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This work has focused on oxygen’s role in the delignification process within the context of pulp production. We have investigated the role of oxygen in a complex set of chemical reactions taking place during this process, including both oxidative and non-oxidative reactions. This study explores the impact of pH changes during the oxygen delignification process and the characteristics of the resulting pulps. Additionally, this research examines the effect of oxygen, by comparing conventional oxygen delignification with trials using air and nitrogen. Industrial softwood kraft pulps with a kappa number of 35 were subjected to delignification for 20–120 min under alkaline conditions. The resulting pulps were assessed for kappa number, intrinsic viscosity, fiber charge, and ISO brightness. An important observation from this research is the reduction in lignin molecular weight upon exposure to oxygen and air, suggesting depolymerization reactions facilitated by oxygen species, whereas nitrogen exposure results in less pronounced changes. This finding underscores the impact of oxygen in altering lignin structure, thus informing the selectivity and effectiveness of the delignification process. [ABSTRACT FROM AUTHOR]

For sustainable use of lignocellulosic resources, pruned tree branches of cocoa, one of the major evergreen tropical tree crops with significant economic importance worldwide, were investigated as a potential source of kraft pulp. This study determined the chemical composition, fiber dimensions, kraft pulp, and paper properties of the cocoa tree (Theobroma cacao L.) branches compared to the deciduous trees traditionally used in the paper industry. A handsheet of cocoa pulp showed promising results with narrow fiber length distribution, high paper density, and high mechanical strength. The yield of kraft pulp made from cocoa branches wood was lower. The tensile and burst indices of cocoa pulp handsheet were 2 and 2.5 times higher than that of hardwood traditionally used in the paper industry. These results suggest a potential use of cocoa (Theobroma cacao L.) tree branch wood for pulp production using the kraft process. [ABSTRACT FROM AUTHOR]

This study investigates the role of secondary condensates in the pulp and paper industry's journey to minimize its water footprint. The integration of secondary condensates, traditionally less explored in bleaching processes, is examined for its potential in reducing freshwater demand. Condensates with different organic content (chemical oxygen demand, COD) and their mixtures were tested as washing liquid after the alkaline extraction stage (EP) of eucalyptus globulus kraft pulp and compared to hot water. Two subsequent chlorine dioxide stages were applied to evaluate the impact of the washing liquid COD on pulp properties and chemicals consumption. Despite its higher organic content, the condensates can be used as a partial or total substitute for hot water without substantial compromises in the pulp properties, such as brightness, reversion, and viscosity. The calculated correlation between ClO2 consumption and COD in the washing liquid can be applied for assessing economic and environmental trade-offs, providing a roadmap for optimizing processes and reducing environmental impacts. [ABSTRACT FROM AUTHOR]

The growing concern for a safer chemical industry has spurred research towards replacing strong acid solvents, because of the significant hazards they cause, such as issues related to effluent treatment and high corrosiveness. In the production of nanocellulose, sulfuric acid stands out as an example, being highly corrosive, yet widely used. This study aimed to investigate a more ecological acid mixture solvent, specifically comprising hydrochloric acid (HCl) and citric acid (CA), for obtaining carboxylated nanocellulose from kraft cellulose pulp. Distinct methodologies were employed based on three different durations, corresponding to each methodology (30 minutes, 60 minutes, and 90 minutes). FTIR analysis confirmed the occurrence of chemical modification. Among these methodologies, ultrasonication for 60 minutes yielded the best carboxylated nanocellulose, as determined through morphological analysis, with an average diameter of 8.4 nm and an average length of 123 nm. X-ray diffraction (XRD) revealed a decrease in crystallinity; however, both kraft pulp and carboxylated nanocellulose exhibited the cellulose Iβ allomorph. This surface modification paves the way for incorporating new functional properties into the design of composites, hydrogels, Pickering emulsions, drug delivery systems, food packaging, and biofilms. [ABSTRACT FROM AUTHOR]

Africa is the third-richest continent in the world in terms of bamboo species. Despite these laudable natural resources, most African countries still use asbestos cement board as one of their major building materials. This is chiefly due to the high cost of equipment and technologies associated with non-asbestos-fiber cement board production. The current research seeks to underscore the possibility of utilizing these massive continent resources for non-asbestos-fiber cement board production by employing the existing production process in the asbestos cement industries via an innovatively developed laboratory-simulated Hatschek process. Non-asbestos-fiber cement boards incorporating kraft and bamboo fibers were successfully produced in the laboratory using this innovative method based on Hatschek technology, with natural fibre addition in the range of 2–6 wt.%. Experimental results revealed that the Flexural strength and deflection of the board improved significantly, producing optimum values of 10.41 MPa and 2.0 mm, respectively for composite board reinforced with 10 wt.% and 6 wt.% of kraft pulp and bamboo fibers, respectively. The SEM morphology of the fractured surfaces revealed the mode of composite fracture as well as good interaction at the fiber–matrix interface. Overall, the mechanical properties of the developed composite boards satisfy the minimum requirements of relevant standards based on fiber cement flat sheets and can be employed for internal building applications in low-cost housing estates in developing countries. The outcome of this research indicates that the current industrial production process based on Hatschek technology can be employed for non-asbestos-fiber cement board production using the studied natural fiber. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate new materials from organosolv fibers, organosolv lignin, kraft fibers, and their blends. The organosolv fibers showed reprecipitated lignin on the surface, a comparably low fiber length of 0.565 mm on average, and a high fines content of 82.3%. Handsheets were formed and thermopressed at 175 °C and 50 MPa, yielding dense materials (1050–1100 kg/m3) with properties different to that of regular paper products. The thermopressing of organosolv fibers alone produced materials with similar or better tensile strength (σb = 18.6 MPa) and stiffness (E* = 2.8 GPa) to the softwood Kraft reference pulp (σb = 14.8 MPa, E* = 1.8 GPa). The surface morphology was also smoother with fewer cavities. As a result, the thermopressed organosolv fibers exhibited higher hydrophobicity (contact angle > 95°) and had the lowest overall water uptake. Combinations of Kraft fibers with organosolv fibers or organosolv lignin showed reduced wetting and a higher density than the Kraft fibers alone. Furthermore, the addition of organosolv lignin to Kraft fibers greatly improved tensile stiffness and strength (σb = 23.8 MPa, E* = 10.5 GPa), likely due to the lignin acting as a binder to the fiber network. In conclusion, new thermopressed materials were developed and tested, which show promising potential for sustainable fiber materials with improved water resistance. [ABSTRACT FROM AUTHOR]

