Pulp Fibers Research Articles

Characterization of heat- and alkali-resistant feruloyl esterase from Humicola insolens and application in the production of high-strength kraft straws.

The application of feruloyl esterase (FAE) in biobleaching can effectively hydrolyze the feruloyl ester bond between hemicellulose and lignin, thereby partially disrupting the dense structure of the fiber, reducing the use of chemical reagents, and obtaining high-performance pulp fibers. Here, we successfully expressed the thermostable alkaline feruloyl esterase from Humicola insolens (H. insolens) in Pichia pastoris GS115, with an enzyme activity yield of 2.36 ± 0.21U/mL. The highest activity of FAE for the hydrolysis of ethyl ferulate was observed at pH7.5 and 70°C. It retained about 56% of its maximum activity in the pH range of 11.0. After being incubated at 50-55°C for 1h, it retained 70.05% of its maximum activity. The addition of bio-enzyme pretreatment before chemical bleaching can reduce chemical reagents by 20%, result in a 10.64% reduction in kappa value, and increase the delignification rate of the pulp by 6.36%. In addition, the surface of the enzyme-treated pulp showed rougher broom-like fiber filaments, and the viscosity of the enzyme-pretreated pulp (ECP) before chemical treatment increased by 131.51% compared to the chemically treated pulp (CP), further indicating that the enzyme-pretreated pulp had higher pulp strength.

Innovative fabrication of eco-friendly bio-based foam from sugarcane bagasse and sodium alginate with enhanced properties and sustainable applications for plastic replacement

Foam materials possess notable features, including low density, high porosity, low thermal conductivity, and high impact resistance, making them extensively used in various sectors such as construction, transportation, water treatment, and packaging. However, the majority of commercial foam materials are derived from synthetic polymers based on fossil fuels, which raises concerns regarding health and ecology. In this work, we present a straightforward and scalable approach (physical cross-linking and common pressure drying) for fabricating a bio-based foam material using pulp fibers sourced from discarded sugarcane bagasse and sodium alginate extracted from seaweed. The resulting foam material exhibits low density (13.7–20.5 kg/m3), exceptional thermal insulation properties (thermal conductivity as low as 38.6 mW/mK), thermal stability (no deformation at 140 °C), and mechanical strength. After a basic silane modification, it also shows favorable water resistance (with a contact angle of 128°). Moreover, the foam material demonstrates remarkable degradation performance, with a degradation rate exceeding 93.8 % after 90 days of burial in soil. Therefore, this novel method offers a sustainable solution for eco-friendly foam production across various application domains.

Australian wheat and hardwood fibers for advanced packaging materials

Abstract Alternative crop fibers have shown great potential for paper applications, especially packaging. We demonstrate Australian wheat straw processing using a Regmed MD-3000 disc refiner to produce mechanical pulp fibers and assessment by making 60, 120 and 300 g/m2 handsheets. Wheat fibers and spotted gum fibers were then enzymatically sized (hydrophobized) by esterification to reduce the surface spread of water by 51 % and 36 %, respectively. Coffee pods (300 g/m2 equivalent) were manufactured using a thermoformer to demonstrate the versatility of mechanical wheat straw pulp fibers as a sustainable resource for food packaging application.

Simulation study on heavy metals, phthalate esters, and organic halogens: Content and distribution characteristics during waste paper recycling.

Imported waste paper and recycled pulp may contain pollutants, posing potential environmental risks to the ecosystem of China. This study examined the presence and distribution patterns of heavy metals, phthalate esters (PAEs), and adsorbable organic halogens (AOX) in recycled pulp and production wastewater after various recycling processes of three typical restricted types of imported waste paper. The results indicated that the concentration ranges of heavy metals, PAEs, and AOX in the three types of imported recycled waste paper were 21.61-40.38mg/kg, 15.35-27.88mg/kg, and 19.21-57.72mg/kg, respectively. The comparative analysis with the initial waste paper demonstrated a reduction in heavy metal content in the recycled pulp by 17.80-49.75%, PAEs by 65.42-90.55%, and AOX by 32.80-42.34%. The average concentrations of these pollutants in wastewater were 0.85-1.66mg/L, 27.28-59.86mg/L, and 1.15-3.34mg/L, respectively. Chromium and lead were identified as the primary heavy metals present in the waste paper. Following pulping, No. 1 and No. 2 met the arsenic and lead levels specified in the "Reuse Fiber Pulp" standard (GB/T24320-2021), whereas No. 3 met these criteria after de-inking only. The main PAEs detected in the waste paper were dibutyl phthalate and di(2-ethylhexyl) phthalate, most of which were removed during the pulping stage. Significantly higher levels of AOX were observed in No. 2 and No. 3 than in No. 1, with a minimal impact on AOX removal from the pulp during the recycling process.

