Eucalyptus Pulp Research Articles

Evaluation of Xylooligosaccharides Production for a Specific Degree of Polymerization by Liquid Hot Water Treatment of Tropical Hardwood.

Eucalyptus pellita is known as attractive biomass, and it has been utilized for eucalyptus oil, furniture, and pulp and paper production that causes a significant amount of byproducts. Liquid hot water treatment depending on combined severity factor (CSF) was subjected to isolate hemicellulose fraction from E. pellita and to produce xylooligosaccharides (XOS). The xylan extraction ratio based on the initial xylan content of the feedstock was maximized up to 77.6% at 170 °C for 50 min condition (CSF: 1.0), which had accounted for XOS purity of 76.5% based on the total sugar content of the liquid hydrolysate. In this condition, the sum of xylobiose, xylotriose, and xylotetraose which has a low degree of polymerization (DP) of 2 to 4 was determined as 80.6% of the total XOS. The highest XOS production score established using parameters including the xylan extraction ratio, XOS purity, and low DP XOS ratio was 5.7 at CSF 1.0 condition. XOS production score evaluated using the CSF is expected to be used as a productivity indicator of XOS in the industry (R-squared value: 0.92).

Fabrication of super-high transparent cellulose films with multifunctional performances via postmodification strategy

A transparent versatile cellulose platform film was prepared from Eucalyptus pulp in this work. Based on such cellulose platform, multifunctional cellulose films with ultraviolet-shielding, photochromism, and strong mechanical strength were fabricated via nucleophilic postmodification strategy by introducing a versatile spiropyran moiety into cellulose molecules. The fabricated cellulose films exhibited super-high transmittance up to 96% and performed notable ultraviolet-shielding capacity at 200–400 nm. Moreover, the photochromic performance of cellulose films with color changes could be clearly observed by the naked eyes, and the fluorescent blue could be excited. Besides, the tensile stress of multi-functional cellulose film was about 80 MPa, which was almost 8 times stronger than that of the commercial polyethylene film at the same thickness. It is noteworthy that these superior performances promote such a cellulose platform to be a versatile precursor for fabricating various multi-functional cellulose used in the fields of out-door coating, transparent packaging, optical screen,etc.

Increasing the Possibilities of TEMPO‐Mediated Oxidation in the Production of Cellulose Nanofibers by Reducing the Reaction Time and Reusing the Reaction Medium

Abstract2,2,6,6‐Tetramethylpiperidine‐1‐oxyl (TEMPO)‐mediated oxidation of cellulose is the most effective pretreatment to obtain highly fibrillated cellulose nanofibers (CNFs). However, the associated environmental impact and the high operational costs have limited its implementation at large scale. This study aims to improve the effectiveness of this pretreatment by reducing the oxidation time and reusing the reaction medium, with the ultimate objective of upscaling a more viable sustainable process. The results show the possibility of reducing the reaction time by 85% and 60% in the case of cotton and eucalyptus pulps, respectively, without altering the properties of the obtained CNFs (carboxyl groups, nanofibrillation yield, cationic demand, and morphology). The reuse of 75% of the reaction medium for ten cycles, do not alter the properties of the CNFs either. With this approach, the consumption of TEMPO and NaBr is reduced by 67%, while that of NaClO is decreased by 42% and 22% in the oxidation of cotton and eucalyptus cellulose, respectively. At the same time, the environmental concerns derived from the disposal of the catalysts are considerably reduced.

Using hydrocyclone fractionation to improve chemical pulp quality

Production of chemical pulp is accompanied by various impurities in addition to the cellulose fibres produced. The impurities are mainly due to lignin fragments and wood resin components in the wood. The possibility of removing impurities such as fines and extractives at the early production stages by hydrocyclone fractionation was investigated.A sample of unbleached eucalyptus chemical pulp was fractionated using a hydrocyclone at feed consistencies of 0.1% to 1.0% and mass reject rates of 5% to 41%. Fractionation efficiency was assessed by measuring changes in consistency, Canadian Standard Freeness, fibre morphology, and extractives (wood resin) in the fibres.It was found that fractionating at consistencies of 0.6 - 1.0% at mass reject rates of 5 – 20% produced acceptable fractionation, with simultaneous removal of extractives associated with fibre fines.Fractionation of unbleached chemical pulps under these conditions could produce chemical pulps with enhanced bleaching and further processing properties.

