Showing papers on "Cellulose published in 2016"
TL;DR: A review of cellulose nanofibrillated cellulose (CNF) is presented in this article, covering raw materials selection, structural and chemical aspects, conventional and novel mechanical disintegration techniques, as well as biological and chemical pretreatments aimed at facilitating Nanofibril isolation.
1,071 citations
TL;DR: This paper reports that adding formaldehyde during biomass pretreatment produces a soluble lignin fraction that can be converted to guaiacyl and syringyl monomers at near theoretical yields during subsequent hydrogenolysis, three to seven times those obtained without formaldehyde.
Abstract: Practical, high-yield lignin depolymerization methods could greatly increase biorefinery productivity and profitability. However, development of these methods is limited by the presence of interunit carbon-carbon bonds within native lignin, and further by formation of such linkages during lignin extraction. We report that adding formaldehyde during biomass pretreatment produces a soluble lignin fraction that can be converted to guaiacyl and syringyl monomers at near theoretical yields during subsequent hydrogenolysis (47 mole % of Klason lignin for beech and 78 mole % for a high-syringyl transgenic poplar). These yields were three to seven times those obtained without formaldehyde, which prevented lignin condensation by forming 1,3-dioxane structures with lignin side-chain hydroxyl groups. By depolymerizing cellulose, hemicelluloses, and lignin separately, monomer yields were between 76 and 90 mole % for these three major biomass fractions.
860 citations
TL;DR: In this paper, the widely used non-derivatizing cellulose solvents are summarized, including their dissolution mechanisms, with emphasis on the neat regenerated cellulose materials and the composite materials.
710 citations
TL;DR: Objectives of this review were to update and extend previous works on pretreatment of lignocellulosic biomass for biofuels and biochemicals using organic solvents, especially on ethanol, methanol, ethylene glycol, glycerol, acetic acid, and formic acid.
574 citations
TL;DR: In this article, a review of the recent developments of the processing of cellulose nanocomposites focusing on the most used techniques, including solution casting, melt-processing of thermoplastic cell...
Abstract: This review addresses the recent developments of the, processing of cellulose nanocomposites, focusing on the most used techniques, including solution casting, melt-processing of thermoplastic cell ...
547 citations
TL;DR: This review focuses on the utilization of cellulose as an adsorbent in natural/modified form or as a precursor for activated carbon (AC) for adsorbing substances from water and reports a few controversies and unresolved questions concerning the preparation/properties of ACs from cellulose.
529 citations
TL;DR: The design parameters for different applications of various pure and composite hydrogels based on cellulose, chitin, or chitosan, including applications as controlled and targeted drug delivery systems, improved tissue engineering scaffolds, wound dressings, water purification sorbents, and others are compared.
473 citations
444 citations
TL;DR: In this paper, the authors reported the production of highly thermal stable and functional cellulose nanocrystals (CNC) and nanofibrils (CNF) by hydrolysis using concentrated organic acids.
387 citations
TL;DR: This review summarises properties and preparation procedure of chitosan-cellulose blends and nano size cellulose reinforcement in ch itosan bionanocomposites for different applications.
378 citations
TL;DR: The construction of double‐cross‐linked (DC) cellulose hydrogels is described using sequential chemical and physical cross‐linking, resulting in DC celluloseHydrogels that are mechanically superior to single‐ cross‐linked cellulosehydrogels.
Abstract: Polysaccharide-based hydrogels have multiple advantages because of their inherent biocompatibility, biodegradability, and non-toxicic properties. The feasibility of using polysaccharide-based hydrogels could be improved if they could simultaneously fulfill the mechanical property and cell compatibility requirements for practical applications. Herein, the construction of double-cross-linked (DC) cellulose hydrogels is described using sequential chemical and physical cross-linking, resulting in DC cellulose hydrogels that are mechanically superior to single-cross-linked cellulose hydrogels. The formation and spatial distribution of chemically cross-linked domains and physically cross-linked domains within the DC cellulose hydrogels are demonstrated. The molar ratio of epichlorohydrin to anhydroglucose units of cellulose and the concentration of the aqueous ethanol solution are two critical parameters for obtaining mechanically strong and tough DC cellulose hydrogels. The mechanical properties of the DC cellulose hydrogels under loading-unloading cycles are described using compression and tension models. The possible toughening mechanism of double-cross-linking is discussed.
