutes was the most stable one and restored the nano dimensions of the original suspension. Both the original and the reconstituted suspensions showed a shear thinning and "gel-like" behavior. Higher Ultra-Turrax speed and ultrasound amplitude resulted in higher viscoelastic modulus (G′ and G″), although these values were lower than those found in the initial nanocellulose suspension. [ABSTRACT FROM AUTHOR]

Nanofibrillated cellulose (NFC) extracted from biomass has potential applications in material science and biomedical engineering. In this study, NFC was obtained from bleached eucalyptus Kraft pulp (BEKP) using two commercial enzyme cocktails with cellulolytic and hemicellulolytic activities and non-catalytic protein (swollenin), followed by ultrasonication. This work represents an initial study of the implementation of non-catalytic proteins along with enzymes to extract NFC from biomass. Enzymatic pretreatment was performed to partially remove hemicellulose while enhancing cellulose accessibility for NFC extraction. Cellulase pretreatment with xylanase and swollenin supplementation increased cellulose accessibility and fiber swelling due to extensive hemicellulose removal (> 80%) and fiber morphology changes. Subsequent ultrasonication was performed for cellulose nanofibrillation resulting in high NFC yields (61–97%), while keeping NFC properties almost unchanged. Through this process, cellulose nanofibers with diameters ranging from 3 nm to 10 nm were effectively isolated from BEKP, which allows to produce high quality NFC for further applications. [ABSTRACT FROM AUTHOR]

Processing of lignocellulosic biomass is complex due to the heterogeneity of the substrate, but also due to lengthy unit operations, which complicates process control including for enzymatic saccharification. Methods for predicting enzymatic saccharification yield based on the properties of the pretreated biomass would be advantageous to process optimization and control. Biomass-water interaction measurements provide a method for quickly predicting biomass recalcitrance. Correlating water retention value (WRV) and enzymatic saccharification yield (ESY) on pretreated biomass has shown promise, especially when assessing only single biomass types pretreated with one specific chemistry. However, with comparisons between different types of biomasses, predictive powers have been low. We investigate the effect of pretreatment chemistry on the predictive power of WRV, when keeping the biomass static. Wheat straw was pretreated with dilute acid, hydrothermal, or alkaline chemistries at five different temperatures. Furthermore, low field nuclear magnetic resonance was used to measure water constraint in the pretreated materials, to better understand how biomass-water interactions change with pretreatment severity and chemistry. We show that the correlation of WRV and ESY is highly pretreatment dependent, while WRV strongly predicts ESY within each pretreatment chemistry. While ESY and WRV correlated under all chemistries, the direction of the correlations were divergent, suggesting a more complex interplay between recalcitrance and biomass-water interactions. Using T2 relaxation profiles, reductions in hemicellulose composition was related to the decrease in size of the most constrained water population present in the pretreated biomasses for all chemistries, suggesting a new identification of this population of constrained water. [ABSTRACT FROM AUTHOR]

This work proposes the application of di-carboxylic acid cellulose nanofibril (DCA-CNF) obtained through maleic acid hydrolysis as an additive in water-based drilling fluids (WBMs). Specifically, the use of DCA-CNF as a replacement of xanthan gum (XGD) in the WBM formulations was evaluated. The effect of DCA-CNF on the main functional properties of WBMs and their performance was evaluated and compared with that corresponding to XGD. To this end, interactions between DCA-CNF and bentonite (BT), as well as between DCA-CNF and polyanionic cellulose (PAC), were studied using quartz crystal microbalance with dissipation monitoring (QCM-D) technique. The rheological analyses showed a shear-thinning behavior of WBMs containing XGD similar to WBMs with DCA-CNF, while filtration properties and thermal stability improved by the presence of DCA-CNF. Results obtained by QCM-D indicated higher interaction between PAC and DCA-CNFs when compared to BT and DCA-CNF. The Sisko model was implemented to simulate the relationship between viscosity and shear rate. WBM for Argentina shale containing the double concentration of DCA-CNF exhibited similar rheological properties to the base fluid. [ABSTRACT FROM AUTHOR]

The increasing interest for cellulose-based products has resulted in the development of processes for the controlled deconstruction of cellulose into cellulose nanomaterials, such as cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). These nanomaterials can significantly increase the diverse applications of cellulose by exploring their nanometric scale options and improved properties for various high-volume, low-volume, and emerging/novel applications. Among the nanocellulose production processes, the enzyme-mediated methods are environment friendly and with expected lower capital and operating expenditures compared to traditional processes. In addition, it creates the unique possibility of fine-tuning the process to tailor nanocellulose properties that are suitable for specific applications. This review comprehensively examines the application of enzymes in the isolation of nanocelluloses. To date, no enzyme preparation for application to nanocellulose production is available commercially. Therefore, a fundamental understanding of potential enzymes focusing mainly on their differentiated properties, mechanism and alterations promoted to cellulose at different levels is first provided. This is to shed light on the enzyme properties that can be exploited for application in nanocellulose isolation. Then, the current state of the stand-alone and integrated enzyme-mediated processes is reviewed as well as the properties and yield of the isolated nanocelluloses in comparison to nanocelluloses obtained by traditional processes. In addition, the potential of enzyme-mediated functionalization has been discussed as a promising method that imparts unique properties to nanocelluloses, further diversifying their market. A detailed discussion on the challenges and opportunities for the major technical and economic factors that impact nanocellulose price has been included as well. [ABSTRACT FROM AUTHOR]