Kraft Cooking with Teak Wood Extract and Determining Residual 2-Methylanthraquinone in Eucalyptus Pulp

Kraft Cooking with Teak Wood Extract and Determining Residual 2-Methylanthraquinone in Eucalyptus Pulp

Evaluation of Anionic Eco-Friendly Flocculants Prepared from Eucalyptus Pulps with Diverse Lignin Contents for Application in Effluent Treatment.

Modification of cellulosic-rich materials for the production of cellulose-based polyelectrolytes (PELs) can bring several benefits, such as high biodegradability and low or no toxicity, for numerous applications, when compared with the use of traditional, synthetic PELs. Moreover, cellulose-based PELs originating from wood wastes, contribute to the valorisation of such wastes. In this work, Eucalyptus pulps with diverse lignin contents, extracted from Eucalyptus wood wastes, were anionized by a two–step reaction procedure (periodate oxidation followed by sulfonation). Applying different reaction times (24–144 h) in the sulfonation step allowed for producing a range of cellulose-based anionic PELs with different characteristics. PELs obtained after 24 and 72 h of sulfonation were thoroughly characterized (Fourier transform infrared and 1H nuclear magnetic resonance spectroscopies, anionic group content (elemental analysis), zeta potential and hydrodynamic diameter (dynamic light scattering)) and subsequently evaluated as flocculants in decolouration processes of model effluents (Methylene Blue and Crystal Violet) and an industrial effluent from a textile industry. Furthermore, possible flocculation mechanisms induced by the use of the various PELs are discussed. Results are compared with those obtained with a commonly applied, synthetic flocculant (polyacrylamide). It is demonstrated that it was possible to obtain water-soluble lignocellulosic PELs starting from raw materials with different degrees of purity and that those PELs are promising eco-friendly alternative flocculation agents for the decolouration of effluents.

Enhanced Mechanical Properties of Eucalyptus-Basalt-Based Hybrid-Reinforced Cement Composites.

The present study describes the manufacturing of flat sheets of eucalyptus-basalt based hybrid reinforced cement composites (EB-HRCC). The potential of basalt fibrous waste (BFW) as a reinforcement agent in cement matrices and its effects on mechanical and interfacial properties were evaluated in detail. Significantly enhanced bending (flexural) strength and ductility were observed for all developed composite samples. BFW and eucalyptus pulp (EP) were utilized as reinforcement and filling agents respectively for EB-HRCC samples. Mechanical, microstructural and physical properties of EB-HRCC samples were investigated with different formulations of BFW with EP in cement matrices. The results showed that physical properties of the composite samples were more influenced by fiber content. For standard mechanical analysis, the composite samples were placed in sealed bags for two days, thermally cured at 60 °C for five days and immersed in water in ambient conditions for one day. The obtained results showed that samples prepared under optimized conditions (4% EP and 2% BFW) had significantly higher flexural strength and bulk density with lower water absorption and apparent void volume (porosity). Moreover, the higher percentage of BFW significantly enhanced the values of modulus of rupture (MOR), modulus of elasticity (MOE), specific energy (SE) and limit of proportionality (LOP). The effects of entrapped air under the four-point bending test on the mechanical behavior of hybrid composites were also investigated in this thematic study. The composites were designed to be used as roofing tile alternatives.

Polyploidy as a strategy to improve the industrial quality of eucalypt wood

There are many studies describing the physical and anatomical properties of eucalypt wood, but studies comparing the performance of diploid and polyploid clones in terms of wood anatomy and wood quality are scarce. In this context, this study aimed to compare the performances of Eucalyptus diploid and polyploid clones with the same genetic origin by analyzing the physical and anatomical properties of the wood to extend the information on wood quality for pulp and paper production. Woods samples from eucalypt hybrids (E. grandis x E. urophylla) from experimental plantations of Suzano S.A. were used. Moisture content, basic density and fiber size were determined. The data related to these variables were tested by analysis of variance. Moisture content in polyploids was 4% higher than in diploids. The mean basic density in diploid clones was 13% higher than in polyploid clones, although there was no significant difference between one of the evaluated clones. The mean fiber length in polyploid clones was 18% higher than in diploid clones. No significant differences were found in the wood quality indexes for cellulosic pulp production. Synthetic polyploid clones of eucalypt presented lower basic density and fibers with higher length and wall thickness when compared to diploids, indicating the potential use of polyploids in eucalypt pulp and paper production.

