Chemical Pulp Research Articles

Cleaner bio-pulping approach for the production of better strength rice straw paper

The aim of this study was to explore the potential of crude xylano-pectinolytic enzymes in bio-pulping of rice straw, in order to reduce environmental pollution. In this study, the effect of integration of bio-pulping strategy before chemical pulping of rice straw has been investigated. The bio-pulping efficiency was found to be maximum at xylanase:pectinase dose of 400:120 IU/g rice straw, temperature 55 °C, treatment time 3 h, Tween 80 (1%), pH 8.5 and pulping consistency 1:10 (g/mL). Bio-pulping enhanced the permeability of pulping chemicals, generated pulp with higher yield, brightness, along with higher residual active alkali content of black liquor in comparison to the pulp obtained after chemical pulping. Bio-pulping also resulted in 10% reduction of alkali dose and improved paper quality, with increase in breaking length (13.9%), burst index (27.0%), double fold (39.3%), gurley porosity (18.75%) and viscosity (8.77%) of unbleached bio-pulp. Bio-pulping also improved the bleachability by removing the D2 step of bleaching and produced pulp with higher physical strength properties, breaking length (15.92%), burst index (20.47%), tear index (3.87%), double fold (36.0%), gurley porosity (25.0%) and viscosity (28.36%). Hence, this environmentally sustainable bio-pulping approach can decrease the chemical load and ultimately pollution, along with enhance the yield and quality of paper. This is the first report demonstrating cleaner pulping of rice straw using crude xylano-pectinolytic enzymes, produced by a bacterial isolate.

In Situ Wood Delignification toward Sustainable Applications

ConspectusAs one of the most abundant and versatile natural materials on Earth, recently wood has attracted tremendous attention from scientists and engineers due to its outstanding advantages, including hierarchically porous microstructure, high mechanical strength, environmental friendliness, renewability, and biodegradability. Wood’s hierarchically porous structure and chemical components (e.g., cellulose, hemicelluloses, and lignin) enable its mechanical, ionic, optical, and thermal properties to be tuned via physical, chemical, and/or thermal modifications. Among these various approaches, the chemical delignification of bulk wood is the most fascinating, in which the majority of lignin and hemicelluloses is removed while leaving the cellulose intact, maintaining wood’s physical integrity and hierarchical structure. This delignified structure is unique, composed of hollow, aligned channels made up of cellulose microfibrils, and particularly attractive given its origin from a sustainable and renewable resource. As a result, delignified wood has attracted increasing attention for applications that go far beyond traditional wood utilization, such as lightweight yet strong structural materials, energy storage and conversion, environmental remediation, flexible electronics, and bioengineering.This Account reviews recent developments in bulk wood delignification strategies toward the achievement of such advanced wood technologies for sustainable applications, with a focus on the research in our group. Similar to chemical pulping and bleaching, wood delignification involves a series of nucleophilic reactions based on alkaline Na2SO3 or Na2S systems (i.e., chemical pulping) or electrophilic, radical, and oxidation reactions based on H2O2, ClO2, or NaClO systems (i.e., chemical bleaching) to deconstruct, fragment, and promote the hydrophilicity of lignin macromolecules, which finally make lignin easier to be removed. We discuss the structure and properties of partially and near-completely delignified wood, with a focus on process-structure–property relationships. The resulting delignified wood materials, with tunable structure and properties, demonstrate various advanced functions, in a wide range of advanced applications, such as building and construction, green energy, and electronics. Finally, the potential challenges and appealing perspectives of in situ wood delignification are discussed. In situ wood delignification, as a powerful modification strategy, has speeded up the development of advanced wood technologies and wood-based functional materials and products.

Energy consumption, physical properties and reinforcing ability of microfibrillated cellulose with high lignin content made from non-delignified spruce and pine sawdust

