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Regioselective C6 and C2,C3 carboxylated cellulose nanofibrils (CNFs) have been robustly generated from dissolving pulp, a readily available source of unmodified cellulose, via stoichiometrically optimized 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO)-mediated and sequential sodium periodate-sodium chlorite (PC) oxidation coupled with high-speed blending. Both regioselectively optimized carboxylated CNF series possess the widest ranges of comparable charges (0.72-1.48 mmol/g for T-CNFs vs. 0.72-1.10 mmol/g for PC-CNFs), but similar ranges of thickness (1.3-2.4 nm for T-CNF, 1.8-2.7 nm PC-CNF), widths (4.6-6.6 nm T-CNF, 5.5-5.9 nm PC-CNF), and lengths (254-481 nm T-CNF, 247-442 nm PC-CNF). TEMPO-mediated oxidation is milder and one-pot, thus more time and process efficient, whereas the sequential periodate-chlorite oxidation produces C2,C3 dialdehyde intermediates that are amenable to further chemical functionalization or post-reactions. These two well-characterized regioselectively carboxylated CNF series represent coherent cellulose nanomaterial models from a single woody source and have served as references for their safety study toward the development of a safer-by-design substance evaluation tool.

StExCell, a novel sulfur-free and chlorine-free biorefinery concept, based on mild steam explosion followed by mild caustic extraction, oxygen delignification and bleaching, is introduced to produce dissolving pulp for textile application. Steam explosion of Betula pendula at 210 °C for 7 isothermal min (equivalent to a P-factor of ca. 1,250), combined with a total-chlorine-free purification sequence resulted in a fully bleached pulp with only 3.6 % xylan, a slightly wider cellulose molar mass distribution and a higher pulp yield, while consuming only about half of the chemicals, in reference to a prehydrolysis-kraft process. The chemical recovery and valorization of the extracted wood component were not covered by the scope of this work but speculated to be simpler than in a kraft process. [ABSTRACT FROM AUTHOR]

Dissolving-grade pulps serve as the primary material for producing regenerated cellulose fibers, and their utilization is steadily increasing. Despite extensive research efforts, it remains necessary to deepen our understanding of the inherent factors that impact pulp reactivity apart from the well-known degree of polymerization. The Fock reactivity test is commonly used to quantify the reactivity of cellulose pulp by measuring the percentage of cellulose that reacts with carbon disulfide. Dissolving pulps typically require a reactivity of over 90%. Hemicellulose content, intrinsic viscosity, cell wall porosity, crystallinity, and accessible area of four different pulps were characterized and distinct treatments were employed to try to separate the effect of different pulp properties and assess their effect on Fock reactivity. Hemicelluloses removal by xylanase and cold caustic treatments (86% removal) increased the Fock reactivity by 30%, from 55.7% to 71.3%. Assuming the hemicelluloses are fully accessible by the CS2, cellulose reactivity increased from 35.6% to 69.5%,but at the expense of an intrinsic viscosity decrease from 990 cm3/g to 689 cm3/g. This unexpected intrinsic viscosity decrease can be due to the cellulose de-shielding effect provoked by hemicellulose removal and some cellulose degradation during cold caustic extraction. Vibrational impact ball-milling applied on a pulp with 5% hemicellulose content notably boosted Fock reactivity by 56%, from 54% to 84.5%, but two pulp properties, intrinsic viscosity, and crystallinity, decreased concurrently due to the high-energy treatment. This phenomenon complicates identifying a direct correlation between heightened reactivity and a single parameter. To address this, endoglucanase treatment was used to separate intrinsic viscosity from crystallinity, clarifying their contributions to changes in Fock reactivity. Unfortunately, the effect of a given physical or bio/chemical pulp treatment affects more than one pulp property, always including the cellulose degree of polymerization, which has made it difficult to isolate the pulp properties that affect Fock reactivity. Several processes have been tested to obtain pulp with dissolving potential. [ABSTRACT FROM AUTHOR]