Nowadays, the emphasis is on increasing the durability of all products. For this reason, it is also advisable to look into extending the durability of paper products. The main reason for using flax pulp is that flax and cotton pulp are widely used for the production of banknotes due to their higher strength. This paper deals with flax pulp with the addition of nanocellulose, which should further enhance the mechanical properties of the pulp. The tensile strength, breaking length, and tensile energy absorption index were evaluated as the key mechanical properties. At the same time, the effect of the addition of nanocellulose, whether it was added to the pulp mass or applied to the later produced paper as a spray or coating, was tested in comparison to paper without the addition of nanocellulose. The best mechanical properties, i.e., tensile strength, were achieved for the highest addition of 5% of nanocellulose into the pulp, at 24.3 Nm∙g−1, and for the coating application, at 28.7 Nm∙g−1, compared to the flax pulp without the addition, where the tensile strength was 20.5 Nm∙g−1. The results of this research are used for the assessment of nanocellulose as a natural compatible additive to enhance the strength properties of cellulose-based materials. [ABSTRACT FROM AUTHOR]

Itaconic acid (IA) is a value-added chemical currently produced by Aspergillus terreus from edible glucose and starch but not from inedible lignocellulosic biomass owing to the high sensitivity to fermentation inhibitors present in the hydrolysate of lignocellulosic biomass. To produce IA from lignocellulosic biomass, a gram-positive bacterium, Corynebacterium glutamicum, with a high tolerance to fermentation inhibitors was metabolically engineered to express a fusion protein composed of cis -aconitate decarboxylase from A. terreus responsible for IA formation from cis -aconitate and a maltose-binding protein (malE) from Escherichia coli. The codon-optimized cadA _ malE gene was expressed in C. glutamicum ATCC 13032, and the resulting recombinant strain produced IA from glucose. IA concentration increased 4.7-fold by the deletion of the ldh gene encoding lactate dehydrogenase. With the Δ ldh strain HKC2029, an 18-fold higher IA production was observed from enzymatic hydrolysate of kraft pulp as a model lignocellulosic biomass than from glucose (6.15 and 0.34 g/L, respectively). The enzymatic hydrolysate of kraft pulp contained various potential fermentation inhibitors involved in furan aldehydes, benzaldehydes, benzoic acids, cinnamic acid derivatives, and aliphatic acid. Whereas cinnamic acid derivatives severely inhibited IA production, furan aldehydes, benzoic acids, and aliphatic acid improved IA production at low concentrations. The present study suggests that lignocellulosic hydrolysate contains various potential fermentation inhibitors; however, some of them can serve as enhancers for microbial fermentation likely due to the changing of redox balance in the cell. [Display omitted] • Enzymatic hydrolysate of kraft pulp was used as a model lignocellulosic feedstock. • Kraft pulp hydrolysate enhanced itaconic acid (IA) production by recombinant C. glutamicum. • Some contaminants in kraft pulp hydrolysate improved IA production by recombinant C. glutamicum. [ABSTRACT FROM AUTHOR]

Kraft pulp (KP), an intermediate product obtained when wood chips are converted to paper, contains highly digestible fiber. This study evaluated the effect of KP inclusion in calf starters on growth performance, health, and plasma glucagon-like peptide 2 (GLP-2) concentration in calves. Twenty-five Holstein heifer calves were raised on a high plane of nutrition program using milk replacer containing 29% crude protein and 18% fat until 49 d after birth, and were fed calf starters containing KP at 0 (CON; n = 14) or 12% (KPS; n = 11) on a dry matter basis. All calves were fed the treatment calf starters and timothy hay ad libitum. Blood was collected at 4, 14, 21, 35, 49, 70, and 91 d after birth. Dry matter intake (DMI) of milk replacer and hay was not affected by treatment, whereas calf starter DMI was lower for KPS (0.93 kg/d) than for CON (1.03 kg/d). Higher neutral detergent fiber (NDF) content in KPS (31.7%) than in the CON starter (22.1%) resulted in higher NDF intake for KPS (0.55 kg/d) than for CON (0.47 kg/d). However, the consumption of starch was lower for KPS (0.29 kg/d) than for CON (0.33 kg/d). Despite the lower starter intake for KPS, body weight and average daily gain did not differ between treatments. No significant difference was observed in the plasma concentrations of metabolites, except for β-hydroxybutyrate (BHB); BHB concentration was lower for KPS (216 μmol/L) than for CON (257 μmol/L). The area under the curve for plasma GLP-2 concentration was higher for KPS (54.1 ng/mL × d) than for CON (36.0 ng/mL × d). Additionally, the fecal score postweaning (1.19 and 1.48 for KPS and CON, respectively) and the number of days that calves developed diarrhea throughout the experimental period (2.50 d and 8.10 d for KPS and CON, respectively) were lower for KPS than for CON. These results indicate that feeding KP reduces the severity and frequency of diarrhea without adversely affecting growth performance. This could be attributed to the increased plasma GLP-2 concentration induced by higher NDF intake. [ABSTRACT FROM AUTHOR]

Approaches to obtain nanocellulose have been extensively suggested, and among the most competitive methodologies includes mechanical defibrillation, which results in a nanocellulose gel suspension that can be used in a variety of applications. However, standard procedures results in inhomogeneous fibre sizes due to its physical approach. Pre-treatments have been suggested, such as enzymes, but their cost is a disadvantage. In this work, we suggest the use of cryoslash for bleach kraft pulp using a simple methodology of embedding the dry kraft pulp in distilled water following by freezing at −80 °C, which was slashed using a common blender and submitted to an ultra-fine friction grinder. Samples were studied at various grinding steps 5, 15, 30, 60 and 120. Overall, the energy difference required to defibrillate with cryoslash was ∼3.26 kWh/kg at 30 steps and ∼6 at 120 steps, which was similar to enzymatic pre-treatment with nanofibrils significantly smaller. Cryoslash presented a unique C–H in plane structure from nanocellulose, related to a decrease in average size of fibrils, while crystallinity and thermal properties of nanocellulose remained stable at 60 steps, but mechanical properties increased until 120 steps along with the transmittance values related to the energy consumption curve. [ABSTRACT FROM AUTHOR]

Oxidation of kraft pulp using hydrogen peroxide under mild acidic conditions can be applied in order to obtain new functionality of the fibres, in the form of carbonyl groups. The hydrogen peroxide concentration must, however, be higher than consumed by the oxidation reactions meaning that the liquid must be recirculated to fully utilize the hydrogen peroxide. This paper investigates the consequences of recirculation of the oxidation liquor. It was found that recirculation results in an accumulation of ions of transition metals (copper, iron and manganese) in the oxidation liquor. The transition metal ions are known for catalytic decomposition of hydrogen peroxide, producing radicals which may react with carbohydrates, forming carbonyl groups as well as causing carbohydrate degradation. This was confirmed through the recirculation of oxidation liquor as well as through controlled addition of transition metals. At high transition metal ion concentration the reactions were fast and a severe degradation of carbohydrates was observed, accompanied by a rapid hydrogen peroxide consumption. The consequence of this, in an industrial context, is that the concentration of metal ions must be carefully controlled in order to add functionality to the cellulose without causing excessive degradation of carbohydrates or consumption of hydrogen peroxide. [ABSTRACT FROM AUTHOR]