The production of MFC and CNF has recently been focused on fiber raw materials which, still contain residual lignin instead of bleached chemical pulp fibers. The target of this study was to assess the energy consumption and microfibrillation rate for high lignin containing microfibrillated cellulose (LMFC) produced from non-delignified pine and spruce sawdust directly or after lignin-preserving sulfonation, and evaluate their grade by measuring strength properties of self-standing films made from the LMFCs and by determining their ability to reinforce fluting board. MFC from bleached softwood was used as a reference.Microfibrillation rate at 80 °C was faster for spruce sawdust than for pine sawdust, i.e., bonding ability (measured as tensile strength of self-standing films) developed faster in spruce LMFC than in pine LMFC. By mild pre-sulfonation of sawdust, corresponding to the sulfonation degree of 0.5−0.6 %, the rate increased further with both softwood species. In similar grinding conditions and equal grinding time, pre-sulfonation did not affect much energy consumption but at a given specific energy consumption the grade of LMFC was better. Due to the high lignin content, mechanical properties of LMFCs could not been developed at as high level than MFC. However, the tensile strength of 100 MPa was possible to achieve for LMFC films using either the equivalent (spruce and sulfonated pine) or even clearly lower amount (sulfonated spruce) of grinding energy than in microfibrillation of bleached Kraft pulp to the same strength.By comparing the pre-sulfonation of sawdust and the post-sulfonation of LMFC, it was concluded that the main sulfonation effect in grinding was lignin softening, which enhanced cell wall disintegration in microfibrillation. The increased bonding ability of sulfonated lignin and the dissolution of extractives were seen to be secondary effects but not without significance. Pre-sulfonation also improved redispersibility, i.e., the recovery of the mechanical properties of dried LMFCs.The reinforcing potential was evaluated by dosing LMFCs and MFC without a retention aid into the handsheets made from fluting pulp. The tensile strength of fluting increased almost linearly with an increasing dosage and increasing microfibrillation time. Although the grade of LMFCs, in terms of viscosity and mechanical properties of LMFC films, was lower than that of MFC from bleached softwood, their ability to reinforce fluting board was shown to be equal, indicating lignin present did not interfere the formation of hydrogen bonds. With a 4 % dosage (equaling to the amount of 2–2.5 % within the handsheets) of each LMFC microfibrillated for 120 min, the tensile strength improved by 20 %. Among the tested raw materials, LMFC from spruce sawdust without pre-sulfonation has the greatest potential as a cost-effective reinforcing agent for the paper and board industry. For sulfonated LMFCs should be found applications where their better bonding ability could be better utilized.

Pengaruh keputusan investasi, struktur modal, profitabilitas, dan kebijakan dividen terhadap nilai perusahaan

The existence of research aims to find out how the company's value occurred in the basic industry and chemical subsector pulp & paper in 2014-2018. In increasing the value of the company, a manager is very influential on decisions taken including investment decisions, dividend policies and funding decisions, every decision taken affects financial decisions. Some factors that affect the value of the company are capital structure, dividend policy, company growth, liquidity, company size and investment decisions. Type of research is quantitative using financial data listed on financial statements listed on the IDX (Indonesia Stock Exchange). Investment decisions are the allocation of capital into investment proposals should be evaluated and linked to the risks and results expected to obtain a high level of return with a certain level of risk. Dividend policy is a decision on whether the profit earned will be divided as dividends or will be withheld as an upcoming investment. The Company may be distributed to shareholders as dividends or withheld in the form of retained earnings to finance the company's investments. The capital structure is the balance of the amount of short-term debt that is permanent, long-term debt, preferred shares and common shares, capital structure decisions. Profitability is revenue minus expenses and losses during the reporting period. Analysis of profitability is critical for creditors and equity investors.

Potential of Using Sugarcane Leaves to Produce Pulp for Paper Making

The search for alternative fiber sources among which non-wood materials have found wide application in pulp and paper production. Sugarcane leaves can be among non-wood sources for papermaking. Tanzania has a lot of sugarcane leaves, which are burned during harvesting period in sugar industries. Therefore, this study aimed at investigating the Potential of using sugarcane leaves to produce pulp for papermaking. This will lead to reduced wood consumption as well as minimization of global warming impact resulting from CO2 emissions as a result of burning of sugarcane fields before harvesting. Pulping of sugarcane leaves was achieved through chemical pulping method (Soda pulping) with two different effective alkali charges (EA-12% and EA-18%) and the pulp obtained were tested for their Kappa number (33.9, 20.9), Pulp yield (35.8%, 27.2%), and Freeness (520CSF and 490CSF). The resulting pulp was used for hand sheet making and the papers obtained were tested for their mechanical properties; Grammage (58.5, 59.4) g/m2, Tensile index (30.5, 41.1) Nm/g, Tear index (9.4, 9.5) Nm2/g, burst index (3.3, 4.7) k.pa.m2/g and Elongation at break (2.57, 2.75) %, for papers made from sugarcane leaves pulp with two different treatments respectively. The overall results showed that Tanzanian sugarcane leaves has a promising potential as alternatives fibers for pulp and paper making industry.