This study investigates the influence of hole diameter and hole spacing on the fractionation performance using an industrial scale pressure screen. The objective is to increase the quality of the long fiber fraction during dissolving pulp production by separating cellulosic fines from unbleached softwood sulfite pulp containing 8% (w/w) primary fines (fibrous particles shorter than 0.200 mm fiber length). Different screen basket designs were applied, using the same hole spacing while varying hole diameter, and vice versa. This allowed a comparison of the separate influence of hole diameter and hole spacing on the separation efficiency. Production parameters of screening devices are always a compromise between separation efficiency, runnability/plugging, and throughput. High aperture velocity, high feed consistency and low reject rate were identified as the crucial operating parameters for high cellulosic fines removal efficiency, which turned out to be positive in terms of throughput. Considering the different hole diameters, the industrial trials showed that smaller holes yielded better fractionation results. Whereas reduced hole spacing resulted in a denser fiber network on the screen, reducing the amount of fines and short fibers passing, thereby leading to worse fractionation results. By choosing suitable screening conditions, we found that the weight-weighted fines content was reduced more than 50 percent using a one stage fiber fractionation screen set up under industrial conditions. The lowered fines content in the long fiber fraction is expected to allow a reduced purification effort and a lower chemical demand in the subsequent processes of dissolving pulp production. By reducing the fines fraction, consisting of short fibers, fiber fines, as well as mainly short-chain alkali-soluble carbohydrates (hemicelluloses), improvements in process efficiency and dissolving pulp quality can be achieved. [ABSTRACT FROM AUTHOR]

The problems of obtaining cellulose suitable for regeneration (cellulose for chemical processing) have been described. A variety of pretreatment techniques are used to activate cellulose. Manmade fibers from regenerated cellulose are produced by wet and wet air-gap spinning. The processes of production of viscose cellulose and copper–ammonia cellulose, as well as the Lyocell process, are used that are based on N-methylmorpholine-N-oxide and ionic liquids. [ABSTRACT FROM AUTHOR]

Following the circular bioeconomy concept, this work studies the potential of an industrial wastepaper residue as an alternative raw material for dissolving pulp‐grade production. Prehydrolysis‐kraft cooking (PHK), elemental chlorine‐free (ECF) bleaching, and acid‐washing treatments were applied to achieve that aim. Considering the high lignin and hemicellulose content of the raw material, it was submitted to PHK pulping to enhance its cellulose content by removing those components. This processing resulted in a remarkable increase of 84 % in pulp Fock reactivity (from 45.6 % to 84.1 %). The dissolution extension and time in solvent systems LiCl/DMAc and NMMO/H2O were discussed regarding the pulp physicochemical properties. The dissolving pulp produced under this work showed great potential as raw material for textile applications, particularly highlighting the innovative process developed to improve its solubility. [ABSTRACT FROM AUTHOR]

This preliminary study investigated an environmentally friendly method for fabricating cellulose-rich dissolving pulp from Oil Palm (Elaeis guineensis) Trunk (VBOPT) fibre. This method encompassed an autohydrolysis pretreatment followed by soda pulping procedures. The impact of autohydrolysis pretreatment on the separation of lignocellulosic components was scrutinised to facilitate the production of chemical cellulose. Autohydrolysis was performed on VBOPT fibre for 60 min at temperatures ranging from 140°C to 160°C, maintaining a solid-to-liquid ratio of 1:8. The yield of the prehydrolysed OPT varied between 73.5% and 91.5%. The chemical composition of the prehydrolysed VBOPT fibre comprised 70.6-80.0% holocellulose, 63.7-87.1% α-cellulose, 7.4-10.9% ß-cellulose, 5.5-25.4% γ-cellulose, and 21.5-26.6% lignin. The prehydrolysed OPT was subsequently subjected to alkaline pulping under fixed conditions: a temperature of 160°C, a treatment time of 60 min, a chemical charge of 25%, and a solid-to-liquid ratio of 1:6. The resultant pulp exhibited properties such as a screening yield of 41.5-46.4%, a kappa number of 4.5-9.6, and α, β, and γ cellulose content of 89.4-98.1%, 1.5-5.3%, and 0.4-6.9%, respectively. Based on the chemical composition of the OPT biomass before and after pretreatment, as well as post-alkaline cooking, the autohydrolysis pretreatment was determined to significantly influence the resultant pulp. A more comprehensive understanding of the interdependence of autohydrolysis and pulping processes can be achieved by executing an optimisation study focusing on key parameters of autohydrolysis and pulping, including temperature, treatment duration, and chemical charge. [ABSTRACT FROM AUTHOR]