Extraction of high-quality moso bamboo fibers by enzyme/alkali synergistic mechanism

As an emerging non-wood resource, moso bamboo has attracted extensive attention because of its short growth cycle and high holocellulose content. However, the internal structure of moso bamboo is more compact than that of wood, leading to higher chemical consumption during the pulping process, which greatly reduces the quality of the extracted fibers. Herein, an innovative pulping system including enzymes and alkali is proposed to achieve higher-quality extraction of moso bamboo fibers. Benefiting from the synergistic effects of high-temperature and alkali-resistant cellulase, xylanase, and laccase, supplemented with alkaline pulping, adequate retention and softening of moso bamboo fibers were ultimately achieved. The sample treated with an enzyme/alkali system resulted in a relative increase in fiber length of 7.19 % and a 31.26 % increase in beating efficiency over alkaline pulping. In addition, the tensile index and tearing index of the paper treated with the enzyme/alkali system reached 50.17 N·m·g−1 and 9.12 mN·m2·g−1, which were 22.52 % and 20.53 % higher than those of the alkaline pulping, respectively. This work provides new insights into the production of high-performance moso bamboo fibers and paper with low energy and alkali consumption.

Synergistic deinking effect of neutral sodium sulfite with fungal hemicellulase enzyme for improved recycling of waste papers

The study examined the beneficial effects of the synergistic deinking and delignification process on the quality of recycled pulp. By utilizing a mixture of neutral sodium sulfite, sodium carbonate, and fungal hemicellulase enzyme, the research demonstrated that the paper achieved enhancements in brightness, whiteness, tensile and burst indices, while also exhibiting reduced yellowness and ERIC in comparison to paper derived from chemically deinked pulp. The high-resolution ESCA analysis demonstrated a reduction in lignin surface coverage, and enhancement in the O/C atomic ratios. FTIR spectra indicated notable alterations in the structure of fibers and the functional groups of deinked pulp fibers. XRD spectra confirmed a higher cellulose crystallinity index and FESEM micrographs illustrated a rougher surface with the emergence of new fibrils. Additionally, UV analysis of the pulp effluents indicated significant lignin absorbance, while post-bleaching with H2O2 further enhanced the reactivity of the pulp and the overall quality of the paper.

Effect of Moisture Contents of Raw Materials on the Dimensional Properties of Thermomechanical Pulp Fibers

Effect of Moisture Contents of Raw Materials on the Dimensional Properties of Thermomechanical Pulp Fibers

Phytochemicals, antioxidant activity and nutritional profile of pulp, peel and peel fiber of mango (<i>Mangifera indica</i> l.) cultivar Ataulfo