Improved chemical pulping and saccharification of a natural mulberry mutant deficient in cinnamyl alcohol dehydrogenase

Abstract Lignin content and its molecular structure influence various wood characteristics. In this study, the anatomical and physicochemical properties of wood derived from a naturally occurring mulberry mutant deficient in cinnamyl alcohol dehydrogenase (CAD), a key enzyme in lignin biosynthesis, were analyzed using conventional staining assays on stem sections, length and width measurements of xylem fiber cells, wood pulping and saccharification assays, and sugar compositional analysis of extractive-free wood powder. The present data indicate that the mutation in the CAD gene leads to improved wood delignification efficiency, increased pulp yield under alkaline pulping conditions, and enhanced saccharification efficiency following alkaline pretreatment. This study opens up new avenues for the multipurpose use of the mulberry CAD-deficient mutant as a raw material for biorefinery processes, in addition to its traditional use as a favored feed for silkworms.

Use of fines-enriched chemical pulp to increase CTMP strength

In this study, fines-enriched pulp (FE-pulp)—the fine fraction of highly-refined kraft pulp—was benchmarked against highly-refined kraft pulp (HRK-pulp) as a strength agent in eucalyptus chemithermomechanical pulp (CTMP). Both the FE-pulp and the HRK-pulp were produced from unbleached softwood kraft pulp, and equal amounts of those strength agents were added to the original CTMP, as well as to washed CTMP, where most of the fines had been removed. The effects of the added strength agents were evaluated with laboratory handsheets. The FE-pulp proved to be twice as effective as HRK-pulp. Both HRK-pulp and FE-pulp increased the strength of the CTMP handsheets. The bulk of the handsheets decreased, however, as well as the drainability. The addition of 5% FE-pulp resulted in the same strength increase as an addition of 10% HRK-pulp, as well as the same decrease in bulk and CSF. For the handsheets of washed CTMP, the strengths were not measurable; the CTMP lost the sheet strength when the CTMP-fines content was reduced through washing. The reduced strength properties were compensated for by the addition of chemical pulp fines that proved to be an efficient strength agent. The addition of 5% FE-pulp restored the strength values, and at a higher bulk and higher drainability.

CHARACTERISTICS OF PULP OBTAINED FROM MISCANTHUS x GIGANTEUS BIOMASS PRODUCED IN LEAD-CONTAMINATED SOIL

"The main goal of the study was to investigate processing of Miscanthus x giganteus biomass produced in soil contaminated with lead and other trace elements (TEs) into pulp using chemical pulping. The phytoremediation parameters of the plant were measured during two growing seasons, which confirmed that the process can be defined as phytostabilization; the contaminants were mainly concentrated in the roots and practically did not translocate to the stalks and leaves, which permitted the use of the aboveground biomass to process into pulp using the organosolvent cooking. The chemical composition, morphological structure, and microscopic characteristics of various crops’ stalks were investigated and compared with the same parameters received for wood and other non-wood plant materials: rape, flax, hemp, and wheat straw. Indicators of pulp were studied depending on the duration of the organosolvent cooking. After 90 minutes of the cooking process, the peroxide pulp from M. x giganteus had a breaking length of 8300 m, tear resistance of 310 mN, and burst resistance of 220 kPa, testifying the high values of the indicators. Further research should investigate the properties of pulp produced from M. x giganteus biomass grown in soils contaminated with various TEs, as well as the possible translocation of elements to pulp."

Evaluation of the Energy Efficiency Improvement Potential through Back-End Heat Recovery in the Kraft Recovery Boiler

Sustainability and energy efficiency have become important factors for many industrial processes, including chemical pulping. Recently complex back-end heat recovery solutions have been applied to biomass-fired boilers, lowering stack temperatures and recovering some of the latent heat of the moisture by condensation. Modern kraft recovery boiler flue gas offers still unutilized heat recovery possibilities. Scrubbers have been used, but the focus has been on gas cleaning; heat recovery implementations remain simple. The goal of this study is to evaluate the potential to increase the power generation and efficiency of chemical pulping by improved back-end heat recovery from the recovery boiler. Different configurations of heat recovery schemes and different heat sink options are considered, including heat pumps. IPSEpro simulation software is used to model the boiler and steam cycle of a modern Nordic pulp mill. When heat pumps are used to upgrade some of the recovered low-grade heat, up to +23 MW gross and +16.7 MW net power generation increase was observed when the whole pulp mill in addition to the boiler and steam cycle is considered as heat consumer. Combustion air humidification proved to yield a benefit only when assuming the largest heat sink scenario for the pulp mill.