3D fiber models to simulate and optimize tissue materials

Tissue materials development using 3D computational tools to predict the influence of the combination of different fibers can be employed in the design of innovative tissue products and furnish optimization. Fibrous materials can be designed using different 3D fiber models for each type of fibers, detailed to the point where the wall fiber thickness, fiber lumen, and collapse degree are considered and presented in this work. Eucalyptus, Pinus, and Picea kraft cellulose pulp fibers were selected because they are representative of differentiated fiber types. The fiber morphological measurements were obtained using two methods: one uses the fibers in suspension, without restraints, and the other uses a capillary fiber alignment. The results indicate good repeatability for both methods but differences of 14% for fiber length weighted in length, 2% for fiber width, 11% for coarseness, 35% for curl, and 88% for fines content. Scanning electron microscopy images were used to identify the fiber dimensions inside the tissue structure. Four different types of fiber models for eucalyptus fibers, with different fiber wall thickness and lumen dimensions, were presented and used to predict 3D computational fibrous structures.

Large eddy simulation of turbulent pulp flow in a channel

Large eddy simulation (LES) of turbulent flow of concentrated fiber suspension or pulp is carried out to investigate the flow and turbulence structures in a channel. The simulations are carried out for the turbulent flow of Eucalyptus pulp suspension using OpenFOAM for three fiber concentrations (c = 1.5, 2.0 and 2.5) and six different Reynolds numbers (6 ≤Res≤ 16,600). It is observed that the variation in flow regime is similar in the two lower fiber concentrations while the flow regime is highly affected by fiber concentration for c = 2.5. Visualizations of vortical structures for different Reynolds numbers and fiber concentrations are used to investigate different flow regimes. Variation of apparent viscosity with Reynolds number and fiber concentration is also presented to show its effect on the turbulent properties of fiber suspension flow. It is shown that the deviation of turbulent velocity profile from that of a Newtonian flow increases with an increase in Reynolds number and fiber concentration. Also, the extend of buffer layer increases at higher Re. Using the calculated turbulent velocity profile, the values of constant in logarithmic velocity profile is proposed for fiber suspension. Finally, a discussion is presented on the variation of turbulent intensities and Reynolds stress with Reynolds number and fiber concentration.

Cleaner approach for medium consistency eucalyptus slab pulp production using ozone bleaching under turbulent mixing

Eucalyptus slab (ES), a cellulosic waste from wood processing is abundant and can be utilized for the pulping in many wood scarce countries. However, during chlorine dioxide (ClO2) bleaching, which is the current applied bleaching technique for medium consistency eucalyptus slab pulp (MC-ESP), toxic absorbable organic halides (AOX) is still generated, causing pollution to the water environment. Applying ozone gas (O3) to replace ClO2 for MC-ESP bleaching is a promising alternative way since O3 is a clean and powerful oxidizing agent but not producing AOX pollutant. In this work, the influences of the three most important O3-bleaching factors, i.e., O3-concentration, O3-dosage and mixing intensity to the bleaching properties of MC-ESP was systematically evaluated. It was found that increasing of O3-concentration and O3-dosage greatly improved the properties of MC-ESP. Turbulent mixing intensity had a effective effect on improving O3-bleaching of MC-ESP. The high O3-concentration (170 mg/L), 1.0% O3-dosage and 1200 rpm rotational speed were found to be optimum conditions for O3-bleaching of MC-ESP. Under this condition, the brightness, kappa number and viscosity of the pulp obtained were similar or even better than those of the ESP after bleaching with similar or higher ClO2-dosage, however, without generating toxic AOX and with lower pollution load of effluent. This research provided important supports for the development of MC-ESP cleaner production by reducing the pollutant from ClO2 bleaching. Such approach of using wood processing waste as raw material, O3 gas as AOX-free bleaching agent could provide the excellent options for eco-friendly pulp production.