Introduction: Mango fruit and its by-products represent a very diverse and abundant source of sugars and components with anti-inflammatory and antioxidant properties, such as dietary fiber, vitamins, and polyphenols. Consuming mango pulp might reduce health disorders caused by inflammatory and oxidative processes such as obesity related diseases. Mango and its by-products contain compounds that can either promote or neutralize inflammatory and oxidative environments; variations in their composition may directly influence the degree of bioactivity. This work aimed to analyze the nutritional and nutraceutical profiles presented in the three different mango by-products to know their possible nutraceutical potential. Objective: This work aimed to analyze the nutritional and nutraceutical profiles presented in the three different mango by-products to know their possible nutraceutical potential. Methods: Ripe Ataulfo mango products (pulp, peel, and peel fiber) were evaluated for nutritional composition by AOAC methods. β-carotene and ascorbic acid were analyzed by UV-Vis liquid chromatography (LC), while mangiferin, phenolics and flavonoids by LC coupled to mass spectrometer detector. The antioxidant capacity was correlated to each of the bioactive compounds. Results: Ripe Ataulfo mango products (pulp, peel, and peel fiber) were evaluated for nutritional, antioxidant, and phytochemical characteristics. All the by-products demonstrated significant differences (P ≤ 0.05) in nutritional and chemical composition. Mango peel had the highest β-carotene, vitamin C, and mangiferin values. Mango pulp had the highest values for free sugars (73 g 100 g-1), but low phytochemicals values, contrasting the peel fiber with 81% of total dietary fiber but minimum values of free sugars and β-carotene and no vitamin C. The highest antioxidant capacity was presented for mango peel. Results obtained from this study indicate that the mango Ataulfo pulp and by-products are divergent and represent a good source of bioactive compounds. Conclusions: Mango peel composition is a natural combination of high concentrations of mangiferin, flavonoids, phenolic acids, vitamin C, provitamin A, and dietary fiber, all involved with inflammation and cell oxidative stress-related disease control and prevention. However, mango peel exhibited the most significant nutraceutical potential due to its high antioxidant capacity. Keywords: Mangifera indica L.; Mango Ataulfo; Mangiferin; Flavonoids; Phytochemicals; Bioactive Compounds

Production of Long-Fiber Pulp from Enset Plant Residues by Soda Pulping.

This paper evaluates the modification of fiber morphology and the strength property development of paper from Enset fiber as a function of soda pulping conditions and refining energy. Soda pulping was conducted at pulping temperatures between 160 and 180 °C. The NaOH charge was 16, 20, and 24% based on the initial raw material. The beating of pulp was conducted using a Jokro mill. The refining of pulp was conducted in a laboratory refiner at different refining intensities. The mild Jokro mill beating was not effective on Enset fiber pulp. On the other hand, the laboratory refiner effectively refined the pulp. The fiber morphology was altered in the way of improving the paper formation and strength. The beating degree of the pulp was increased to about 49 °SR. The tensile index was enhanced to around 80 Nm/g using a refining energy input of 250 kwh/t. From the results, it can be concluded that Enset fiber pulp is suitable for packaging papers due to its high strength level. On the other hand, Enset fiber can be a potential raw material for specialty papers like filter paper and tea bags because of its high porosity.

Pulp fibre foams: Morphology and mechanical performance

Cellulose (pulp) fibre foams serve as bio-based alternative to fossil-based cellular lightweight materials. The mechanical properties of cellulose fibre foams are inferior compared with traditional polymer foams and available information is often limited to compression properties. We present a comprehensive analysis of cellulose fibre foams with densities ranging from 60 to 130 kg/m3, examining their compression, tensile, flexural, and shear properties. Key findings include a high mean zenithal fibre angle which decreases with increasing density, as well as a high strain rate amplification (SRA) in compressive strength, which also decreases with increasing density. With respect to formulation, the addition of carboxymethyl cellulose (CMC) enhanced fibre dispersion, bubble homogeneity of the wet foam, and dimensional stability of the end-product.These results provide a foundation for numerical models and advance the understanding of cellulose pulp fibre foams, highlighting their potential for certain applications.

A deep eutectic solvent with a lignin stabilization and functionalization for lignocellulosic biomass pretreatment