Effect of Pretreatments on the Enzymatic Hydrolysis of High-Yield Bamboo Chemo-Mechanical Pulp by Changing the Surface Lignin Content.

Hydrogen peroxide chemo-mechanical pulp (APMP), sulfonated chemo-mechanical pulp (SCMP), and chemical thermomechanical pulp (CTMP) were used as raw materials to explore the effects of hydrogen peroxide (HP), Fenton pretreatment (FP), and ethanol pretreatment (EP) on the enzymatic hydrolysis of high-yield bamboo mechanical pulp (HBMP). The surface lignin distribution and contents of different HBMPs were determined using confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). The correlation between the surface lignin and the enzymatic hydrolysis of HBMP was also investigated. The residue of enzymatic hydrolysis was used to adsorb methylene blue (MB). The results showed that the cracks and fine fibers on the surface of APMP, SCMP, and CTMP increased after FP, when compared to HP and EP. The total removal content of hemicellulose and lignin in SCMP after FP was higher than with HP and EP. Compared to SCMP, the crystallinity increased by 15.4%, and the surface lignin content of Fenton-pretreated SCMP decreased by 11.7%. The enzymatic hydrolysis efficiency of HBMP after FP was higher than with HP and EP. The highest enzymatic hydrolysis of Fenton-pretreated SCMP was 49.5%, which was higher than the enzymatic hydrolysis of Fenton-pretreated APMP and CTMP. The removal rate of MB reached 94.7% after the adsorption of the enzymatic hydrolysis residue of SCMP. This work provides an effective approach for a high value-added utilization of high-yield bamboo pulp.

Pulp and Paper Industry: Decarbonisation Technology Assessment to Reach CO2 Neutral Emissions—An Austrian Case Study

The pulp and paper (P&P) sector is a dynamic manufacturing industry and plays an essential role in the Austrian economy. However, the sector, which consumes about 20 TWh of final energy, is responsible for 7% of Austria’s industrial CO2 emissions. This study, intending to assess the potential for improving energy efficiency and reducing emissions in the Austrian context in the P&P sector, uses a bottom-up approach model. The model is applied to analyze the energy consumption (heat and electricity) and CO2 emissions in the main processes, related to the P&P production from virgin or recycled fibers. Afterward, technological options to reduce energy consumption and fossil CO2 emissions for P&P production are investigated, and various low-carbon technologies are applied to the model. For each of the selected technologies, the potential of emission reduction and energy savings up to 2050 is estimated. Finally, a series of low-carbon technology-based scenarios are developed and evaluated. These scenarios’ content is based on the improvement potential associated with the various processes of different paper grades. The results reveal that the investigated technologies applied in the production process (chemical pulping and paper drying) have a minor impact on CO2 emission reduction (maximum 10% due to applying an impulse dryer). In contrast, steam supply electrification, by replacing fossil fuel boilers with direct heat supply (such as commercial electric boilers or heat pumps), enables reducing emissions by up to 75%. This means that the goal of 100% CO2 emission reduction by 2050 cannot be reached with one method alone. Consequently, a combination of technologies, particularly with the electrification of the steam supply, along with the use of carbon-free electricity generated by renewable energy, appears to be essential.

Ceibapentandra (L.) Gaertn (Kapok) Seed Fibre as a Recycled Paper Reinforcement Pulp

The kapok (Ceibapentandra (L.) Gaertn) seed fibre is unicellular with length up to 35 mm, however, it is covered by a hydrophobic waxy layer that limits its application in paper production. In this study, the effect of various pulping methods namely mechanical, chemi-mechanical, semichemical and chemical pulping on kapok fibre properties was investigated. Each kapok pulp was then blended with the secondary fibre recovered from kraftliner board for handsheet making to examine their reinforcing ability on strength properties. The results showed that kapok mechanical pulps (with and without dewaxing (5% (v/v) diluted detergent) and chemimechanical pulp were unable to improve the strength properties of the handsheet. Kapok pulps chemically treated with 18–25% of sodium hydroxide gave a better effect on handsheet strength properties whilst fibre treated with 20% sodium hydroxide showing the highest increment. Although the reinforcing effect of the 4% native cooked starch was slightly higher than that of the 10% kapok pulp blended in recycled paper, the recycling potential of the latter was better as all strength properties retained unchanged after recycling. The findings indicated that kapok chemical pulp is a promising reinforcing fibre source with superior recycling potential.