γ-Valerolactone (GVL) is a promising biomass-based platform compound that can be used for the removal of hemicellulose in pulp. In this study, a paper-grade pulp was treated using GVL to generate dissolving pulp for viscose production. The GVL concentration, treatment temperature, and reaction time had significant effect on the hemicellulose dissolution. The dissolving pulp with a-cellulose content of 92.3% and hemicellulose content of 5.45% was achieved with 60% GVL at 120 °C for 2 h. The Fock reactivity and intrinsic viscosity of the obtained dissolving pulp were 54.6% and 595 mL/g, which is comparable with the commercial product. In addition, GVL spent liquor was also recycled and reused to upgrade paper-grade pulp. By using purified recycled GVL to treat original pulp, the Fock reactivity of pulp was improved, and the cellulose content of asprepared upgraded pulp increased to 92.1%, which was close to the cellulose content of dissolving pulp obtained from fresh GVL solution, while the intrinsic viscosity decreased significantly to 598 mL/g. Therefore, the efficient reuse of GVL not only ensured the high quality of dissolving pulp, but it also saved production costs and reduced environmental pollution. [ABSTRACT FROM AUTHOR]

As the global population grows, the demand for textiles is increasing rapidly. However, this puts immense pressure on manufacturers to produce more fiber. While synthetic fibers can be produced cheaply, they have a negative impact on the environment. On the other hand, fibers from wool, sisal, fique, wood pulp (viscose), and man-made cellulose fibers (MMCFs) from cotton cannot alone meet the growing fiber demand without major stresses on land, water, and existing markets using these materials. With a greater emphasis on transparency and circular economy practices, there is a need to consider natural non-wood alternative sources for MMCFs to supplement other fiber types. However, introducing new feedstocks with different compositions may require different biomass conversion methods. Therefore, based on existing work, this review addresses the technical feasibility of various alternative feedstocks for conversion to textile-grade fibers. First, alternative feedstocks are introduced, and then conventional (dissolving pulp) and emerging (fibrillated cellulose and recycled material) conversion technologies are evaluated to help select the most suitable and promising processes for these emerging alternative sources of cellulose. It is important to note that for alternative feedstocks to be adopted on a meaningful scale, high biomass availability and proximity of conversion facilities are critical factors. In North America, soybean, wheat, rice, sorghum, and sugarcane residues are widely available and most suitable for conventional conversion through various dissolving pulp production methods (pre-hydrolysis kraft, acid sulfite, soda, SO2-ethanol-water, and potassium hydroxide) or by emerging cellulose fibrillation methods. While dissolving pulp conversion is well-established, fibrillated cellulose methods could be beneficial from cost, efficiency, and environmental perspectives. Thus, the authors strongly encourage more work in this growing research area. However, conducting thorough cost and sustainability assessments is important to determine the best feedstock and technology combinations.

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As the global population grows, the demand for textiles is increasing rapidly. However, this puts immense pressure on manufacturers to produce more fiber. While synthetic fibers can be produced cheaply, they have a negative impact on the environment. On the other hand, fibers from wool, sisal, fique, wood pulp (viscose), and man-made cellulose fibers (MMCFs) from cotton cannot alone meet the growing fiber demand without major stresses on land, water, and existing markets using these materials. With a greater emphasis on transparency and circular economy practices, there is a need to consider natural non-wood alternative sources for MMCFs to supplement other fiber types. However, introducing new feedstocks with different compositions may require different biomass conversion methods. Therefore, based on existing work, this review addresses the technical feasibility of various alternative feedstocks for conversion to textile-grade fibers. First, alternative feedstocks are introduced, and then conventional (dissolving pulp) and emerging (fibrillated cellulose and recycled material) conversion technologies are evaluated to help select the most suitable and promising processes for these emerging alternative sources of cellulose. It is important to note that for alternative feedstocks to be adopted on a meaningful scale, high biomass availability and proximity of conversion facilities are critical factors. In North America, soybean, wheat, rice, sorghum, and sugarcane residues are widely available and most suitable for conventional conversion through various dissolving pulp production methods (prehydrolysis kraft, acid sulfite, soda, SO2 -ethanol-water, and potassium hydroxide) or by emerging cellulose fibrillation methods. While dissolving pulp conversion is well-established, fibrillated cellulose methods could be beneficial from cost, efficiency, and environmental perspectives. Thus, the authors strongly encourage more work in this growing research area. However, conducting thorough cost and sustainability assessments is important to determine the best feedstock and technology combinations. [ABSTRACT FROM AUTHOR]