This study synthesized a functional deep eutectic solvent (DES) using betaine and glyoxylic acid (GA) for lignocellulosic biomass pretreatment. The Betaine/GA DES pretreatment resulted a high delignification efficiency of 81.89% and xylan removal of 83.25% while preserving most of cellulose. During pretreatment, lignin was stabilized by GA, preventing its condensation and introducing carboxyl groups onto its molecular backbone. The GA stabilized lignin (GASL), with a high β-O-4 linkage content of 62.92%, was depolymerized for phenolic monomer production with a bio-oil yield of 55.40%. Additionally, the functional lignin was used as a surfactant for GASL-based O/W emulsion (GA-O/W emulsion) preparation. With 0.5% of lignin addition and an optimal O/W ratio of 6:4, the resulting GA-O/W emulsion exhibited a high cream index value of 100% and excellent storage stability without any phase transition or emulsion aggregation. When using the lignin to prepare curcumin-encapsulated microcapsules, a cumulative curcumin remaining of 74.19% under UV radiation and an extraordinary encapsulation efficiency of 62.86% were achieved. Furthermore, this DES pretreatment promoted enzymatic saccharification of the pretreated cellulose substrate, resulting in a glucose yield of 91.49%. After adding 15 wt% of the fibers in soft wood pulp for papermaking, the tear index, ring crush strength index, and tensile index of the produced paper-sheets reached 112.04%, 98.58%, and 83.55% of those of the pure softwood pulp papers, respectively.

Cellulose fiber drainage improvement via citric acid crosslinking

Wheat straw, as a non-wood fiber waste, is available worldwide and can be used in cellulosic matric production, promoting the application of sustainable materials. However, poor fiber properties and water drainage are the primary obstacles to its utilization. In this study, wheat straw pulp fibers were chemically crosslinked by citric acid (CA) in an environmentally friendly process. X-ray photoelectron spectroscopy and Fourier transform infrared spectra confirmed that the chemical treatment introduced carboxylic groups to cellulose fibers. Meanwhile, X-ray diffraction patterns showed that the crystallinity of cellulose was reduced. The average fiber length and water retention value of the pulp decreased with increasing CA dosage under the conditions of 3 mL/g CA4 (4 wt% CA), and the drainage performance of the cellulose pulp improved by 21 %. Also, the crosslinking of fibers contributed to the mechanical properties of the cellulosic matrix, increasing the dry and wet strength by 21 % and 282 %, respectively. These results demonstrated that citric acid could be a sustainable method for improving the properties of wheat straw fibers, thereby promoting its application in fabricating sustainable materials.

Characterization, modeling and prediction of foam-formed softwood fiber sound absorption

The transition towards building materials with low or negative carbon-dioxide footprint is a pressing topic in nowadays society. Materials for thermal and acoustic insulation are among those attracting a growing number of research publications. Commonly used materials in the building sector are mostly mineral wools which demand huge amounts of energy during production by melting sand or stone. Cellulose-based materials are a promising substitute for the current market leaders. These materials are able to reach negative carbon footprints due to low embodied energy and their ability to store carbon dioxide in buildings for decades. Predicting the sound absorption behavior prior to manufacturing can further improve their usability. This study delves into the prediction and characterization of wood-based pulp fiber foams and their acoustic properties. By comparing analytical models, semi-phenomenological models and experimental measurements the prediction of sound absorption based on fiber diameter and bulk density is evaluated. The findings reveal that refining a recent analytical model for natural fibers through parameter fitting to non-acoustic parameters yields improved accuracy in predicting sound absorption curves. While the accuracy declines towards higher densities, this work lays the groundwork to create environmentally sustainable sound absorbers with carefully tailored sound absorption properties.

Extraction of flavonoid dyes from vine tea (Ampelopsis grossedentata) waste and application in bleached pulp dyeing

AbstractNatural dyes are receiving more attention due to wide and renewable resources and their functionalities. This study delved into the optimal conditions for extracting Ampelopsis grossedentata flavonoid dyes (AGFDs) from vine tea waste, resulting in a dye sample with a total flavonoid extraction percentage of 27.4 %. Ultraviolet (UV), Fourier‐transform infrared (FTIR) and liquid chromatography–mass spectrometry (LC–MS) analysis revealed the presence of 18 flavonoids in AGFD. Additionally, various factors, including pH, light exposure, temperature, metal ions, and redox agents were found to impact the stability of AGFD. Moreover, the dyeing performance of AGFD for the bleached chemical pulp was investigated. Under optimal conditions, the AGFD‐dyed pulp displayed a vibrant yellow hue and excellent colour fastness when using aluminum potassium sulphate dodecahydrate (KAl(SO4)2·12H2O) as a mordant with a dyeing uptake level up to 88 %. FTIR and scanning electron microscopy (SEM) analysis demonstrated that AGFD chemically bound to the pulp fibre. Remarkably, the hand sheet made from the AGFD‐dyed pulp exhibited thermal stability, physical strength properties and antibacterial activity against Escherichia coli and Staphylococcus aureus. Furthermore, the peroxide value of cheese packaged with the AGFD‐dyed pulp hand sheet was only 43 % of that of the undyed one, indicating its good antioxidant properties. This study highlights the promising potential of AGFD in the production of functional coloured paper.