TL;DR: This non-experimental approach to corrosion could foster a better understanding of the corrosion inhibition processes by correlating actual inhibition mechanisms with molecular structures of these carbohydrate polymers.
TL;DR: The Segal method estimates the amorphous fraction of cellulose Iβ materials simply based on intensity in an X-ray diffraction pattern and was extended to cellulose II using 16° 2θ intensity, which resulted in relatively good agreement with the simulation for mercerized cotton.
TL;DR: Optically transparent wood with transmittance as high as 85% and haze of 71% was obtained using a delignified nanoporous wood template using refractive-index-matched prepolymerized methyl methacrylate (MMA).
TL;DR: These findings highlight the extensive and unexplored structural diversity of enzymatic systems in cellulolytic soil bacteria and indicate the roles of multiple abundant bacterial taxa in the decomposition of cellulose and other plant polysaccharides.
Abstract: Evidence shows that bacteria contribute actively to the decomposition of cellulose and hemicellulose in forest soil; however, their role in this process is still unclear. Here we performed the screening and identification of bacteria showing potential cellulolytic activity from litter and organic soil of a temperate oak forest. The genomes of three cellulolytic isolates previously described as abundant in this ecosystem were sequenced and their proteomes were characterized during the growth on plant biomass and on microcrystalline cellulose. Pedobacter and Mucilaginibacter showed complex enzymatic systems containing highly diverse carbohydrate-active enzymes for the degradation of cellulose and hemicellulose, which were functionally redundant for endoglucanases, β-glucosidases, endoxylanases, β-xylosidases, mannosidases and carbohydrate-binding modules. Luteibacter did not express any glycosyl hydrolases traditionally recognized as cellulases. Instead, cellulose decomposition was likely performed by an expressed GH23 family protein containing a cellulose-binding domain. Interestingly, the presence of plant lignocellulose as well as crystalline cellulose both trigger the production of a wide set of hydrolytic proteins including cellulases, hemicellulases and other glycosyl hydrolases. Our findings highlight the extensive and unexplored structural diversity of enzymatic systems in cellulolytic soil bacteria and indicate the roles of multiple abundant bacterial taxa in the decomposition of cellulose and other plant polysaccharides.
TL;DR: Deep eutectic solvents could be used as a promising and biocompatible pretreatment method for the conversion of lignocellulosic biomass into biofuel.
TL;DR: The present review article outlines the development history of research in the field of cellulose and chitosan, various methods employed for the functionalization of the biopolymers, current stage of research, and mechanisms involved in adsorption of heavy metals and dyes using nanocellulose and nanochitOSan.
TL;DR: It is shown that the majority of xylan flattens into a twofold helical screw ribbon to bind intimately to cellulose microfibrils in the cell wall, providing new principles to understand biomass properties.
Abstract: Exploitation of plant lignocellulosic biomass is hampered by our ignorance of the molecular basis for its properties such as strength and digestibility. Xylan, the most prevalent non-cellulosic polysaccharide, binds to cellulose microfibrils. The nature of this interaction remains unclear, despite its importance. Here we show that the majority of xylan, which forms a threefold helical screw in solution, flattens into a twofold helical screw ribbon to bind intimately to cellulose microfibrils in the cell wall. 13C solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, supported by in silico predictions of chemical shifts, shows both two- and threefold screw xylan conformations are present in fresh Arabidopsis stems. The twofold screw xylan is spatially close to cellulose, and has similar rigidity to the cellulose microfibrils, but reverts to the threefold screw conformation in the cellulose-deficient irx3 mutant. The discovery that induced polysaccharide conformation underlies cell wall assembly provides new principles to understand biomass properties.
