Showing papers in "Bioresources in 2017"
TL;DR: In this article, a review article was prompted by a remarkable growth in the number of scientific publications dealing with the use of nanocellulose (especially nanofibrillated cellulose, cellulose nanocrystals (CNC), and bacterial cellulose (BC)) to enhance the barrier properties and other performance attributes of new generations of packaging products.
Abstract: This review article was prompted by a remarkable growth in the number of scientific publications dealing with the use of nanocellulose (especially nanofibrillated cellulose (NFC), cellulose nanocrystals (CNC), and bacterial cellulose (BC)) to enhance the barrier properties and other performance attributes of new generations of packaging products. Recent research has confirmed and extended what is known about oxygen barrier and water vapor transmission performance, strength properties, and the susceptibility of nanocellulose-based films and coatings to the presence of humidity or moisture. Recent research also points to various promising strategies to prepare ecologically-friendly packaging materials, taking advantage of nanocellulose-based layers, to compete in an arena that has long been dominated by synthetic plastics. Some promising approaches entail usage of multiple layers of different materials or additives such as waxes, high-aspect ratio nano-clays, and surface-active compounds in addition to the nanocellulose material. While various high-end applications may be achieved by chemical derivatization or grafting of the nanocellulose, the current trends in research suggest that high-volume implementation will likely incorporate water-based formulations, which may include water-based dispersions or emulsions, depending on the end-uses.
263 citations
TL;DR: In this paper, a review of recent publications dealing with the rheology of nanocellulose aqueous suspensions in the absence of matrix materials is presented, where the focus is on systems in which the cellulosic particles themselves, dependent on their morphology and the interactive forces between them, largely govern the observed rheological effects.
Abstract: The flow characteristics of dilute aqueous suspensions of cellulose nanocrystals (CNC), nanofibrillated cellulose (NFC), and related products in dilute aqueous suspensions could be of great importance for many emerging applications. This review article considers publications dealing with the rheology of nanocellulose aqueous suspensions in the absence of matrix materials. In other words, the focus is on systems in which the cellulosic particles themselves – dependent on their morphology and the interactive forces between them – largely govern the observed rheological effects. Substantial progress in understanding rheological phenomena is evident in the large volume of recent publications dealing with such issues including the effects of flow history, stratification of solid and fluid layers during testing, entanglement of nanocellulose particles, and the variation of inter-particle forces by changing the pH or salt concentrations, among other factors. Better quantification of particle shape and particle-to-particle interactions may provide advances in future understanding. Despite the very complex morphology of highly fibrillated cellulosic nanomaterials, progress is being made in understanding their rheology, which supports their usage in applications such as coating, thickening, and 3D printing.
206 citations
TL;DR: In 2010, the U.S. Department of Energy issued a report that listed lactic acid as a potential building block for the future as discussed by the authors, which can be used in a wide variety of industries such as the cosmetic, pharmaceutical, chemical, food, and, most recently, the medical industries.
Abstract: Lactic acid is a naturally occurring organic acid that can be used in a wide variety of industries, such as the cosmetic, pharmaceutical, chemical, food, and, most recently, the medical industries. It can be made by the fermentation of sugars obtained from renewable resources, which means that it is an eco-friendly product that has attracted a lot of attention in recent years. In 2010, the U.S. Department of Energy issued a report that listed lactic acid as a potential building block for the future. Bearing the importance of lactic acid in mind, this review summarizes information about lactic acid properties and applications, as well as its production and purification processes.
171 citations
TL;DR: In this article, the effects of the delignification and mercerization treatments on sugar palm fibre (SPF) for the preparation of the hydrolysis treatment to produce nanocrystalline cellulose (NCC) for reinforcement in polymer composites were examined.
Abstract: Eco-friendly composites can be prepared by substituting man-made synthetic fibres with various types of cellulosic fibres. Sugar palm-derived nanocrystalline cellulose is a potential substitute. The most important factor in determining a good nanofiller reinforcement agent that can be used in composites is the character of the nanofiller itself, which is affected during a preliminary treatment. Thus, to gain better nanofiller properties, the delignification (NaClO2 and CH3COOH) and mercerization (NaOH) treatments must be optimized. The main objective of this study was to identify the effects of the delignification and mercerization treatments on sugar palm fibre (SPF). In addition, the characteristics of the SPF for the preparation of the hydrolysis treatment to produce nanocrystalline cellulose (NCC) for reinforcement in polymer composites were examined. Sugar palm cellulose (SPC) was extracted from the SPF, and its structural composition, thermal stability, functional groups, and degree of crystallinity were determined via field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD), respectively. The density, moisture content, chemical composition, and structure of the SPC were also analysed.