Xylanases can boost pulp bleachability in Elemental Chlorine Free (ECF) processes, but their industrial implementation for producing bleached kraft pulps is not straightforward. It requires enzymes to be active and stable at the extreme conditions of alkalinity and high temperature typical of this industrial process; most commercial enzymes are unable to withstand these conditions. In this work, a novel highly thermo and alkaline-tolerant xylanase from Pseudothermotoga thermarum was overproduced in E. coli and tested as a bleaching booster of hardwood kraft pulps to save chlorine dioxide (ClO2) during ECF bleaching. The extremozyme-stage (EXZ) was carried out at 90 °C and pH 10.5 and optimised at lab scale on an industrial oxygen-delignified eucalyptus pulp, enabling us to save 15% ClO2 to reach the mill brightness, and with no detrimental effect on paper properties. Then, the EXZ-assisted bleaching sequence was validated at pilot scale under industrial conditions, achieving 25% ClO2 savings and reducing the generation of organochlorinated compounds (AOX) by 18%, while maintaining pulp quality and papermaking properties. Technology reproducibility was confirmed with another industrial kraft pulp from a mix of hardwoods. The new enzymatic technology constitutes a realistic step towards environmentally friendly production of kraft pulps through industrial integration of biotechnology. [ABSTRACT FROM AUTHOR]

The objective of this study is to gain further insight into the compositional and physical changes of kraft pulp caused by oxidation with hydrogen peroxide under acidic conditions. A softwood kraft pulp has been subjected to varying degrees of oxidation. Changes in the composition, as well as resulting physical properties of laboratory sheets were investigated. Findings indicated that the oxidation resulted in an increased carbonyl group content, a decrease in intrinsic viscosity and a change in hemicellulose composition. The oxidized pulps were found to have a reduced water retention value and a slightly reduced tensile strength (4–11 % at the investigated conditions). However, a substantial increase in wet web tensile strength (6–23 %) and wet tensile strength (134–242 %) of the sheets was obtained. The sheets could easily be repulped and an increased wet strength maintained to a large extent, even after recycling of the sheets. [ABSTRACT FROM AUTHOR]

Cellulose nanofibrils (CNF) isolation based on a catalyst-free maleic anhydride esterification has proven to be effective, however, the effects of pulp hornification on CNF isolation by this strategy have yet to be explored, which could present significant impacts for CNF isolation. Herein, dried northern bleached softwood Kraft pulp (D-NBSK) and never-dried northern bleached softwood Kraft pulp (ND-NBSK) were selected as the substrates. After esterification with maleic anhydride (MA), the esterified ND-NBSK pulp (E-ND) shows a significantly smaller size and more fragmented structure than the esterified D-NBSK pulp (E-D). Meanwhile, higher degree of esterification can be realized for the never dried pulp as compared to the dried pulp, which is corroborated by the significantly stronger characteristic peaks of C O (1720 cm−1) and -COO− (1575 cm−1) from the FTIR spectra and the higher surface charge content (0.86 ± 0.04 mmol/g vs. 0.55 ± 0.05 mmol/g). A comparison of the characteristics of the resulting CNF similarly demonstrated the negative impact of hornification. Overall, this work indicates that hornification tends to reduce the accessibility of chemical reagents to the pulp, leading to insufficient deconstruction. Such negative impact of hornification should be considered when performing nanocellulose isolation, especially when using pulp as feedstock. [Display omitted] [ABSTRACT FROM AUTHOR]

The world demand for paper has been increased due to the increasing population Therefore, to cop up the limited wood fiber resources introducing raw material in pulp and paper industries is necessary. The aims of this study to evaluate the pulp and paper-making properties of Caesalpinia decapetela based on proximate chemical composition, fiber morphology, pulping, bleaching, and physical test of the final product. The results proximate chemical analysis showed that C. decapetela has holocellulose content of 78.14±0.1 % and lignin content 18.0±0.04 %. Fiber morphology revealed that the fibers were 0.708 mm long, 18.63 μm width, and have 5.1 μm cell wall thicknesses. Kraft pulping of C. decapetale, was performed at different active alkali (5 %, 10 %, 15 %, 20 % and 25 %) and temperature (150, 160 and 170 °C), keeping the sulphidity 25 % constant. The pulp maximum yield 44.1 % was obtained at active alkali content of 15 %, temperature 160 °C, and cooking time 90 minutes. The effect of pulping on fiber morphology was studied using scanning electron microscopy which showed the surface of fiber before pulping was tight, orderly arranged and the texture was relatively hard. After pulping, there was the removal of lignin, hemicellulose, and cellulose. Due to this fiber become soft loosened and contain micro-pores. Pulp produced was bleached, sheet preparation and testing were performed. The prepared paper sheets have a tensile index of 28.19 Nm/gm, burst index of 1.359 kPa m 2 / gm 1.359\hspace{0.1667em}\text{kPa}\hspace{0.1667em}{\text{m}^{2}}/\text{gm} , and tear indices of 4.2 mN m 2 / gm 4.2\hspace{0.1667em}\text{mN}\hspace{0.1667em}{\text{m}^{2}}/\text{gm}. This study concluded C. decapetale can be the new raw material for pulp and paper making industries. However, pilot plant studies are required to check this raw material for the full recommendation of the pulp and paper industries. [ABSTRACT FROM AUTHOR]

The demand for plastic packaging material has continued to increase worldwide, a phenomenon that had led to more negative impacts on the environment, especially waste pollution issues caused by the petrochemical industry producing plastics and polymers. As a result, this research aimed to study the production of biodegradable packaging by blending polylactic acid (PLA) and polybutylene succinate (PBS) with 5–20% (w/w) sweet bamboo (Dendrocalamus asper Backer) kraft pulp (SKP). Subsequently, several analyses were used to evaluate the biopolymer properties to determine if the composite could be used to produce biodegradable packaging. The addition of SKP 5% (w/w) provided the PLA/PBS composite with the highest thermal and mechanical properties. Furthermore, the effect of a plasticizer was studied by combining 5%, 10%, or 15% (w/w) Mesamoll in the PLA/PBS composite with 5% (w/w) SKP. This addition changed all composite properties and in particular provided good water vapor barrier properties. Finally, this research revealed that SKP plays a role as a nucleating agent in plasticized PLA/PBS composite. [ABSTRACT FROM AUTHOR]

This study aimed to determine the influence of prehydrolysis of wood chips on the kraft pulping of Populus x euramericana. Optimum cooking conditions were determined by evaluating different alkali concentrations and cooking periods. Xylanase was used to hydrolyze chips before cooking. Prehydrolysis process increased the yield and viscosity of pulp. Consequently, the mechanical properties of paper changed remarkably. In contrast, the optical properties of the unbleached kraft pulp declined due to lignin content. [ABSTRACT FROM AUTHOR]