Smart paper-based materials incorporating nitrogen and boron co-doped MXene quantum dots for rapid adsorption and sensitive detection of Cr2O72−

Dichromate ion (Cr2O72−) is a highly toxic chromium-containing compound that poses significant hazards to the digestive, respiratory systems, skin, and mucous membranes. Currently, the detection and adsorption of Cr2O72− face significant challenges, including the time-consuming and low sensitivity nature of traditional analytical methods. The limited efficiency and capacity of existing adsorbents hinder their practical application in real-time water quality monitoring and environmental remediation. Herein, using polyethyleneimine-functionalized (PEI) pulp fiber paper as the substrate, we developed smart paper-based materials (designated as NB-MQDs@PP) incorporated with nitrogen and boron co-doped MXene quantum dots (NB-MQDs) for rapid adsorption and sensitive detection of Cr2O72−. Compared to undoped MQDs, NB-MQDs exhibited longer excitation wavelength and enhanced oxidation stability. As anticipated, NB-MQDs achieved rapid (response time of 10 s) and sensitive (detection limit of 1.2 μM) recognition of Cr2O72− within a wide pH range with a quenching efficiency of 99.9%. Simultaneously, two on-site detection methods, immersion and cyclic filtration, were constructed based on NB-MQDs@PP. The detection limit of the immersion method was 17.0 nM, while the cyclic filtration method had a detection limit as low as 3.8 nM, surpassing the majority of those reported literatures. Remarkably, NB-MQDs@PP exhibited outstanding enrichment capacity towards Cr2O72−, with an adsorption capacity of up to 162.4 mg/g. This work provides a novel strategy for creating unique paper-based materials with excellent capture and monitoring dual-function, which can be customized according to the requirements of various application scenarios.

Nanocellulose prepared with γ-valerolactone pretreatment and its enhancement in colored paper

New techniques are always demanded to pursuit green and economical ways for nanocellulose preparation. We herein proposed to use γ-valerolactone (GVL) to facilitate the nanocellulose preparation from bleached bamboo pulp fibers as a green and sustainable pretreatment. The GVL pretreatment caused the bamboo fibers to destruct, resulting in an obviously increased fine fiber content, which was systematically studied to disclose the influence of different factors on the fiber changes. The optimum GVL pretreatment conditions were determined as reaction time of 4 h, reaction temperature of 140 °C and the ratio of GVL to water of 4:1. Notably, the GVL pretreatment caused negligible changes in the functional groups on cellulose, as well as its crystalline structure. The resultant nanocellulose (i.e. G-CNF) had a width of ca. 47 nm and it showed good adsorption capacity towards RR195 dye since an impressive dye uptake rate of 46.81 % was attained. The incorporation of G-CNF significantly improved the coloring performance and the ∆E (color difference) value reached up to 33.73. Improvements in the mechanical properties of RR195 dyed paper were also observed with the incorporation of G-CNF. This work sheds light on the nanocellulose preparation with GVL pretreatment and demonstrates a feasible way to apply the resultant nanocellulose in the colored paper manufacture.

Utilizing Flax Straw for Sustainable Paper Production: Delignification Methods, Structural Analysis, and Fiber Size Distribution Effects

This research explores the potential of agricultural waste, specifically flax straw, as a sustainable raw material for eco-friendly packaging materials. This study investigates a three-stage delignification process involving nitric acid, alkaline treatment, and organosolvent solutions. This method effectively removes lignin from the straw, resulting in high-quality technical pulp with 67.7% α-cellulose and a significantly reduced ash content (8.5%). X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were employed to characterize the treated flax straw. XRD analysis revealed changes in the cellulose structure, while TGA indicated enhanced thermal stability compared to untreated straw. Microscopic analysis of the pulp fibers shows a parallel and aligned arrangement, suggesting a high fiber content and a strong paper lattice. The particle size distribution of the ground pulp, influenced by fiber size, has implications for the packing density and mechanical properties of the final product. This study demonstrates the potential of agricultural waste as a sustainable source for packaging materials, contributing to the circular economy and waste reduction.