155 citations
TL;DR: In this article, the solubility of four lignin samples and their acetylated forms was determined in a series of organic solvents to investigate the relationship between solubiliacity and its parameter.
Abstract: The solubility of four lignin samples and their acetylated forms was determined in a series of organic solvents to investigate the relationship between solubility and the solubility parameter. The solubility parameter of lignin samples and acetylated lignin was calculated based on the number of atoms or groups on lignin units. Lignin samples were obtained by isolating lignin from lignocellulosic bioethanol residues (Lignin 1 [L1]), isolating lignin from kraft hardwood black liquor (Lignin 2 [L2]), commercial kraft softwood lignin (Lignin 3 [L3]), and commercial soda non-wood lignin (Lignin 4 [4]). The solubility of lignin in organic solvents was not predictable due to poor correlation between the solubility of lignin and its solubility parameter. However, the solubility of lignin in an organic solvent depended on the molecular weight and the aliphatic hydroxyl number of the lignin. L2, with a lower molecular weight than other lignin samples, had the highest solubility in organic solvents, and L3, with highest aliphatic hydroxyl number, had the lowest solubility in organic solvents. All acetylated lignins were soluble in most of the organic solvents. Furthermore, the molecular weights of the soluble parts of all four lignins in ethyl acetate were found to be lower than the original lignins.
131 citations
TL;DR: In this article, a review of chemical and impregnation wood modification techniques has been presented, and some of these technologies have reached the industrial level, such as wood acetylation and wood furfurylation.
Abstract: Significant developments in the area of wood modification have been achieved during the last three decades. These developments can be attributed to increased environmental concerns, the escalating demand for a high and constant quality of wood products, and the rising prices of the durable tropical timber as well as its very limited availability, as affected by illegal logging. As a consequence, a number of wood modification techniques such as chemical and impregnation modifications or heat treatments have been introduced, and some of these technologies have reached the industrial level. This review paper deals with two successful technologies, that is, wood acetylation and wood furfurylation. It briefly discusses the advantages of the new modified products and presents in short their improved properties. Published findings indicate that chemical modification of wood, to a full or partial degree, by means of acetylation or furfurylation, offers a way to transform low durability wood species to new ‘green’ wood materials having advanced qualities and properties.
104 citations
TL;DR: In this paper, the authors investigated the difference of the properties of the bio-char derived from moso bamboo and rice husk under different pyrolysis temperatures (200 °C to 800 °C).
Abstract: Bio-char pyrolyzed from biomass waste has been notably applied in various industries due to its versatile physicochemical characteristics. This paper investigated the difference of the properties of the bio-char derived from moso bamboo and rice husk under different pyrolysis temperatures (200 °C to 800 °C). As the temperature increased, the bio-char yield for both bamboo bio-char (BC) and rice husk bio-char (RHC) decreased, while the carbon element content and fixed carbon, the value of higher heating value (HHV) and pH increased for both BC and RHC. At 800 °C, BC had a higher HHV of 32.78 MJ/kg than RHC of 19.22 MJ/kg, while RHC had a higher yield of char (42.99 wt.%) than BC (26.3 wt.%) because of the higher ash content (47.51 wt.%) in RHC. SiO2 was the dominant component in the ash of RHC, accounting for 86.26 wt.%. The surface area (SBET) of RHC (331.23 m2/g) was higher than BC (259.89 m2/g). However, the graphitization degree of BC was higher than RHC at the same temperature. The systematic study on the evolution of the basic properties of BC and RHC will provide a good reference for their high value-added application.
71 citations
TL;DR: Inadequate rheological properties of gelatin methacrylamide were successfully improved by incorporating cellulose nanofibers (CNFs), such that the printed scaffolds could maintain their structural fidelity during the three-dimensional (3D) bio-printing process.