In this work, we prepared novel cellulosic paper by incorporating tannin into the kraft pulp for potential application in active food packaging. The kraft pulp fibers were firstly periodate oxidized to obtain the dialdehyde cellulosic fibers, and then reacted with varied dosages of tannin to incorporate them into the fibers by covalent bondings between aldehyde groups on cellulose and active hydrogen on tannin. Handsheets were prepared using the tannin incorporated fibers through papermaking process and the properties were characterized. The percentage of tannin in the paper increased with the increase of the tannin dosage. FT-IR spectra confirmed the successful incorporation of tannin into the cellulosic fibers. It was found that paper after incorporation of tannin turned to be surface hydrophobic with contact angles higher than 90°, which may probably due to the covalent bonds between tannin and cellulose. The handsheets show high antioxidative and UV-shielding properties, which both increased with the increase of the tannin percentage in the paper. Water vapor transmission rate (WVTR) decreased after the incorporation of tannin, and this could facilitate its application in food packaging. The breaking length of tannin incorporated paper decreased insignificantly, less than 10% with the tannin percentage as high as 45%. Unlabelled Image • Tannin were incorporated into the kraft fibers through covalent bondings. • Paper handsheets were prepared using tannin incorporated kraft fibers. • Paper with tannin exhibited high UV-shielding and antioxidative properties. • Its hydrophobicity and water vapor barrier property were improved. [ABSTRACT FROM AUTHOR]

The delignification of kraft pulp with sodium dithionite was studied to remove lignin content in the pulp. The sodium dithionite dissolves the chromophoric groups and residual lignin present in the pulp. The increase in dosage of sodium dithionite and reaction temperature of delignification has positive effect on kappa reduction of pulp. X ray diffraction was used to determine the crystallinity index of bleached pulp. The crystallinity increased from 83.3% for unbleached pulp to 86.7% after delignification. Fourier transform infrared spectroscopy shows the reduction in hydrogen bonding in bleached pulp and also the conversion of cellulose I to cellulose II. FT-Raman spectra shows that the fluorescence observed in the spectra of unbleached pulp reduced significantly in comparison to the spectra of bleached pulp resulting in removal of residual lignin and chromophoric groups present in the pulp. Scanning electron imaging shows the smoothening of fiber surface after bleaching. The delignification reaction followed first-order kinetics and activation energy is 33.57kJ/mol. [ABSTRACT FROM AUTHOR]

The first goal of this study was to determine the polysaccharide composition of Pinus brutia wood and how this composition changes during kraft pulping. The second goal was to determine the effect of the stem height on chemical composition. The content of hemicelluloses was about 280 mg/g at a height of 1.3 m, whereas the content was about 300 mg/g at the top of the stem (4.3 m). The main sugars in the wood of P. brutia were mannose (102 mg/g dw), xylose (69 mg/g dw), and glucose (44 mg/g dw). During kraft pulping, 52% of the total hemicelluloses were degraded. Glucose and xylose were more stable than mannose. The total amounts of cellulose in the wood and in the kraft pulp of P. brutia were determined to be 330 mg/g and 661 mg/g, respectively, at 1.3 m. [ABSTRACT FROM AUTHOR]

Recently, a new type of bleaching sequence, Elemental Chlorine Free (ECF) light with one D stage, has been developed. It combines the efficiency and high selectivity of chlorine dioxide (ClO2) bleaching with more environmental friendly oxygen based bleaching chemicals. This work examines the effect of pH on the formation of adsorbable organically bound halogens (AOX) in an intermediate D stage – a single ClO2 stage at the middle of an ECF light bleaching sequence. Carbon dioxide (CO2) is used to generate a bicarbonate buffer in situ, stabilizing the pH during the bleaching. Near-neutral pH is hypothesized to decrease the formation of strongly chlorinating species, so that the AOX formation is reduced. The results indicate that a near-neutral pH D stage can reduce the AOX content in the effluents with up to 30%. The ISO brightness was unchanged to a lower ClO2 consumption. The pulp viscosity was slightly higher after near-neutral pH D stage, but to its disadvantage a lesser delignification and removal of HexA was obtained. The degradation of HexA correlated well with the AOX, affirming earlier theories that HexA has a major impact on the AOX formation. The higher amounts of residual HexA and lignin resulted in more thermal yellowing of the pulps bleached with a near-neutral pH D stage. [ABSTRACT FROM AUTHOR]

Enzymatic hydrolysis processes can change the physical characteristics of nanocellulose derived from Kraft pulp. Among these attributes are its crystallinity index and dimensions. In this study, we determined the optimal conditions under which nanocellulose could be produced enzymatically with the greatest increase of the crystallinity index relative to its initial state. Application of Central Composite Rotatable Design statistical analysis to the experiments was employed to direct an increase the crystallinity index in 10% at the 24‐H hydrolysis time. Upon establishment of ideal levels of starting material and enzyme, reactions were carried out at hydrolysis times of 24, 48, and 72 H under these ideal parameters. The effectiveness of deagglomeration was demonstrated by measuring the hydrodynamic diameter of the particles by dynamic light scattering. Scanning electron microscopy was performed on four samples, the original material, kraft pulp, and hydrolyzed biomaterials at 72 H in the ideal parameters. The hydrolyzed material with the best statistical data, revealing a fiber diameter of 180 nm, disclosing to be biomaterial with nanocellulose dimensions. [ABSTRACT FROM AUTHOR]

The authors explored the possibility of using persimmon byproducts as raw materials for obtaining kraft pulps. Various unbleached and bleached kraft pulps via pulping and bleaching processes were prepared. Then, their characteristics were determined and compared with those of commercial kraft pulps. For the highest screened yield of persimmon byproduct unbleached kraft pulps, the optimal pulping conditions were a liquid ratio of 5:1, an active alkali concentration of 25%, a sulfidity of 30%, and a cooking time of 3 h. Furthermore, the authors obtained persimmon byproduct bleached kraft pulps (PB-BKPs) with an ISO brightness of 73% via three-stage bleaching using 3% ClO2, 1.5% NaOH, and 3.5% ClO2. Moreover, PB-BKP prepared under optimal pulping and bleaching conditions had physical characteristics similar to those of commercial mixed-hardwood bleached kraft pulp, but with relatively low ISO brightness. Therefore, as raw materials, persimmon byproducts can be used for manufacturing a bleached kraft pulp. [ABSTRACT FROM AUTHOR]