Preparation of high oil absorption microfiber cryogels by mechanical method

Poplar alkaline peroxide mechanical pulp (APMP) was used as plant fiber raw material, and it was graded according to the lignin content. The graded raw materials were used to prepare lignin-containing microfibers (LCMFs) by micro-grinding, and then, the lignin-containing microfiber cryogels (LCMF-cryogels) were prepared by vacuum freeze-drying. The particle size distribution, micromorphology and dispersion stability of LCMFs were characterized by laser diffraction particle size analyzer, transmission electron microscopy and Zeta potentiometer. Then, the crystalline structure, pore structure, surface morphology and adsorption properties of LCMF-cryogels were analyzed. In addition, LCMF-cryogels were compared with the microfiber cryogels (MF-cryogels) which use commercial eucalyptus chemical bleaching pulp as raw material. It was proved that using poplar APMP as raw material to prepare cryogels is more advantageous. The results showed that the lower the lignin content in plant materials, the better the oil adsorption ability of cryogels. This is because the binding effect of lignin on the fiber is reduced, which makes the fibrillation of the fiber easier by external mechanical action. The maximum adsorption capacity of LCMF-cryogel for methyl silicone oil is 215 g/g, while that of MF-cryogel prepared from commercial eucalyptus chemical bleaching pulp is 102.5 g/g. The analysis of the properties of raw fiber and the gel pores shows that the change in the fiber morphology caused by different pulping methods has important influence on the development of LCMF-cryogels by mechanical refining. Poplar APMP is more suitable for preparing fiber-based cryogels oil-absorbing materials than commercial eucalyptus chemical bleaching pulp.

Natural Rubber Latex Foam Reinforced with Micro- and Nanofibrillated Cellulose via Dunlop Method.

Natural rubber latex foam (NRLF) was reinforced with micro- and nanofibrillated cellulose at a loading content of 5–20 parts per hundred of rubber (phr) via the Dunlop process. Cellulose powder from eucalyptus pulp and bacterial cellulose (BC) was used as a microcellulose (MC) and nanocellulose (NC) reinforcing agent, respectively. NRLF, NRLF-MC, and NRLF-NC exhibited interconnected macroporous structures with a high porosity and a low-density. The composite foams contained pores with sizes in a range of 10–500 µm. As compared to MC, NC had a better dispersion inside the NRLF matrix and showed a higher adhesion to the NRLF matrix, resulting in a greater reinforcement. The most increased tensile strengths for MC and NC incorporated NRLF were found to be 0.43 MPa (1.4-fold increase) and 0.73 MPa (2.4-fold increase), respectively, by reinforcing NRLF with 5 phr MC and 15 phr NC, whereas the elongation at break was slightly reduced. Compression testing showed that the recovery percentage was improved to 34.9% (1.3-fold increase) by reinforcement with 15 phr NC, whereas no significant improvement in the recovery percentage was observed with MC. Both NRLF-MC and NRLF-NC presented hydrophobic surfaces and good thermal stability up to 300 °C. Due to their highly porous structure, after a prolong immersion in water, NRLF composites had high water uptake abilities. According to their properties, the composite foams could be further modified for use as green absorption or supporting materials.

Refining characteristics of isometric straight bar plates with different bar angles

Bar angle is one of the most important parameters of an isometric straight bar refiner plate and its effects on the change in pulp and paper properties during refining is still unclear. This study investigated the effect of plate bar angle on refining quality and refining efficiency by clarifying the definition of bar angle. Five isometric straight bar plates with different bar angles were used in low consistency refining of bleached sulphate eucalyptus pulp (BSEP). Samples at different refining time intervals were collected, and the fibers, pulp, and paper properties were detected and analyzed. There was a great influence of bar angle on the fibers, pulp, and paper properties. Additionally, a critical static attack angle, or critical bar angle for plates with specific field angle, existed. The modification of fibers and pulp properties was strong when the plate reached a critical bar angle. Meanwhile, there was an optimal static attack angle for a plate with specific field angle, when considering paper properties such as tensile index and tear index. The refining time was shortest when the pulp was refined by the plate with critical bar angle, allowing the paper properties to reach a maximum value. It was shown that the static attack angle of refining should be selected in the range of 45º to 70º, which includes the optimal value and the bar angle was proposed in the range of 11.25º to 23.75º for the plate with common field angle of 22.5º.