Abstract: Inadequate rheological properties of gelatin methacrylamide (GelMA) were successfully improved by incorporating cellulose nanofibers (CNFs), such that the printed scaffolds could maintain their structural fidelity during the three-dimensional (3D) bio-printing process. The CNFs provided an outstanding shear thinning property, and the GelMA/CNF inks exhibited high zero shear viscosity and structural fidelity under a low dispensing pressure. After evaluating the printability, composite inks containing 2% w/v CNF were observed to have an optimal concentration of CNF to prepare 3D print stable constructs. Therefore, these inks were used to manufacture human nose and ear structures, producing highly porous structures in the printed composite hydrogels. Furthermore, the mechanical stability of the GelMA/CNF composite hydrogel was increased when CNFs were incorporated, which indicated that CNFs played an important role in enhancing the structural properties of the composite hydrogels. Additionally, the biocompatibility of CNF-reinforced hydrogels was evaluated using a fibroblast cell line.
70 citations
TL;DR: In this article, the effect of drying on the strength development and adhesion between cellulose nanofibrils and wood particles was investigated, and the effects of surface roughness on the wood-CNF bonding strength was evaluated through lap shear testing and scanning electron microscopy.
Abstract: Cellulose nanofibrils (CNF) were investigated as a binder in the formulation of particleboard (PB) panels. The panels were produced in four different groups of target densities with varying amounts of CNF binder. The produced panels were then tested to determine the modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), water absorption (WA), and thickness swelling (TS) properties. Density gradients through the thickness of the panels were evaluated using an X-ray density profiler. The effect of drying on the strength development and adhesion between CNF and wood particles (WP) was investigated, and the effect of surface roughness on the wood-CNF bonding strength was evaluated through lap shear testing and scanning electron microscopy. It was found that at lower panel densities, the produced samples met the minimum standard values recommended for particleboard panels. Medium-density panels met the standard levels for IB, but they did not reach the recommended values for MOR and MOE. The possible bonding mechanism and panel formation process are discussed in light of microscopic observations and the results of lap shear tests were presented.
61 citations
TL;DR: In this paper, the authors present a review of hot-pressed bio-based board manufacturing with lignocellulosic materials, showing that the most promising technologies for environmentally friendly production of board with use of lignosic material tend to be those that favor success in the development of at least three of the mechanistic links in the hypothetical chain.
Abstract: The production of fiberboard, particleboard, and related hot-pressed biomass products can convert small, relatively low-valued pieces of wood into valuable products. There is strong interest in being able to manufacture such products without the addition of formaldehyde, which is a health hazard during both production and use. This article reviews literature describing various challenges that need to be faced in order to achieve satisfactory bonding properties in hot-pressed bio-based board products without the addition of formaldehyde. Bonding mechanisms are examined in the form of a hypothesis, in which the strength development is represented by a chain with four links. Failure of a board is expected to occur at the weakest of these mechanistic links, which include mechanical contact, molecular-scale wetting and contact, various chemical-based linkages, and structural integrity. The most promising technologies for environmentally friendly production of hot-pressed board with use of lignocellulosic materials tend to be those that favor success in the development of at least three of the mechanistic links in the hypothetical chain.
52 citations
TL;DR: In this article, the authors reviewed three common techniques: the physical method, the in situ chemical reduction method, and the covalent bonding method and compared the advantages and disadvantages among these three methods.
Abstract: With the improvement of living standards, the human demand for antibacterial materials has increased. Cellulose, as the most abundant polymer in the world, is natural, biodegradable, and renewable, which makes it a promising raw material for the production of antibacterial materials. Silver nanoparticles (AgNPs)-cellulose antibacterial composites exhibit good biocompatibility and antimicrobial properties. These materials are easily degraded chemically and are environmentally friendly. Therefore, the AgNPs-cellulose antibacterial composites exhibit broad utilization prospects in environmental protection, medicine, chemical catalysis, and other fields. Several methods are used to manufacture such materials. This paper reviews three common techniques: the physical method, the in situ chemical reduction method, and the covalent bonding method. The differences and relationships are identified, and the advantages and disadvantages are compared among these three methods. Lastly, the present situation and the development potential of the AgNPs-cellulose antibacterial composites are discussed in this review.
TL;DR: This review discusses different processes that are currently employed for lactic acid recovery, focusing on precipitation, solvent extraction, and separation with membranes, and advances in such recovery processes and drawbacks that limit the application of these technologies at the industrial level are presented.