In the current work, cellulose nanofibers (CNF) were isolated from unbleached kraft pulps of date palm fruit stalks (DPFS) and date palm rachis (DPR) residues by ultrafine grinding. The isolated CNF were characterized by high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), zeta potential measurement, tensile strength properties, contact angle, as well as oil-proof testing. The CNF were applied as a coating material for cardboard paper sheets made from unbleached kraft DPFS and DPR pulps. The results showed that CNF from DPFS and DPR had close dimensions (4–14 nm in width and several microns in length) but their zeta potential was different (−44.65 eV and −51.46 eV for CNF from DPFS and DPR pulps, respectively), as well as their crystallinity (79.4% and 75.5% for CNF from DPFS and DPR pulps, respectively). CNF films from DPFS had tensile stress and Young's modulus of 113.3 MPa and 3.81 GPa, respectively, while those from DPR had tensile stress and Young's modulus of 71.0 MPa and 2.93 GPa, respectively. Films from DPFS CNF showed lower hydrophilicity than that from DPR, nevertheless excellent oil-proof property was obtained in both kinds of films. Coating of cardboard sheets prepared from unbleached kraft DPFS and DPR pulps with CNF layer of about 7-µm thickness resulted in significant changes in some physical properties of paper sheets, such as decreasing their air permeability, water vapor transmission rate, and water absorption; both kinds of CNF imparted paper sheets good oil-proof properties. CNF coating also imparted paper sheets remarkable wet tensile strength properties. The results showed the feasibility of utilizing date palm wastes in producing CNF films with distinct properties from low-cost unbleached kraft pulp, as well as using these CNF as a multi-functional coating material in papermaking industry. • Cellulose nanofibers (CNF) were isolated from unbleached date palm pulps. • The properties of CNF were dependent on the date palm residue used. • CNF films had excellent oil-proof and good mechanical properties. • CNF were successfully used for coating cardboard sheets. • CNF coating improved wet strength, air, oil, and moisture barrier properties. [ABSTRACT FROM AUTHOR]

Increasing global demands on pulp and paper necessitate fast-growing pulpwood. Sesbania grandiflora is one of the related species on which there is little scientific information. This research examines the potential of S. grandiflora as pulpwood by studying the effects of beating on pulp derived from S. grandiflora. Kraft pulp was prepared and beaten at 10000 and 20000 revolutions. Handsheets with the target grammage of 60 g/m² were produced. Pulp properties and physical and mechanical properties of handsheets were evaluated according to the TAPPI standard. Tensile index, tear index, bursting index, and folding endurance of handsheet made from S. grandiflora pulp increased with an increase in beating revolutions. Its moderate strength properties were due to its short fiber length. The study concludes that the pulp derived from S. grandiflora is not suitable to produce heavy duty paper. [ABSTRACT FROM AUTHOR]

Leucaena leucocephala and Casuarina equisetifolia are two fast-growing deciduous tropical hardwoods that were characterized for their morphological and chemical characteristics to assess their suitability for pulp production. The effects of kraft pulping sulfidity, cooking time, and cooking temperature on screened pulp yield and Kappa number were studied. Handsheets made from these pulps showed a vessel picking problem during printing that was reduced by treating the pulp with 0.1% cellulase and beating the pulp at high consistency. [ABSTRACT FROM AUTHOR]

Abstract The electrostatic precipitators ash leachate (EPAL) from recovery boilers of kraft pulp mills is generated in processes dedicated to the removal of potassium and chloride salts seeking to avoid fouling and corrosion in pipes and equipment. However, the EPAL is rich in salts and has high electrical conductivity. Whenever it is sent to the effluent treatment plant (ETP), it can cause negative impacts to the biological process. It may jeopardize particularly the microbial community and the sludge bio-flocculation, causing sludge losses in the secondary clarifiers, reducing the overall efficiency of the effluent treatment plant. The objective of this research was to evaluate the influence of EPAL from the recovery boilers added to a typical effluent from a bleached eucalyptus kraft pulp mill in gradually increased doses and in sudden doses (shock loads) in the efficiency of the biological treatment. Three biological sequential batch reactors (R1, R2, R3) with a volume of 1000 ml each were tested. The Reactor R1 was operated as a reference and fed only with typical effluent from the pulp mill; Reactor R2 was fed with mill effluent with gradually increased doses of EPAL in fixed proportions until reaching a real industrial condition; Reactor R3 was fed with mill effluent and with sudden doses of EPAL. The reactors were operated in similar conditions, i.e., the concentration of dissolved oxygen (DO) was always kept higher than 2 mg L−1, COD:N:P ratio equal to 250:5:1 and hydraulic retention time of 12 h. Depending on the dose which was applied, the EPAL inhibited microbiological activity, reduced the efficiency of COD removal of the biological treatment (10% when EPAL was gradually applied and 15% in sudden doses) and increased the sludge carryover in the sedimentation phase (148% when EPAL was gradually applied and 170% in sudden dosages). Furthermore, the reduced efficiency and suspended solid carryover were more significant when sudden doses were applied compared to the application of gradual doses of the EPAL. Graphical abstract Unlabelled Image Highlights • Kraft pulp mill electrostatic precipitator ash leachate (EPAL) has a high salinity. • EPAL negatively affects biosludge formation in the effluent biotreatment. • COD removal decreased by 10% when EPAL was gradually applied and 15% in sudden doses. • TSS carryover increased by 148% when EPAL was gradually applied and 170% in sudden doses. [ABSTRACT FROM AUTHOR]

The effect of wood kraft pulp (KP) feed on dietary digestibility, ruminal fluid pH, rumen fermentation characteristics, and milk production performance in lactating dairy cows was examined. Four lactating dairy cows were used for the feeding experiment by the cross‐over design. The control group and KP group were set up as treatments. The control group was fed total mixed ration (TMR) (40% roughage and 60% concentrate) and the KP group was fed TMR containing 12% KP that replaced half of the rolled corn in the control diet. The dry matter intake, digestibility of the feed components, and milk yield were not significantly different between control group and KP group. The number of times that the ruminal fluid pH was below 6.1 tended to decrease in the KP group compared to the control group (p < 0.10). The acetic acid ratio in the ruminal fluid of the KP group increased compared to the control group (p < 0.05) and the propionic acid ratio in the ruminal fluid of the KP group decreased compared to the control group (p < 0.05). The acetate:propionate acid ratio was increased in the KP group compared with the control group (p < 0.05). Lipopolysaccharide levels in the ruminal fluid of the KP group tended to decrease compared to the control group (p < 0.10). Based on these results, it was indicated that the use of KP feed for lactating dairy cows induced the same rumen fermentation characteristics as those in cows given a large amount of roughage without depressing milk productivity. Therefore, KP could be a valuable feed resource substitute for grains, which would also reduce the risk for subacute rumen acidosis. [ABSTRACT FROM AUTHOR]