Study of LCNF and CNF from pine and eucalyptus pulps

AbstractNanocelluloses produced from wood pulp are widely studied for various economic applications. Most studies of cellulose nanofibrils (CNF) use lignin-free fibres obtained from bleached pulps; however, unbleached fibres with residual lignin may also be used to obtain lignocelluloses nanofibrils (LCNF). Research on lignocellulose nanofibrils is a recent subject in the field; thus, the aim of the present study was to determine the ultrastructure of lignocellulose nanofibrils compared to cellulose nanofibrils produced from the same raw material. Understanding of nanoparticle properties is of great relevance for their various applications; therefore, complete characterisation of the chemical, physical, and morphological structures of LCNF and CNF produced from pine and eucalyptus woods was performed. Unbleached cellulosic fibres are a viable alternative for LCNF production, which has properties comparable to that of traditional CNF production that uses lignin-free fibres. LCNF from pine and eucalyptus were obtained with 4.0 % and 1.8 % residual lignin, respectively. The nanofibrils had high thermal stability because LCNF had a higher maximum degradation temperature. Due to the low interaction of lignin with water, LCNF had a lower water retention value than CNF.

Optimizing the modified atmosphere parameters in the carbonation process for improved fiber-cement performance

The objective of this work was to evaluate the effect of the relative humidity on the accelerated carbonation process of the fiber-cement composites reinforced with a high concentration of vegetable fibers. The samples were produced with 10% of bleached eucalyptus pulp, in a method of fabrication similar to the commercial boards. The composites were submitted in an atmosphere with CO2 saturation, and relative humidity range of 60–90% to evaluate the effect of this parameter on the development of carbonation reaction. X-ray diffraction and thermogravimetric analysis were accomplished at different times, for monitoring the formation of carbonates along the accelerated carbonation process. Microstructure, physical and mechanical properties, and degradation were also evaluated. The composites carbonated with 60% of relative humidity presented a formation of CaCO3 significantly higher (37%) than the other concentrations of relative humidity (70, 80 and 90%) in just 4 h of carbonation. The densification of the cementitious matrix increased by 17%, and the modulus of rupture by 43% compared to non-carbonated composites. There was no statistically significant difference between the relative humidity of 60 and 70% for the physical and mechanical properties of the materials, and in general, the carbonation process preserved the reinforcement capacity of eucalyptus pulp in fiber-cement even after the accelerated aging cycles. In conclusion, this study demonstrated that the concentration of the relative humidity of the curing atmosphere is the main vehicle for diffusion and reactivity of the accelerated carbonation process. The use of the ideal relative humidity content can provide a faster and more effective carbonation reaction, in the production of fiber-cement materials.

Chemical characterization and ultrastructure study of pulp fibers

Understanding the ultrastructure and chemical characterization of pulp fibers is highly important in utilizing wood as a raw material in a wide scope of applications, such as forest biomass-based biorefineries and low-cost renewable materials. The observation of the ultrastructure is not possible without advanced microscopy and spectroscopy techniques. Therefore, this study focuses on exploring the ultrastructure of pulp fibers with helium ion microscopy (HIM) and scanning electron microscopy (SEM). For the analysis of chemical characterization in the pulp fibers, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) were performed. For these studies, the pulp fiber samples were obtained mainly from three different wood species, i.e. spruce, birch and eucalyptus. They were received in the never dried state and dried with a critical point drier (CPD) to minimize pore collapse. The spectroscopy results showed a strong signal from crystalline cellulose and confirmed the absence of lignin after Kraft pulping and bleaching. However, with XPS about 2% of lignin was detected in eucalyptus pulp. The results obtained with the microscopy techniques are compared and indicating the nanofibril size, shape, surface roughness as well as their orientation in pulp fibers. To our knowledge, this is the first time that HIM is applied to study the ultrastructure of pulp fibers and compared against more conventional microscopy and spectroscopy techniques. The main differences between HIM and SEM were found to be related to the focusing and magnification. The individual nano- and microfibrils as well as their bundles were more easily visible with HIM than with SEM. Also, with HIM it was possible to get the total area in focus at once which was not the case with SEM. The increased understanding of the ultrastructure and chemical composition of wood pulp enhance the development of novel wood-based products and processes for their manufacture.