Abstract: Lactic acid is an important platform chemical with a wide range of applications. Production of lactic acid by fermentation is advantageous because renewable and low cost raw materials can be used as substrates. After fermentation, the broth needs to be purified to obtain pure lactic acid for further uses. Thus, efficient downstream processes are very important because they account for 50% of the production costs. This review discusses different processes that are currently employed for lactic acid recovery, focusing on precipitation, solvent extraction, and separation with membranes. Advances in such recovery processes and drawbacks that limit the application of these technologies at the industrial level are also presented.
TL;DR: In this paper, the authors investigated the characteristics of four bamboo species: Dendrocalamus pendulus (DP), Dendrocamus asper (DA), Gigantochloa levis (GL), and Gigantchloa scortechinii (GS), and their three portions (bottom, middle and top).
Abstract: Bamboo among other plants has unique properties and massive variety. The properties of bamboo species vary between species and along their culms. The aim of this study was to investigate the characteristics of four bamboo species: Dendrocalamus pendulus (DP), Dendrocalamus asper (DA), Gigantochloa levis (GL), and Gigantochloa scortechinii (GS), and their three portions (bottom (B), middle (M), and top (T)). The number of fibre strands in vascular bundles and the single fibres extracted from every portion was studied. The distribution of fibres varied along the bamboo culms and between species. The DP species showed the highest water content and water absorption and the lowest mechanical properties. The DA species exhibited the best mechanical and physical properties. Moreover, the bottom portion of every species indicated the highest aspect ratio and tensile properties. The results indicated that before the application of bamboo culms in composite materials, the bamboo species should be characterized so that it can be utilised effectively as a renewable reinforcement in composites.
TL;DR: In this article, a meta-analysis of the main factors of degradation that belong to this phenomenon is presented, where the impact of irradiation, the role of water, oxygen, temperature, and colonization by fungi are explained.
Abstract: Wood is an abundant and renewable natural resource. Its use is promoted as a way to reduce the carbon footprint in building construction. Wood structures are degraded by their environment due to weathering. This review is a meta-analysis of the main factors of degradation that belong to this phenomenon. The impact of irradiation, the role of water, oxygen, temperature, and colonization by fungi are explained. To protect against these factors, the use of coatings is the most common solution. Since currently the trend is to maintain the grain and the natural color of the wood, the use of transparent coatings is favored. This review presents the main technologies used in clear wood coatings. The durability of this protection against weathering is approached. The whole of knowledge gathered has made it possible to begin a discussion on the multifactorial aspect of wood weathering. Schemes were created to synthesize the synergistic and antagonistic effects between the degradation factors.
TL;DR: In this article, the most commonly used pretreatment methods were acid and alkali, while ionic liquid and microwave assisted methods were used rarely, and the dominant sugars were glucose, xylose, galactose, arabinose, and mannose.
Abstract: Lignocellulosic biomass resources are renewable materials that can be converted to fermentable sugars and subsequently into ethanol. Water hyacinth (Eichhornia crassipes) is a cellulosic aquatic plant that has high carbohydrates, low lignin content, and notable reducing sugars content in its structure. Based on the literature review in the case of water hyacinth, the most frequently used pretreatment methods were acid and alkali, while ionic liquid and microwave-assisted methods were used rarely. The dominant sugars were glucose, xylose, galactose, arabinose, and mannose. Based on the findings, cellulase and S. cerevisiae were mostly used for enzymatic hydrolysis and fermentation of water hyacinth to ethanol, respectively. This review presents the recent studies in pretreatment, hydrolysis, and fermentation of water hyacinth biomass into ethanol.
TL;DR: In this article, the pore volume of activated carbon was shown to increase to 2192 m2/g and 1.269 cm3/g under conditions of 400 °C, 1 h, and an impregnation ratio of 3.
Abstract: Hydrochar was used to produce activated carbon with high BET surface area and large pore volume via phosphoric acid activation. The hydrochar described here can be obtained from hydrothermal carbonization of corn cob residue (CCR). Porous structure of activated carbons was characterized by nitrogen adsorption and scanning electron microscopy (SEM). Results showed that the specific surface area and total pore volume of activated carbon were increased to 2192 m2/g and 1.269 cm3/g, respectively, under conditions of 400 °C, 1 h, and an impregnation ratio of 3, from 5.69 m2/g and 0.136 cm3/g of the starting material. The chemical properties of hydrochar and activated carbons were further characterized by Fourier transform infrared spectroscopy (FT-IR), which confirmed the chemical transformation. Furthermore, the localized graphitic nature of the porous carbon was shown by the X-ray diffraction pattern. Thus, the adsorption capacity was enhanced for activated carbon in comparison with commercial carbon. The process of activated carbon preparation provided a high value-added application of hydrochar.