Abstract Xylanase extract, produced by T. reesei QM9414 in a culture with sugarcane straw (SS) as substrate, was studied in the biobleaching of Kraft pulp associated with chemical bleaching. The biobleaching parameters optimization showed that 30 U/g of xylanases, at pH 5, at 50 °C, during 30 min, are the best conditions to bleach the crude Kraft pulp (3% of consistency). lA decrease of 12.5% of Kappa number, as well as the release of 1 g/lL of sugar, and the presence of chromophores compounds (237 nm) are also observed. After this xylanase biobleaching the final chlorine dioxide consumption decrease in 10%, maintaining the same brightness as in the control on the subsequent chemical process. SEM shows the effect on the pulp surface. These results clearly demonstrated that the T. reesei QM9414 xylanase is an eco-friendly and economical alternative for paper production. Highlights • Xylanase production by T. reesei QM9414 using sugarcane straw residue as carbon source. • Kraft pulp biobleaching (30 U/g of T. reesei QM9414 xylanases, in pH 5, at 50 °C, during 30 min) resulted in a decrease of 12.5% of Kappa number. • Decrease of chlorine dioxide (ClO 2) consumption, 10%, in chemical bleaching. • Images by SEM prove the effective enzyme action on Kraft pulp surface. [ABSTRACT FROM AUTHOR]

This paper compares the acid and enzymatic hydrolysis in relation to bioethanol production. The pulp obtained from wood of the fast-growing poplar species (Populus deltoides x maximowiczii and Populus trichocarpa Torr. & A. Gray ex Hook) was used as a feedstock. The delignification process by the Kraft method was carried out with 19% and 26% of active alkali (NaOH and Na2S). The obtained sugars (xylose and glucose) were analyzed by a high-performance liquid chromatography. The results concluded that the enzymatic hydrolysis process is better than acid hydrolysis because a higher content of sugars (especially xylose) was obtained. Additionally, after the acid and enzymatic hydrolysis process from Populus trichocarpa pulp, more sugars were obtained than from the pulp of Populus deltoides × maximowiczii. The Kraft pulp from the wood of fast-growing poplar species is a good raw material for the production of glucose. However, in order to obtain a higher xylose content and finally increase the profitability of bioethanol production, a new method should be developed, or the Kraft method should be optimized. [ABSTRACT FROM AUTHOR]

Abstract The aim of this research was to fabricate multilayer insulator nanocomposites using phenolic resin impregnated bacterial cellulose (BC) handsheets and investigate the relationships between their structural and electro-thermo-mechanical properties. G. xylinus was incubated in a static Hestrin-Schramm culture at 28 °C for 14 days. Then, BC aqueous suspension was added to kraft pulp aqueous suspension. The content of BC that was added to the pulp suspension was as follows: 5, 10 and 15%. The disintegrated BC was turned into handsheets by a vacuum method. Dried handsheets were immersed in phenolic resin. To obtain composites, 5 immersed handsheets from each treatment were laid-up and hot pressed at 150 °C under 100 MPa pressure for 10 min. The specimens were characterized by means of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermal mechanical analysis (TMA), field-emission scanning electron microscopy (FE-SEM) techniques and insulating tests as dielectric loss factor and breakdown voltage. The results of thermal analysis showed an improvement in the thermal stability and an increase in the evaporation enthalpy of prepared samples with higher BC content. The mechanical examinations indicated that by increasing BC content in nanocomposites, the loss modulus and tan delta increased and the storage modulus of specimens decreased. The coefficient of thermal expansion (CTE) of samples diminished with increase of BC content. FE-SEM characterization showed different qualities of resin impregnation of the papers. The results of insulating tests confirmed that dielectric loss tangent and dielectric breakdown voltage increased in the specimens with higher BC content. [ABSTRACT FROM AUTHOR]

To meet the demand for carbon-fibre-reinforced composites in lightweight applications, cost-efficient processing and new raw materials are sought for. Cellulose and kraft lignin are each interesting renewables for this purpose due to their high availability. The molecular order of cellulose is an excellent property, as is the high carbon content of lignin. By co-processing cellulose and lignin, the advantages of these macromolecules are synergistic for producing carbon fibre (CF) of commercial grade in high yields. CFs were prepared from precursor fibres (PFs) made from 70:30 blends of softwood kraft lignin (SW-KL) and cellulose by dry-jet wet spinning with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]) as a solvent. In focus was the impact of the molecular mass of lignin and the type of cellulose source on the CF yield and properties, while membrane-filtrated kraft lignin and cellulose from dissolving kraft pulp and fully bleached paper-grade SW-KP (kraft pulp) served as sources. Under the investigated conditions, the yield increased from around 22% for CF from neat cellulose to about 40% in the presence of lignin, irrespective of the type of SW-KL. The yield increment was also higher relative to the theoretical one for CF made from blends (69%) compared to those made from neat celluloses (48–51%). No difference in the mechanical properties of the produced CF was observed. [ABSTRACT FROM AUTHOR]

Inorganic fillers are usually used in papermaking industry to reduce production costs and enhance paper optical properties. As an attempt to improve fillers application in papermaking, carboxymethyl cellulose (CMC) and poly aluminum chloride (PAC) were used to encapsulate precipitated calcium carbonate (PCC) filler and modify its surfaces. In the first step, the optimum conditions for filler treatment (i.e. pH, CMC and PAC contents) were obtained. Through the second step, different amounts of CMCencapsulated PCC were added to fiber suspension and some hand-sheets were made. Then, the effect of modified filler addition in different levels of 20, 25, and 35% on mechanical and optical properties of paper was investigated. The PAC dosage was found to be a critical factor for effective encapsulation of PCC fillers by carboxymethyl cellulose. When the dosages of CMC and PAC were 4% and 0.8% (based on the dry weight of PCC), respectively, filler modification caused to improve significantly the retention by more than twice. Strength properties of the hand-sheets fabricated with the CMC/PAC-modified PCC were also found to be significantly better than those obtained with the unmodified PCC at similar levels of filler content. In addition, the brightness and opacity of the filled papers at 30% addition of CMC-modified fillers were strikingly enhanced to 88,45 and 77%, respectively. SEM observations of the filled papers also demonstrated that CMC-encapsulated filler particles were clustered and retained efficiently onto the fiber network. The present method for modification of PCC may provide an alternative approach to increase the filler amount in the paper structure by alleviating filler drawbacks. [ABSTRACT FROM AUTHOR]

Bacterial infections and surface contaminations are worrying public health issues. It becomes urgent to find solutions. One of the ways to limit bacterial proliferation is to develop new antimicrobial materials. The phenolic compounds of essential oils like thymol and carvacrol, are attractive antibacterial candidates, which have gained great popularity in the food, cosmetic, and pharmaceutical industries. This work describes the elaboration of bioinspired antibacterial materials. Thymol and carvacrol are linked to kraft pulp fibers, via triazine link. This novel material has been investigated for its antibacterial properties against Escherichia coli and Staphylococcus aureus. The developed materials show very interesting antibacterial activity. The grafting of thymol and carvacrol by covalent bond allows to avoid the problem of their release and, thus, could maintain the antibacterial properties of support. [ABSTRACT FROM AUTHOR]