Relationship between Surface Properties and Fiber Network Parameters of Eucalyptus Kraft Pulps and Their Absorption Capacity

Water absorption capacity is a key characteristic of cellulosic pulps used for different commodities. This property is influenced by the affinity of the pulp fiber surface with water, chemical composition of the pulp, morphology, and organization of fibers in the network. In this study, surface properties of six industrial Eucalyptus bleached kraft pulps (fluff pulps) dry-defiberized in a Hammermill, which were obtained by wood pulping and pulp bleaching under different production conditions, were studied while employing dynamic water vapor sorption and contact angles measurements. The absorption properties of air-laid pulp pads were analyzed following the absorbency testing procedure and the relationship between these properties and pulp’s chemical composition and fiber network structure were assessed by multivariate analysis. The results showed that the accessibility of the fiber surface is related to the reduction of the contact angles, but, at the same time, to the longer absorption time and less absorption capacity of the fiber network. Therefore, the absorption properties of the pulps are not necessarily directly related to their surface properties. Indeed, absorptivity is related to the surface chemical composition, fiber morphology, and fiber network structure. Thus, surface carboxylic groups promote total water uptake, resulting in better absorption capacity. Greater fiber coarseness and deformations (curl and kink) provide a less wettable surface, but a more porous network with higher specific volume, resulting in more absorbent air-laid formulations.

Characterization of reversible and irreversible foulants in membrane bioreactor (MBR) for eucalyptus pulp and paper mill wastewater treatment using fluorescence regional integration

Abstract Membrane bioreactors (MBRs) are an alternative technology to achieve high quality effluent for water reuse for eucalyptus pulp and paper (P&P) industries, but membrane fouling is still a challenging factor that restricts its application. This study aims to investigate characteristics of reversible and irreversible fouling of the submerged polyvinylidene fluoride (PVDF) MBR for treating eucalyptus P&P wastewater. Six batches of MBR experiments with different mixed liquor suspended solids (MLSS) concentrations were performed. The membrane cleaning protocol included three-steps: backwashing with DI water and subsequently NaOH solution, and then soaking with NaOCl solution, for which achieved 54.6 ± 11 %, 76.6 ± 10 % and 97.8 ± 2 % of flux recovery, respectively. Formation of a cake layer comprised of organic substance and soluble microbial products (SMPs), mostly polysaccharides and proteins, was the main contributor to flux decline of the MBR. Concentration of proteins in the irreversible foulant was found to be positively correlated with degree of membrane fouling. Using fluorescence excitation-emission matrix (EEM) with fluorescence regional integration (FRI) analysis revealed that, during MBR treatment, protein-like substances in the permeate water significantly decreased, simultaneously with the increase in relative proportions of humic-like and fulvic-like substances. Further analysis on the irreversible foulants showed that protein-like substances, including tyrosine-like and tryptophan-like substances, were disproportionately more important to membrane fouling than humic-like substances relative to their respective concentration in raw P&P wastewater.

Olive oil stability in Pickering emulsion preparation from eucalyptus pulp and its rheology behaviour

In the present work, olive oil stability in Pickering emulsion from eucalyptus pulp was determined. The effect of oil concentrations, modified ammonium persulphate cellulose nanocrystals (APS-CNC) concentrations and pH on the drop sizes and distribution of Pickering emulsion were established. The emulsion stability was investigated in terms of zeta potential, %emulsion physical stability (ES) and %remains antioxidant activity. The smallest drop size of 8.00 ± 3.94 µm was obtained at 0.1 wt% of APS-CNC concentration, 10 wt% of oil concentration and pH 7. Also, the maximum %remain antioxidant activity of 44.94 ± 3.66% was acquired at 0.1 wt% APS-CNC concentration at pH 7 after 30 storage days. The rheology behaviour of these Pickering emulsions caused by shear-thinning fluid. This fluid behaviour can be applied to liquid food, cream and oral drug delivery with a nanocarrier.