TL;DR: In this article, a series of epoxy resin-based nanocomposites were prepared in the form of coatings with various amounts of nanocellulose loadings, and the coatings were applied onto mild steel at room temperature.
Abstract: Nanocellulose (NC) is an attractive reinforcement agent that can be incorporated into protective coatings because it is a renewable, biodegradable, and biocompatible polymer resource. In this study, a series of epoxy resin-based nanocomposites were prepared in the form of coatings with various amounts of NC loadings, and the coatings were applied onto mild steel at room temperature. The characterizations of the NC and nanocomposites were performed via X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FTIR). The thermophysical properties of the nanocomposites were evaluated using differential scanning calorimetry (DSC) and thermogravimetry (TGA) analyses. The transparency of the nanocomposite specimens was examined by ultraviolet visible (UV-Vis) spectroscopy in the range of 300 to 800 nm. The corrosion protection properties of the coated mild steel substrates immersed in a 3.5% NaCl solution were studied comparatively by electrochemical impedance spectroscopy (EIS). The results showed that all of the nanocomposite coatings with NC noticeably influenced the epoxy-diamine liquid pre-polymer, both physically and chemically. Furthermore, the 1 wt.% NC nanocomposite coating system was found to have the most pronounced anti-corrosion properties, as confirmed by a 30-day EIS study.
TL;DR: In this paper, the chemical composition and selected physico-mechanical properties of pedunculate oak (Quercus robur L.) wood samples were assessed after thermal treatment.
Abstract: Changes in the chemical composition and selected physico-mechanical properties of pedunculate oak (Quercus robur L.) wood samples were assessed after thermal treatment. Heat treatment was performed at 160, 180, and 200 °C in an oxidizing atmosphere. The contents of the extractives, lignin, cellulose, holocellulose, and saccharides, and the structural changes in the functional groups were determined. Changes in the colour traits, wood density, compression strength parallel to the grain, and compression modulus of elasticity were also determined. The decrease in the holocellulose content caused by the degradation of non-glucosic saccharides was observed during thermal treatment. The contents of both the extractives and lignin increased. The syringyl to guaiacyl (S/G) ratio in the lignin increased because of the preferential condensation of guaiacyl units. The physical and mechanical properties of pedunculate oak wood, such as density, equilibrium moisture content, colour lightness, and yellowness, decreased as the temperature increased. The compression strength and redness varied during thermal treatment, and reached maximum values during the treatment at 180 °C. The modulus of elasticity showed non-significant differences. Three groups of heat treatment clusters were distinguished in the multivariate wood trait analysis and were clearly segregated from each other.
TL;DR: In this article, the feasibility of incorporating purified kraft lignin, at different concentrations ranging from 5 to 29%, into fiberboards made from corn residues was studied, and a Life Cycle Thinking (LCT) approach suggested that Lignin-based fiberboards are environmentally preferable than those based on thermosetting resins.
Abstract: The feasibility of incorporating purified kraft lignin, at different concentrations ranging from 5 to 29%, into fiberboards made from corn residues was studied. The lignin was obtained from black liquor, which is a residue of the paper industry. Corn stalk raw material and its thermomechanically produced fiber were characterized in terms of their chemical composition. The physical and mechanical properties of the resulting fiberboards were evaluated. The fiberboards produced following a wet process had good mechanical and water resistance properties that satisfied the requirements of the relevant standards. In addition, a Life Cycle Thinking (LCT) approach suggested that lignin-based fiberboards are environmentally preferable than those based on thermosetting resins.
TL;DR: In this article, a facile method was reported to prepare nanocellulose fibers from oil palm trunk fibers, which were pretreated 2 hours with NaOH/urea solution, and the fully swelled fibers were mechanically treated through high-pressure homogenization to obtain nanocells.