In present study, single and consecutive applications of xylanase and lignin peroxidase were performed in an XOQP TCF sequence to bleach pine and eucalypts kraft pulp. The consecutive use of Geobacillus sp. strain 71 xylanase and Rhodococcus jostii RHA1 lignin peroxidase was more effective than the single uses. XyzGeo71 treatment (X) indicates a 9,76% and 28,52% reduction in kappa number for pine and eucalypts kraft pulps, respectively. LiPRHA1 treatment (X) showed a 7,88% and 20,9% reduction a in kappa number for pine and eucalypts kraft pulps, respectively. The consecutive treatment of XyzGeo71 and LiPRHA1 (X), however, indicated a 13,67% and 37,2% reduction in kappa number for pine and eucalypts kraft pulps, respectively. The results showed that delignification with the consecutive xylanase and lignin peroxidase treatment was very significant. [ABSTRACT FROM AUTHOR]

In this work, a fundamental understanding of oxygen delignification distracted by dissolved lignin was investigated. In the new biorefinery model of shortening kraft pulping integrated with extended oxygen delignification process, increasing content of residual lignin in the original pulp could result in enhanced delignification efficiency, higher pulp viscosity and less carbonyl groups. However, the invalid oxygen consumption by dissolved lignin could be increased with the increase of process temperature and alkali dosage. The normalized ultraviolet absorbance (divided by absorbance at 280 nm) also showed that the content of chromophoric group in dissolved lignin decreased with oxygen delignification proceeded, both of which indicated that dissolved lignin could enhance the invalid oxygen consumption. Therefore, a conclusion that replacement of the liquor at the initial phase of oxygen delignification process would balance the enhancement of delignification efficiency and invalid oxygen consumption was achieved. [ABSTRACT FROM AUTHOR]

Moisture sorption and moisture sorption hysteresis of carbohydrates are phenomena which affect the utilisation of products made thereof. Although extensively studied, there is still no consensus regarding the mechanisms behind sorption hysteresis. Attempts have been made to link the behaviour to molecular properties, in particular to softening properties, and the moisture sorption hysteresis has therefore here been investigated by modifying cellulosic fibres to affect their softening properties. The results show that the moisture sorption hysteresis diminishes with decreasing softening temperature, and was even completely absent at the higher degrees of modification. The moisture sorption characteristics also changed from a type II sorption to a more type III sorption behaviour, a feature more prominent the higher the degree of modification and the higher the temperature. For the highest degree of modification studied the sorption characteristics changed from sorbing less water the higher the temperature to sorbing more water with increasing temperature. [ABSTRACT FROM AUTHOR]

Fully dissolved cellulose samples are a requirement for reliable size exclusion chromatography (SEC). Although most of the standard dissolving pulps can be completely dissolved in the N,N- dimethylacetamide/lithium chloride (DMAc/LiCl) solvent system, some cellulose samples (e.g., regenerated cellulose fibers) have poor solubility and therefore have a limited access to molar mass measurements. For improving the latter, different activation steps have been developed. In order to obtain complete solutions for subsequent SEC analysis, the scope of this study was to further improve established methods by elucidating the major influential factors of sample preparation. In addition, the degree of stretching in artificial fibers was examined for viscose fibers. Therefore, activation steps in DMAc or dimethyl sulfoxide (DMSO) and subsequent dissolution in DMAc/LiCl were analyzed with swelling and dissolution kinetics. The time needed for maximum swelling was found to be the optimum activation time. Turbidity measurement was introduced to observe dissolution kinetics as an indicator of dissolution quality. Thus, the duration, as well as the number of steps toward dissolution, was optimized to enhance the throughput in the overall analysis of a large variety of hitherto poorly soluble cellulose samples. A comparison of the MMDs of completely soluble reference materials obtained with the intensified conventional method, and the developed method demonstrated that the latter has no adverse influence on the results. [ABSTRACT FROM AUTHOR]

Although biological pretreatment of cellulosic fiber based on endoglucanases has shown some promise to facilitate cellulose nanofibrillation, its efficacy is still limited. In this study, a xylanase-aided endoglucanase pretreatment was assessed on the bleached hardwood and softwood Kraft pulps to facilitate the downstream cellulose nanofibrillation. Four commercial xylanase preparations were compared and the changes of major fiber physicochemical characteristics such as cellulose/hemicellulose content, gross fiber properties, fiber morphologies, cellulose accessibility/degree of polymerization (DP)/crystallinity were systematically evaluated before and after enzymatic pretreatment. It showed that the synergistic cooperation between endoglucanase and certain xylanase (Biobrite) could efficiently “open up” the hardwood Kraft pulp with limited carbohydrates degradation (<7%), which greatly facilitated the downstream cellulose nanofibrillation during mild sonication process (90 Wh) with more uniform disintegrated nanofibril products (50–150 nm, as assessed by scanning electron microscopy and UV–vis spectroscopy). [ABSTRACT FROM AUTHOR]

Caffeic acid (3,4-dihydroxycinnamic acid) serves as a building block for thermoplastics and a precursor for biologically active compounds and was recently produced from glucose by microbial fermentation. To produce caffeic acid from inedible cellulose, separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) reactions were compared using kraft pulp as lignocellulosic feedstock. Here, a tyrosine-overproducing Escherichia coli strain was metabolically engineered to produce caffeic acid from glucose by introducing the genes encoding a 4-hydroxyphenyllactate 3-hydroxylase ( hpaBC) from Pseudomonas aeruginosa and tyrosine ammonia lyase ( fevV) from Streptomyces sp. WK-5344. Using the resulting recombinant strain, the maximum yield of caffeic acid in SSF (233 mg/L) far exceeded that by SHF (37.9 mg/L). In the SSF with low cellulase loads (≤2.5 filter paper unit/g glucan), caffeic acid production was markedly increased, while almost no glucose accumulation was detected, indicating that the E. coli cells experienced glucose limitation in this culture condition. Caffeic acid yield was also negatively correlated with the glucose concentration in the fermentation medium. In SHF, the formation of by-product acetate and the accumulation of potential fermentation inhibitors increased significantly with kraft pulp hydrolysate than filter paper hydrolysate. The combination of these inhibitors had synergistic effects on caffeic acid fermentation at low concentrations. With lower loads of cellulase in SSF, less potential fermentation inhibitors (furfural, 5-hydroxymethyfurfural, and 4-hydroxylbenzoic acid) accumulated in the medium. These observations suggest that glucose limitation in SSF is crucial for improving caffeic acid yield, owing to reduced by-product formation and fermentation inhibitor accumulation. [ABSTRACT FROM AUTHOR]

Bioenergy, including energy from wood, currently provides about 9-13% of the total global energy supply. Every fibre of fast-growing wood has a value for its potential use as a material in both pulp and paper and wood chemical industries. The aim of this study was to assess the chemical composition and fibre's properties of fastgrowing species in Latvia - aspen, hybrid aspen, lodgepole pine, poplar and willow. Results showed a variation of cellulose, lignin, extractives and ash contents among the species. Kraft pulp yield and amount of residual lignin were measured and properties of pulp fibres determined. Form factor and fine content in pulp were measured. Poplar and aspen wood had the highest content of cellulose, while lodgepole pine had the highest lignin content in wood and the longest kraft pulp fibres. Willow had 20% of fines in pulp. Individual results suggest the most suitable application of each species. [ABSTRACT FROM AUTHOR]