In recent years, there has been a consistent increase in viscose staple fiber (VSF) production, leading to an increased demand for dissolving pulp among producers. The properties of the pulp play a crucial role in influencing the efficiency of viscose operation, necessitating the selection of efficient raw materials. Therefore, this study aimed to evaluate the differences in chemical properties, fiber morphology, and viscose performance of fractionated pulp during alkalizing and aging processes. Alkalizing and aging were carried out under similar conditions for all fractions tested. The pulp samples consisted of reference (REF), long-fiber (LF), medium fiber-long (MFL), medium fiber-short (MFS), and short-fiber fractions (SF). The chemical analysis results showed that SF had the lowest viscosity, alpha-cellulose, and molecular weight. Physical properties of SF also had the lowest cell wall thickness (CWT), cross-section area (CSA), and coarseness, but it had the highest fiber population and water retention value (WRV) compared to LF. These characteristics significantly affected the quality of alkaline cellulose and the degree of polymerization rate during the aging process. SF showed the fastest depolymerization time (145 minutes) to achieve a target viscosity of 240 mL/g compared to others (192–194 minutes). However, aging rate was constant for all the samples examined. Based on the results, MFL was considered the ideal fraction for the viscose process due to its suitable fiber characteristic, leading to good behavior in alkalizing and aging. The samples also had an acceptable initial viscosity (478 mL/g) and a predominant fraction yield (30%), showing enhanced productivity.

Deep eutectic solvent (DES) provides promising alternatives to conventional pulping and cellulose purification with significantly lower energy consumption and impacts on the environment. In this work, choline chloride – lactic acid (ChCl-LA DES) pulping of eucalyptus wood chips combined with several ECF bleaching sequences was investigated to produce high-grade dissolving pulps. Initially, the dependency of DES pulping yield and delignification efficiency on the moisture content (MC) of used wood chips was evaluated. The results exhibited the crucial influence of the MC of wood chips on the delignification efficiency of DES pulping. DES pulping under optimized conditions resulted in an unbleached pulp with kappa number of 42, relatively high screened yield 48.1% and viscosity 796 cm3/g, as well as very low hemicellulose content, typically less than 3.8%. Further purification of the obtained pulp using D-Ep-D and OO-D-Ep-D bleaching sequences produces several dissolving pulps characterized by a high viscosity 695 cm3/g and brightness 89.5% ISO, indicating low degradation of cellulose during DES pulping. DES pulping exhibited considerable potential to remove the hemicelluloses from wood chips and produce high-quality dissolving pulps. This could be attained through shorter pulping operations conducted at a lower temperature and a higher screened yield compared to current dissolving pulp production operations. Deep eutectic solvent is able to delignify eucalyptus wood chips efficiently at moderate temperature. Moisture content of eucalyptus wood chips has crucial influence on pulping. Pulp contains very low hemicellulose. DES pulps are bleached easily using ECF bleaching sequences. DES pulping of eucalyptus wood chips followed by ECF bleaching produces high quality dissolving pulp with low energy and chemical consumption. [ABSTRACT FROM AUTHOR]

The paper discusses experimental techniques for pulping, bleaching, and creating manmade fibers based on Na-sulfite and Mg-bisulfite dissolving pulps utilizing a dry-jet wet spinning procedure with solutions in N-methylmorpholine-N-oxide. After pulping, Mg-bisulfite pulp had a cellulose yield of 46.1% and Na-sulfite pulp of 44.0%. For Na-sulfite and Mg-bisulfite pulps, the Kappa number was 14.1 and 15.6 units, respectively. According to TCF technology, the overall yield of the semi-finished product after bleaching was 33.5% for Na-sulfite pulp and 36.4% for Mg-bisulfite pulp. For Na-sulfite and Mg-bisulfite pulps, the α-cellulose content was 92% and 91%, respectively. Spinning solutions of various concentrations were obtained from the resulting cellulose, and their rheological behavior was determined. The fibers were spun using the dry-jet wet spinning technique from 14% cellulose solutions, and their morphology and structure were examined. The fibers' revealed mechanical properties are superior to viscose fibers and on par with those of commercial Lyocell fiber analogs. [ABSTRACT FROM AUTHOR]