TL;DR: The prepared nano-dimensional cellulose demonstrated a network-like structure with higher crystallinity than that of untreated fiber, and possessed of good thermal stability which is suitable for nanocomposite material.
TL;DR: In this work, nanocellulose was extracted from bleached corncob residue (CCR), an underutilized ligno cellulose waste from furfural industry, using four different methods and the intensive pulp refining led to the CNFs with the longest length and the thickest diameter.
TL;DR: In this article, a kind of cellulose-clay hydrogel with superabsorbent properties, superior mechanical performance, and high dye removal efficiency was reported, which fitted well with pseudo-second-order and Langmuir isotherm models.
Abstract: Toxic dyes have threatened human health through the consumption of polluted water, so removal of dyes from wastewater has become a hot topic in both academic and industrial fields. Herein, we reported a kind of cellulose–clay hydrogel with superabsorbent properties, superior mechanical performance, and high dye removal efficiency. The main strategy for the preparation of superabsorbent hydrogels was chemical cross-linking of cellulose, carboxymethyl cellulose (CMC), and the intercalated clay in NaOH/urea aqueous solution. The as-prepared hydrogels exhibited high absorption capacity for methylene blue (MB) solution through a spontaneous physic-sorption process which fitted well with pseudo-second-order and Langmuir isotherm models. The maximum removal efficiencies of hydrogel samples for MB solutions with concentrations of 10 mg L–1 and 100 mg L–1 were 96.6% and 98%, respectively. These results demonstrated that cellulose–clay nanocomposite hydrogels were effective adsorbents for removal of MB dyes, which ...
TL;DR: In this paper, the fundamental properties of cellulose nanocrystals (CNCs) extracted from sugarcane bagasse were compared with cellulose cellulose nifibrils (CNFs).
Abstract: This study compared the fundamental properties of cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) extracted from sugarcane bagasse. Conventional hydrolysis was used to extract CNC while ball milling was used to extract CNF. Images generated by scanning electron microscope and transmission electron microscope showed CNC was needle-like with relatively lower aspect ratio and CNF was rope-like in structure with higher aspect ratio. Fourier-transformed infrared spectra showed that the chemical composition of nanocellulose and extracted cellulose were identical and quite different from bagasse. Dynamic light scattering studies showed that CNC had uniform particle size distribution with a median size of 148 nm while CNF had a bimodal size distribution with median size 240 ± 12 nm and 10 μm. X-ray diffraction showed that the amorphous portion was removed during hydrolysis; this resulted in an increase in the crystalline portion of CNC compared to CNF. Thermal degradation of cellulose initiated at a much lower temperature, in the case of the nanocrystals while the CNF prepared by ball milling were not affected, indicating higher thermal stability.
TL;DR: In this article, the three basic components of crude biomass, cellulose, hemicellulose, and lignin are investigated to reveal their influence on the derived carbonaceous materials.
Abstract: Porous carbon materials stemming from biomass have drawn increasing interest because of their sustainable properties. Cellulose, hemicellulose, and lignin are the three basic components of crude biomass, and were investigated to reveal their influence on the derived carbonaceous materials. Huge amounts of oxygen-containing functional groups in cellulose and hemicellulose tend to be eliminated as H2O, CO2, and CO and give micropores during pyrolysis, whereas lignin contains plentiful aromatic units which are chemically inert, and thus produce nonporous carbon materials. When the KHCO3 was introduced during the pyrolysis process, the plentiful hydroxyl in cellulose and hemicellulose underwent dehydration condensation among different parent polymers, which are responsible for the formation of macroporous structure. By contrast, The β-O-4 bands in lignin experience homolysis and give rise to benzene-containing units, which finally result in carbon nanosheets. Furthermore, we demonstrated the mixture of cellul...