In this study, we have extracted and bleached fibers from three plants (Typha latifolia, Agave americana, and Pennisetum alopecuroides). The obtained pulp contains more than 50% of fines and fibers with lengths not exceeding 1 mm. Generally, the amount of fines depends on fiber source, fiber morphology, pulping conditions, and the extent of mechanical treatment. Handsheets were produced with plant fibers alone or mixed (in different percentages: 7.5%, 15%, 22.5%, and 30%) with a commercial kraft pulp. The mechanical and optical properties of the sheets (breaking length, tear index, young modulus, whiteness, and opacity) show that plants could be used as a substitute fiber supply for the paper industry. However, fines were hardly retained in the sheets. A model to explain the removal of fines is proposed. [ABSTRACT FROM AUTHOR]

A part of kraft lignin (KL) can be used as a valueadded product without detracting the chemical recovery and the energy balance of the kraft mill. The focus of this study is the production of light-weight carbon fibres (CFs) from KL obtained by the LignoBoost process. For this purpose, crude KL and various cellulose products from kraft pulping of hardwood (HW) and softwood (SW) were dissolved in 1-ethyl-3-methylimidazolium acetate ([EMIm] [OAc]) and submitted to dry-jet wet-spun to obtain precursor fibres containing 70% KL and 30% cellulose, which were thermally stabilised and further converted by thermal treatments into CF. The initial and final products were characterised with respect to, e.g. mole mass distribution, thermal properties, tensile strength and tensile modulus determination. The optimised precursor fibres are smooth and flexible with similar mechanical properties as commercial textile fibres. The best CFs made had a tensile strength of 780 MPa and a tensile modulus of 68 GPa and are thus stronger and stiffer than those produced by meltspinning of SW-based lignins alone. The new CFs based on dry-jet wet-spun precursors still have a high potential for further improvements. [ABSTRACT FROM AUTHOR]

The catalytic and non-catalytic fast pyrolysis process for converting Kraft pulp paper waste into bio-oil and biochar was studied. Catalysis free pyrolysis of untreated Kraft pulp resulted on good yields of bio-oil (39% at 400 °C), showing a relative high concentration of levoglucosan, while phosphoric acid-pretreated pulp produced lower yields of bio-oil (max. value 14% at 350 °C) being levoglucosenone the main component. The catalytic pyrolysis of pretreated pulp employing silica led to a high yield of the liquid fraction (57% at 400 °C) with a high selectivity to levoglucosan. The biochar produced from as received pulp could be envisaged for soil amendment. It displayed a relatively high specific surface area, showing micro and mesoporosity. Besides, no phytotoxic effect of the biochar obtained at 350 °C was recorded. [ABSTRACT FROM AUTHOR]

This study focused on the use of industrialeucalyptus globulusbark as an alternative fiber source for bleached pulp and paper production. Bark has high extractives and ash contents (7.7% and 3.5%, respectively) but a mild hydrothermal pretreatment was tested, decreasing its values to 2.8% and 2.4%, respectively. Untreated and pretreated bark were kraft pulped at 15% and 20% (as Na2O) active alkali conditions. The pretreatment improved delignification when using low active alkali; kappa number 25.4 vs 17.5, and shives 3.1% vs 0%, respectively, with untreated and pretreated bark. The pretreatment resulted in a lower chemical demand to obtain pulps with similar yield and kappa number. It was possible to produce bleached pulps with good handsheet optical, physical, and mechanical properties with slightly lower values than those of industrial eucalypt wood pulps; e.g., brightness > 85% vs 87%, tear index > 4.2 vs 5.6 mn.m2.g−1, tensile index > 62 vs 69 n.m.g−1for bark and wood pulps, respectively. [ABSTRACT FROM AUTHOR]

Pulp mills constantly look for opportunities to increase their production capacity without major investments, as well as to save in overall bleaching costs. Peracetic acid (PAA) is used in post bleaching of kraft pulps to increase pulp brightness, to prevent brightness reversion in pulp storage, and to prohibit problems caused by extractives. However, the rates and significance of reactions between PAA and lipophilic extractives in pulp bleaching are not known in detail. Hence, the reactions between PAA and model compounds of extractives have been studied as emulsions in water and directly in methyl- tert-butyl ether (MTBE). Unsaturated compounds were found to be reactive in both water and MTBE, and the conventional extractive analyses had to be modified. Freeze-drying the reaction mixture with subsequent trimethylsilylation and GC-analysis was a very effective analytical approach. As a result of PAA treatment, fatty acids and sterols with double bonds were shown to form epoxides and the corresponding diols. Dehydroabietic acid (DeAb) also reacted with PAA by oxidation of the benzylic position. After longer reaction times, the reaction products of the extractives were further degraded or formed cross-linked aggregates. The epoxides and diols were also identified in samples from pulp mills applying PAA in post bleaching. [ABSTRACT FROM AUTHOR]

The progress of the conversion, the yield, the structure and the morphology of the produced carbonaceous materials as a function of time were systematically studied with pyrolysis-GC/FID and FESEM microscope. The conversion of galactoglucomannan, bleached kraft pulp and TEMPO oxidized cellulose nanofibrils followed the reaction route of glucose being slower though with fibrous material, higher molar mass and viscosity. The conversion of kraft lignin was minor following completely different reaction route. Carbonaceous particles of different shape and size were produced with yields between 23% and 73% after 4 h with being higher for lignin than carbohydrates. According to the results, potential pulp mill streams represent lignocellulosic resources for generation of carbonaceous materials. [ABSTRACT FROM AUTHOR]

In the first stage of pulp bleaching, the quantity of added chemicals (ClO2 and/or Cl2) is commonly controlled by kappa factor, based on a kappa number online analyzer together with a compensated brightness control scheme as a feedback strategy. However, a kappa number analyzer is not always available, so the bleaching quality relies heavily on the chemical dosage set-point chosen by the operators. In this study, an improved model for the chlorination stage brightness optimization was proposed, based on brightness and residual chemicals before pulp enters the bleaching tower. Additionally, the experience of operators of (C95/D5) bleaching was employed in order to find an optimum chemical dosage setpoint quickly. The golden section search algorithm (i.e., '0.618 method') was used to find the optimum chemical dosage in this paper. After applying the proposed method in a pulp mill (C95/D5) bleaching stage, the chlorination stage brightness shifted from 62.9% ISO to the target value 60.7% ISO. Meanwhile, the standard deviation was reduced from 3.0 to 2.5. [ABSTRACT FROM AUTHOR]