Abstract: A facile method is reported to prepare nanocellulose fibers from oil palm trunk fibers. The fibers were pretreated 2 hours with NaOH/urea solution, and the fully swelled fibers were mechanically treated through high-pressure homogenization to obtain nanocellulose. The nanocellulose fibers were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR results revealed that there was no obvious difference between the spectra of the bleached fibers (BF), pretreated cellulose fibers (PCF), and cellulose nanofibers (NCF), which indicated that the pretreatment process is a non-derivative reaction. The crystallinity of PCF and NCF decreased and contained the cellulose I crystal structure. The PCF presented both a distorted structure and a coarser surface. The resulting NCF were approximately 10 nm to 100 nm in diameter with the length varying from hundreds of nanometers to several micrometers, as observed by SEM. The thermal degradation of NCF was 223 °C with about 20% weight loss, and the maximum degradation temperature was 338 °C. NaOH/urea showed potential as a mild solvent for preparing nanocellulose fibers.
TL;DR: In this paper, the authors investigated the possibility of the estimation of important quantities in dimensional stability of Brazilian tropical woods by using the density at 12% moisture content, anhydrous density, and basic density.
Abstract: Wood is a material widely used in various sectors of construction, such as in structures and building components. The volume of wood extracted from tropical forests has reached a considerable amount, and this wood is marketed with popular names without prior characterization. Wood density is an easy property to measure, and its use as an estimator of other properties is very common in this sector. This study investigated the possibility of the estimation of important quantities in dimensional stability of Brazilian tropical woods by using the density at 12% moisture content, anhydrous density, and basic density. Testing the ability to estimate radial, axial, tangential, and volumetric shrinkage, anisotropy coefficient, coefficient of volumetric rate of volumetric shrinkage, as well as the rate of volumetric swelling using the densities above, with linear, exponential, geometric, and logarithmic models, the best determination coefficient was: R2 = 19.58%. The results were, in summary, that the variable density was not a good estimator of the dimensional stability of the wood.
TL;DR: In this article, the authors presented the possibility of creating motivational programs for employees working in small and medium-sized enterprises (SMEs) working in wood-processing industry in Slovakia.
Abstract: This paper presents the possibility of creating motivational programs for employees working in small and medium-sized enterprises (SMEs). The applicability of the proposed option is verified and presented to a medium-sized enterprise operating in the wood-processing industry in Slovakia. Using cluster analysis, three motivational-oriented groups were defined in the category of managers and three similar motivational-oriented groups in the category of workers. Subsequently, the sampling units were tested by the Tukey's honest significant difference (HSD) test. In this way, the significance of the differences in arithmetic mean and the standard deviation of the individual motivational factors of the monitored sets at the significance level α = 0.05 were defined. The result of the analysis is a plan to create a group motivational program. The content of this program is a common motivational factor for groups, supplemented by employee-specific factors. Currently, businesses apply unified motivational programs based on two, three, or four main motivators. However, improperly designed and applied motivational programs have a negative impact on employees and do not motivate them to maximize performance. By implementing this method in wood-processing SMEs, the company's performance can be increased, as the needs of most employees would be met.
TL;DR: In this paper, the effect of chemical composition on the defibrillation efficiency and properties of cellulose nanofibrils (CNFs) prepared by wet disk-milling was investigated using six different wood species.
Abstract: Cellulose nanofibrils (CNF) can be divided into lignocellulose nanofibrils (LCNF), holocellulose nanofibrils (HCNF), and pure cellulose nanofibrils (PCNF), dependent upon their chemical composition The effect of the chemical composition on the defibrillation efficiency and the properties of the CNFs prepared by wet disk-milling was investigated using six different wood species The defibrillation efficiency was improved when the lignin and hemicellulose was removed, and smaller fibers with diameters in the order of PCNF > HCNF > LCNF were produced The average diameter of the hardwood LCNF was finer than that of the softwood LCNFs, but there was no noticeable difference in the diameters of the HCNF and the PCNF from the different wood species The filtration time of CNF suspensions and the tensile properties of nanopaper sheets were longer and higher, respectively, in the order of HCNF > PCNF > LCNF from different wood species
TL;DR: In this article, the authors considered whether the proximity of alkaline particles within such documents is sufficient to neutralize the acidic species present, and they concluded that incomplete neutralization is possible with nonaqueous dispersion.
Abstract: Deacidification refers to chemical treatments meant to slow down the acid hydrolysis and embrittlement of books and paper documents that had been printed on acidic paper. From the early 1800s up to about 1990, papermakers used aluminum sulfate, an acidic compound, in most printing papers. Certain deacidification methods use non-aqueous media to distribute alkaline mineral particles such as MgO within the pages of the treated books. Evidence is considered here as to whether or not the proximity of alkaline particles within such documents is sufficient to neutralize the acidic species present. Because much evidence suggests incomplete neutralization, a second focus concerns what to do next in cases where books already have been treated with a non-aqueous dispersion system. Based on the literature, the neutralization of acidic species within such paper can be completed by partial moistening, by high humidity and pressure, by water condensation, as well as by optional treatments to enhance paper strength and a final drying step.