Green Assessment of Imports and Exports of Wooden Forest Products Based on Forest Processing Industry: A Case Study of China

The research on international trade competitiveness is progressing continuously. Environmental factors have been gradually considered in the competitiveness of international trade. However, the green assessment system of international trade competitiveness is not perfect. Building a model based on the trade economy is complex. This study combines environmental pollution data based on the forest processing industry with trade flows. Environmental trade competitiveness, pollution treatment, and trade scale were selected as the three criterion levels to construct an assessment system. The weight and score of each index were calculated by the overall entropy method. The overall entropy method is more comprehensive than the traditional entropy weight method due to introduce longitudinal comparisons of time and category. This method is a dynamic evaluation model with analysis of three-dimensional sequential data tables. The use of this method enables the assessment model to analyze more comprehensively the green level of a country’s trade in wooden forest products in terms of time and product category. The green level of chemical wood pulp and sawn timber trade in China is at a high level. The pollution treatment and trade scale of chemical wood pulp and sawn timber attained a medium level of matching. The trades in particle board, hardboard, newsprint, carton board, and wrapping paper are at medium levels of green. The trades in medium density fiberboard and plywood have poor levels of green and need to improve their green production capacity. It is suggested that China should increase investment in scientific research, as well as establish policies to restrict and treat pollution in the industry of wooden forest products, while increasing the export volumes of products with high added value. China should attach importance to the pollution resulting from the manufacture of wooden forest products. The state should support policies for these producers reducing production emissions.

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.

Application of In Situ Calcium Carbonate Process for Producing Papermaking Fillers from Lime Mud.

A portion of the lime mud formed during the causticizing process in the recovery process of kraft pulping should be purged from the calcium cycle as waste before it is fed to the lime kiln; this ensures that the quality of the pulp and pulping chemicals is maintained. The discharged greenish-gray lime mud, which is often disposed as an industrial waste, has been transformed herein into a high-quality papermaking filler via the hybrid calcium carbonate (HCC) and post-HCC (pHCC) technology. Initially, the lime mud was heat-treated and then ground to small-size particles. The ground lime mud was preflocculated with calcium oxide by ionic polymers, and carbon dioxide was injected to the flocs to produce lime mud HCC (LHCC). To produce lime mud pHCC (pLHCC), only the ground lime mud was preflocculated first, calcium oxide was added next, and finally, carbon dioxide was injected to the flocs. The resultant products, LHCC and pLHCC, gave brightness as high as that of the ground calcium carbonate (GCC) in paper while a little higher brightness for pLHCC than for LHCC. They also enabled to increase bulk, stiffness, and tensile strength. Application of the LHCC and pLHCC technology to the lime mud could save waste disposal expenses and produce better-quality paper.

Use of Endoglucanase and Accessory Enzymes to Facilitate Mechanical Pulp Nanofibrillation

Although selective enzyme treatments have been used to successfully fibrillate chemical pulps, high lignin-containing mechanical pulps have proven to be more recalcitrant. When a bleached chemi-thermomechanical pulp (BCTMP) was sulfonated prior to enzymatic treatment, relatively good fibrillation was achieved, although some pulp hydrolysis occurred after 6 h hydrolysis when using a commercial cellulase enzyme preparation (Cellic CTec 3). To try to minimize pulp losses, various enzyme cocktails, including endoglucanase (EG), xylanase, mannanase, and lytic polysaccharide monooxygenase (LPMO), were assessed for their ability to enhance fibrillation while minimizing cellulose hydrolysis. It was apparent that the yield as well as the zeta potential of the lignin-containing cellulose nanofibrils increased with enzyme treatment. This was likely due to an increase in surface charge and a decrease in particle size after LPMO and hemicellulase treatments, respectively. When carbohydrate-binding modules (CBMs) were used to quantify fiber changes, it was apparent that sulfonation had increased the accessibility of enzymes, while the combined action of the hemicellulases and LPMO increased EG accessibility to the less-ordered regions of the mechanical pulp, resulting in enhanced fibrillation. This work described, for the first time, the synergistic action of EG and various accessory enzymes enhancing mechanical pulp nanofibrillation.