Effect of fibre-quality parameters on pulp properties by using multiple linear regression and artificial neural network

Paper strength is developed through pulp refining. This paper investigates a correlation of pulp fibre properties changes by pulp refining with the development of papermaking properties by multiple linear regression (MLR) analysis and artificial neural network (ANN). A total of 21 observations were made on the samples. The available dataset was divided into two groups: 81% of experimental results were selected as training data and 19% for model verification. A satisfactory level of the correlation between simulation data and experimental data was obtained. The linear regression analysis could be used for predicting tensile index (Adj. R2 = .85), tear index (Adj. R2 = .97) and burst index (Adj. R2 = .91) based on the fibre characteristics such as fine content (%), fibre length (mm), fibre width (μm), degree of external fibrillation (%), curl index, kink index and coarseness (mg/m). However, the tensile index, tear index and burst index could be estimated by ANN more efficiently ( R2 > .95).

Total mercury and methylmercury in lake water in years before and after removal of mercury-polluted pulp fiber sediment

There is an elevated presence of mercury (Hg) in the biosphere because of anthropogenic activities. The resulting damage to ecosystems and human health increases dramatically when microorganisms produce highly toxic methylmercury (MeHg). Total Hg (THg), MeHg and ancillary water chemistry were measured in two connected lakes, separated by a short stream stretch, before (1996, 1998 and 2003) and after (2007, 2009 and 2010) the removal of Hg-polluted pulp fiber sediment. Over the study period, there was a decrease in sulfate in the surface water of both lakes, presumably because of declining atmospheric sulfate deposition. Together, the reductions in OM, sulfate, and Hg, resulted in decreased MeHg concentrations as well as decreased MeHg:THg ratios in the bottom water overlying the sediment. There was also a reduction in zooplankton MeHg and fish total Hg in both lakes. Multiple regressions, using the bottom water data before and after remediation from both lakes, indicated that both the yearly maximum MeHg concentration [MeHgmax] and MeHgmax:THg correlated positively with the simultaneously measured sulfate deficit (a proxy for microbial sulfate reduction) and inorganic Hg concentration (IHg = THg – MeHg). This may suggest that the removal of Hg and the decreased sulfate reduction not only led to a decrease in available Hg substrate for methylation but also disfavored the Hg methylation process. As opposed to sulfate deficit, other measurements reflecting heterotrophic microbial activity such as inorganic carbon (IC), ammonium (NH4+), and iron (Fe) did not show significant correlations with MeHg or MeHg:THg when the data from both lakes were combined.

A covariant formulation for finite strain modelling of orthotropic elasticity and orthotropic plasticity with plasticity-induced evolution of orthotropy: Application to natural fibres

We introduce a rate-independent model for orthotropic elastic and orthotropic plastic material behaviour in a hyper-elasto-plastic framework at finite strains. The model is based on the postulate of covariance and does not rely on a multiplicative decomposition of the deformation gradient. Furthermore, a plastic-deformation-induced evolution of orthotropy is considered, similar to the notion of plastic spin. We propose that the orthotropic strain energy function and the orthotropic yield criterion are guided by identical structural tensors that evolve with plasticity. The modelled material behaviour is significant for natural fibres such as flax, hemp, or pulp fibres. Our formulation has three findings. Firstly, the covariant formulation of plasticity provides rate equations for the plastic variables and the structural tensors suitable for reproducing stress–strain diagrams of natural fibres. Secondly, the introduction of plastic-deformation-induced evolution of orthotropy in the proposed covariant setting results in a non-associative plasticity algorithm. Thirdly, the covariant setting allows the incorporation of suitable constitutive equations for the structural tensors to evolve orthotropy. The latter successfully models the stiffness increase in stress–strain diagrams of cyclic tensile tests of natural fibres.