Journal Article•
TL;DR: The nutritional components (rice straw, magnesium sulphate, and calcium chloride concentrations) and physical parameters (temperature and pH) for xylanase production with a newly isolated Aspergillus oryzae LC1 under submerged fermentation using central composite design based response surface methodology were optimized.
Abstract: Xylanase is a key enzyme in the conversion of lignocellulosic biomass into various oligosaccharides and simpler monomeric units through the hydrolysis of hemicellulose. Rice straw is readily available around the world and is a rich source of hemicellulose. Recently, there has been growing interest in the exploitation of rice straw as a low-cost substrate for the production of hemicellulolytic enzyme, i.e., xylanase. This study aimed to optimize the nutritional components (rice straw, magnesium sulphate, and calcium chloride concentrations) and physical parameters (temperature and pH) for xylanase production with a newly isolated Aspergillus oryzae LC1 under submerged fermentation using central composite design based response surface methodology. The optimum media constituents were 1% rice straw (w/v), 1.0 g/L calcium chloride, and 0.3 g/L magnesium sulphate, and the optimum physical parameters were pH 5 and 25 °C. The statistical design showed increased xylanase production with a maximum activity of 935 ± 2.3 IU/mL. The enzyme production was 3.8-fold higher than for the un-optimized Mendel’s Stenberg Basal Salt medium (245 ± 1.9 IU/mL). The enzyme was stable over wide ranges of pH (3 to 10) and temperature (25 to 60 °C). The partially purified xylanase enzyme was used for the enzymatic hydrolysis of different lignocellulosic agro-residues.
TL;DR: In this article, Olive tree pruning was water extracted and pretreated by dilute sulfuric acid to achieve high sugar recoveries from cellulosic and hemicellulosic fractions.
Abstract: Olive tree biomass (OTB) represents an interesting feedstock for bioethanol production. In this study, olive tree pruning was water extracted and pretreated by dilute sulfuric acid to achieve high sugar recoveries from cellulosic and hemicellulosic fractions. Temperature (160 to 200 °C), acid concentration (0 to 8 g acid/100 g extracted raw material), and solids loading (15% to 35% w/v) were selected as operation variables and modified according to a Box-Behnken experimental design. The optimal conditions for the acid pretreatment were 160 °C, 4.9 g sulfuric acid/100 g biomass, and 35% solids loading (w/v), according to multiple criteria that considered the maximization of both the hemicellulosic sugars concentration in prehydrolysate and the overall sugar yield. These optimized conditions yielded a sugar concentration of 79.8 g/L, corresponding to an overall yield of 39.8 g total sugars/100 g extracted OTB. The fermentability of hemicellulosic sugars prehydrolysates from the acid pretreatment was evaluated by Escherichia coli after a detoxification stage by overliming. The prehydrolysates with lower concentrations of toxic compounds were fermented and achieved ethanol yields higher than 80% of the theoretical ethanol yield.
TL;DR: In this paper, a method for simultaneous pectin extraction and pretreatment (SPEP) of citrus waste (CW) by dilute nitric acid and ethanol, almost all of the CW was converted to bio-derived chemicals in a single-step process at a low/moderate temperature, performed at different temperatures (70 °C and 80 °C), pH (1.8, 3.0, and 4.3), and extraction times (2 h and 3 h).
Abstract: In a novel valorization approach for simultaneous pectin extraction and pretreatment (SPEP) of citrus waste (CW) by dilute nitric acid and ethanol, almost all of the CW was converted to bio-derived chemicals in a single-step process at a low/moderate temperature. The SPEP was performed at different temperatures (70 °C and 80 °C), pH (1.8, 3.0, and 4.3), and extraction times (2 h and 3 h) with a full factorial design. The maximum pectin yield of 45.5% was obtained at pH 1.8, 80 °C, and 2 h. The pectin yields at pH 1.8 were much higher than at pH 4.3 and 3. Also, the degree of methyl-esterification at pH 1.8 was higher than 50%, whereas at the higher pH, low methoxyl pectins were extracted. The treated CW obtained after the SPEP, free from limonene, was subjected to separate cellulolytic enzymatic hydrolysis and ethanolic fermentation. The glucose yields in the enzymatic hydrolysates were higher for the CW treated at pH 1.8. The fermentation of the enzymatic hydrolysates by Mucor indicus resulted in fungal biomass yields in the range of 355 to 687 mg per g of consumed sugars. The optimum conditions for obtaining the maximum SPEP yield (glucose + pectin (g) / raw material (g))*100) were pH 1.8, 80 °C, and 2 h, which resulted in a yield of 58.7% (g/g CW).