Synergistic action of EmimAc and aqueous NaOH for selective dissolution of hemicellulose for cellulose purification

Aqueous EmimAc has been proved as a novel solvent for the selective separation of hemicellulose from chemical pulp. In this work, aqueous NaOH (NaOH-a) has been incorporated into the EmimAc solution to improve the hemicellulose separation. The interaction between NaOH-a and EmimAc has been investigated. In contrast to EmimAc/H2O system, EmimAc/NaOH-a shows better separation of hemicellulose from chemical pulp. In this case, introduction of NaOH with concentration 3–5% has negligible effect on crystal structure and DP of cellulose. Moreover, a dilute NaOH (3–5%) introduction can reduce the viscosity of the pulp-EmimAc/NaOH-a system, which is beneficial for the subsequent separation process. In addition, concentrated NaOH-a (7–10%) will lead to a substantial cellulose dissolution and therefore significant viscosity increase. The further study indicates that addition of NaOH to the aqueous EmimAc can weaken the acidity of hydrogen bond (α) and increase the net basicity (β − α), which are beneficial for the hemicellulose separation.

A general Life Cycle Assessment framework for sustainable bleaching: A case study of peracetic acid bleaching of wood pulp

Bleaching is an important industrial operation that has significant environmental impacts. Many new bleaching technologies have been developed; nonetheless, it is challenging to quantify their potential environmental impacts due to the lack of quantitative information and robust analysis methods across different bleaching agents. This study addresses this gap by developing a general Life Cycle Assessment (LCA) framework that integrates LCA with manufacturing process simulations and lab-scale bleaching experiments. The framework was applied to a case study of Peracetic Acid (PAA), a promising bleaching agent, used in the Total Chlorine-Free (TCF) technology for wood pulp production, compared with the traditional Elemental Chlorine-Free (ECF) using chlorine dioxide. Different PAA synthetic pathways (i.e., using acetic acid or triacetin) and bleaching charges were explored using scenario analysis. Results showed that PAA-based TCF achieves a brightness similar to the conventional ECF technology with lower life-cycle impacts in categories such as global warming and eutrophication. From a process perspective, PAA-based TCF reduces the consumption of energy, water, pulping chemicals, completely avoids the use of chlorinated compounds, and provides enhanced process safety. The source of PAA significantly affects the life-cycle environmental impacts of pulp bleaching. Using PAA synthesized from triacetin rather than acetic acid leads to higher environmental impacts; however, such impacts can be mitigated by reducing excessive use of triacetin (direction for future optimization) or using bio-based glycerin in the production of the triacetin feedstock for PAA production. Although this case study focuses on PAA bleaching for wood pulp, the framework has the potential to be used for other/same bleaching agents in different industrial sectors.

A review of the traditional pulping methods and the recent improvements in the pulping processes

The demand for paper and pulp-derived products to fulfill consumer needs is increasing considerably globally. This work provides a critical overview of the various traditional pulping methods and describes the recent improvements in pulping processes. A comparison of different pulping techniques has shown that the mechanical pulping process produces high pulp yields per unit volume of wood of poor quality (low strength, bonding, fiber morphology, etc.) as compared to chemical pulping methods. The use of semi-chemical pulping is reported as an effective way of overcoming the disadvantages of the mechanical pulping process. Recent modifications of the pulping processes that have happened in the last decade have been discussed and shown to be driven by the desire to save energy and reduce chemical requirements while maximizing pulp yields and quality. With the emergence of bio-based nanotechnology, post-pretreatment of Kraft and sulfite pulps for making nanocellulose and lignin-containing nanocellulose with improved fiber characteristics of fiber size, crystallinity, chemical composition, and fiber surface functionality has been discussed. Furthermore, challenges and prospects of the improvements in pulping processes are highlighted.

Extraction and characterization of nanofibrillated cellulose from yacon plant (Smallanthus sonchifolius) stems

This study aimed to evaluate the process of cellulose extraction from yacon stem using combined pulping and bleaching processes to produce nanofibrillated cellulose (NFC). First, a chemical pulping process with NaOH was applied and, subsequently, the pulp obtained was bleached. From the chemical pulp (CP) bleached, NFC was obtained by the mechanical defibrillation in a colloidal grinder. Then, chemical composition, and infrared analysis of the pulps were performed. The pulping process showed a lower amount of extractives and lignin content, as a low yield and an excessively dark pulp. The CP bleached with NaClO2 showed the best results increased whiteness of the pulp. A suspension of NFC with fibers of 5-60 nm in diameter, high crystallinity index, and thermal stability was obtained. The results are promising and demonstrate the technical feasibility of obtaining NFC from yacon stems waste which is ideal to apply to other materials of the industry.