TL;DR: In this article, a critical review of all aspects of the dissolution of cellulose in NaOH-based aqueous solutions is presented, from the background properties of the solvent itself, to the mechanisms of the cellulose fibre swelling and dissolution, solution structure and properties and influence of additives and, finally, the properties of various materials (fibres, films, aerogels, composites and interpenetrated networks) prepared from these solutions.
Abstract: The article is a critical review of all aspects of the dissolution of cellulose in NaOH-based aqueous solutions: from the background properties of the solvent itself, to the mechanisms of cellulose fibre swelling and dissolution, solution structure and properties and influence of additives and, finally, to the properties of various materials (fibres, films, aerogels, composites and interpenetrated networks) prepared from these solutions. A historical evolution of the research on this topic is presented. The pros and cons of NaOH-based aqueous solvent for cellulose are summarised and some prospects are suggested.
TL;DR: In this article, rice straw was subjected to fungal pretreatment using Pleurotus ostreatus and Trichoderma reesei to improve its biodegradability and methane production via solid-state anaerobic digestion (SS-AD).
TL;DR: In this study microcrystalline cellulose was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation and the improved properties due to the reinforcement of TOCNs can be highly beneficial in numerous applications.
Abstract: In this study microcrystalline cellulose (MCC) was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The treated cellulose slurry was mechanically homogenized to form a transparent dispersion which consisted of individual cellulose nanofibers with uniform widths of 3-4 nm. Bio-nanocomposite films were then prepared from a polyvinyl alcohol (PVA)-chitosan (CS) polymeric blend with different TEMPO-oxidized cellulose nanofiber (TOCN) contents (0, 0.5, 1.0 and 1.5 wt %) via the solution casting method. The characterizations of pure PVA/CS and PVA/CS/TOCN films were performed in terms of field emission scanning electron microscopy (FESEM), tensile tests, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results from FESEM analysis justified that low loading levels of TOCNs were dispersed uniformly and homogeneously in the PVA-CS blend matrix. The tensile strength and thermal stability of the films were increased with the increased loading levels of TOCNs to a maximum level. The thermal study indicated a slight improvement of the thermal stability upon the reinforcement of TOCNs. As evidenced by the FTIR and XRD, PVA and CS were considered miscible and compatible owing to hydrogen bonding interaction. These analyses also revealed the good dispersion of TOCNs within the PVA/CS polymer matrix. The improved properties due to the reinforcement of TOCNs can be highly beneficial in numerous applications.
TL;DR: In this paper, catalytic fast co-pyrolysis of biomass and polyethylene (PE) was studied in a tandem micro-pyrogrolyzer using HZSM-5 as the catalyst.
TL;DR: By inhibiting cellulase-lignin binding the cellulase dosage could be reduced dramatically thereby reducing the cost of enzyme in bioethanol process, and the techniques to study these interactions have been discussed.
TL;DR: In this article, the authors explored the utilization of garlic straw residues as source for the production of cellulose nanocrystals (CNC) by acid hydrolysis (H 2 SO 4 ).
05 Feb 2016
TL;DR: In this article, the cellulose used in this study was isolated from sugarcane bagasse, and then it was hydrolyzed by 50% sulfuric acid at 40 °C for 10 minutes.
Abstract: Cellulose in nanometer range or called by nano-cellulose has attracted much attention from researchers because of its unique properties. Nanocellulose can be obtained by acid hydrolysis of cellulose. The cellulose used in this study was isolated from sugarcane bagasse, and then it was hydrolyzed by 50% sulfuric acid at 40 °C for 10 minutes. Nanocellulose has been characterized by Transmission Electron Microscope (TEM), Particle Size Analyzer (PSA), Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD). Analysis of FTIR showed that there were not a new bond which formed during the hydrolysis process. Based on the TEM analysis, nano-cellulose has a spherical morphology with an average diameter of 111 nm and a maximum distribution of 95.9 nm determined by PSA. The XRD analysis showed that the crystallinity degree of nano-cellulose was higher than cellulose in the amount of 76.01%.