TL;DR: In this paper, the effects of ashing temperature on ash fouling and slagging characteristics were investigated in three typical biomass fuels (rice husk, rice straw, and corn cobs).
Abstract: Three typical biomass fuels—rice husk, rice straw, and corn cobs—were combusted to understand the effects of ashing temperature on ash fouling and slagging characteristics. The ashes generated from combustion at 600 °C and 815 °C were characterized thoroughly with regard to their chemical composition. The systematic slagging/fouling indices of biomass were used to study the effects of ashing temperature on ash fouling and slagging propensities. The results showed that ashing temperature had a remarkable influence on ash composition, particle size distribution, ash morphology, ash fusibility, and thermal properties. Increased ashing temperature resulted in the expansion of ash particles together with the volatilization of alkali metals in the form of inorganic salts. Morphology analysis indicated that high ashing temperatures promoted biomass ash slagging. Ash fusion points increased at elevated ashing temperatures, while the ash content decreased. As a result of the volatilization and decomposition of biomass ash, a four-step mechanism of weight loss was clearly identified by thermal analysis. All prepared biomass ashes resulted in slagging and fouling problems at different levels during the thermo-chemical conversion of biomass.
TL;DR: In this article, the thermal degradation and thermal stability of composite materials were studied in a nitrogen atmosphere. And the authors showed that the hybrid and non-hybrid composites exhibited similar thermal-induced degradation profiles that had only one mass loss step.
Abstract: Thermogravimetric analysis and differential scanning calorimetry were used to study the thermal degradation and thermal stability of bamboo powder and its composites (EP-BFC) in a nitrogen atmosphere. The thermal stability of EP-BFC decreased as the bamboo filler-loading increased. Compared with epoxy, bamboo powder had a lower thermal stability, which reduced the thermal stability for the higher filler-loading composites. The addition of glass fibre to the EP-BFC improved the thermal stability of the new hybrid composites. Both the hybrid and non-hybrid composites exhibited similar thermal-induced degradation profiles that had only one mass loss step. However, a noticeable difference between the percentage value of the degradation between both the hybrid and non-hybrid composites showed that the EP/G-BFC hybrids were more thermally stable than the non-hybrid EP-BFC. Different materials experienced different activities, which were clearly shown from the DSC analysis. Bamboo fibre and non-fully cured epoxy exhibit exothermic peaks, while fully cured epoxy exhibits an endothermic peak.
TL;DR: In this article, the authors developed activated carbons (ACs) from the agricultural by-products of moso bamboo by pyrolysis carbonization and the KOH activation process, and the results showed that the developed bamboo ACs achieved surface areas (SBET) as high as 3208 m2/g and micropores volumes (VDR).
Abstract: Activated carbons (ACs) were developed from the agricultural by-products of moso bamboo by pyrolysis carbonization and the KOH activation process. N2 adsorption-desorption at 77 K, thermogravimetric analysis (TG), X-ray photoelectron spectrometry (XPS), element analysis (EA), X-ray diffraction (XRD), scanning electron microscopy (SEM), high- resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR) were used to investigate the synthesis process, the impact of the weight ratio of KOH/bamboo charcoal (BC), and the characteristics of the bamboo charcoal and ACs produced. The results showed that the developed bamboo ACs achieved surface areas (SBET) as high as 3208 m2/g and micropores volumes (VDR) as high as 1.01 cm3/g. The carbonation and activation of the bamboo resulted in the enhancement of the microstructure of the bamboo ACs, and hence improvements in the sorption behavior and storage capacity. The highest hydrogen storage capacities achieved were 6.6 wt.% at 4 MPa and 2.74 wt.% at 1 bar, both at 77 K, which were much higher than those of a well-known commercial activated carbon.