In recent years, there has been a consistent increase in viscose staple fiber (VSF) production, leading to an increased demand for dissolving pulp among producers. The properties of the pulp play a crucial role in influencing the efficiency of viscose operation, necessitating the selection of efficient raw materials. Therefore, this study aimed to evaluate the differences in chemical properties, fiber morphology, and viscose performance of fractionated pulp during alkalizing and aging processes. Alkalizing and aging were carried out under similar conditions for all fractions tested. The pulp samples consisted of reference (REF), long-fiber (LF), medium fiberlong (MFL), medium fiber-short (MFS), and short-fiber fractions (SF). The chemical analysis results showed that SF had the lowest viscosity, alpha-cellulose, and molecular weight. Physical properties of SF also had the lowest cell wall thickness (CWT), cross-section area (CSA), and coarseness, but it had the highest fiber population and water retention value (WRV) compared to LF. These characteristics significantly affected the quality of alkaline cellulose and the degree of polymerization rate during the aging process. SF showed the fastest depolymerization time (145 minutes) to achieve a target viscosity of 240 mL/g compared to others (192-194 minutes). However, aging rate was constant for all the samples examined. Based on the results, MFL was considered the ideal fraction for the viscose process due to its suitable fiber characteristic, leading to good behavior in alkalizing and aging. The samples also had an acceptable initial viscosity (478 mL/g) and a predominant fraction yield (30%), showing enhanced productivity. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract There is increasing attention to the production of cellulose nanocrystals (CNCs) from lignocellulosic biomass by enzymatic hydrolysis with cellulase. In this study, the feasibility of the application of a cellulase system from engineered strain Penicillium oxalicum cEES in the production of CNCs was assessed. Using commercial eucalyptus dissolving pulp (EDP) as substrate, the CNCs were successfully obtained by enzymatic hydrolysis with the cellulase cEES, and the total yields of CNCs reached 15.7% through three-step enzymatic hydrolysis of total 72 h (24 h for each step). The prepared CNCs were characterized and found that their crystallinity and thermal stability were higher than that of EDP. In the later stage of enzymatic hydrolysis, the process efficiency of enzymatic preparation of CNCs greatly decreased because of the high crystallinity of cellulosic substrate, and a simple homogenization treatment can promote the enzymatic hydrolysis, as well as produce fusiform CNCs with more uniform size and more fermentable sugar that could be further converted into fuels and bulk chemicals through fermentation. This study provides a feasible enzymatic preparation process for CNCs with engineered cellulase and commercial cellulosic materials. Graphical Abstract

Converting paper-grade bleached Kraft pulp into dissolving pulp using eco-friendly chemicals on-site at the mill is a challenge for the pulp industry. In this study, two oxidation systems are evaluated: the first one is based on the use of hydrogen peroxide at various levels of alkalinity; the second one investigates the use of sodium periodate followed by hydrogen peroxide to convert aldehydes into carboxyls and enhance their hemicelluloses removal. Our results have shown that when using only peroxide, the removal of hemicelluloses was not sufficient to improve the pulp's dissolving ability. Conversely, the periodate–peroxide system proved to be more efficient. Results regarding the pulp purity, solubility, degradation (pulp viscosity and cellulose molecular mass distribution), brightness, and its potential applications were discussed. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Studies have elucidated that the trends in dissolving pulp markets worldwide are growing consistently and rapidly. In 2018, the global revenue generated from dissolving pulp amounted to $9.3 billion, this being a 6.50% increase from the previous year. Dissolving pulp is a high-purity cellulose product predominantly produced from wood and is used in a wide variety of applications such as pharmaceutical, textile, food, paint, and coating industries. In recent times, the demand for dissolving pulps has shown a buoyant increase leaving a wide gap between supply and demand. A review of literature highlighted that two dominant manufacturing processes for dissolving pulp employed by industries across the world are the prehydrolysis kraft (PHK) and AS processes. Factors identified to significantly affect both processes include raw material characteristics, processing conditions such as temperature, time, and the type and concentration of chemicals used in the various processes (pretreatment, pulping, and posttreatment). Several pre-pulping treatments and post-pulping treatments have been identified as key processes that assist in achieving the desired cellulose purity. These processes are water, energy, and cost-intensive and make use of several chemicals to achieve a finished product of desirable quality. At the same time, these processes generate significant quantities of waste, thereby posing environmental concerns. The current focus of dissolving pulp production is centred on the development of environmentally friendly processes or advancements in existing processes to reduce environmental impact and improve production efficiency at modest capital investments. In this paper, a comprehensive review of the literature was undertaken to evaluate existing technologies and identify emerging ones in the field of dissolving pulp production. The review is purposeful in providing a concise understanding of dissolving pulp production and outlines the relative strengths and weaknesses of existing and novel processes and helps individuals keep abreast of the latest trends in the field. Furthermore, a brief overview of biorefinery opportunities emerging from dissolving pulp processes and their respective applications are provided. [ABSTRACT FROM AUTHOR]

Xylan is the main contaminant of hardwood sulphite dissolving pulp used for the production of regenerated cellulose. The amount of xylan in pulp should not exceed the minimum allowable values and which is not easy to achieve. To control the pulping process, a basic knowledge of xylan removal is essential. In this study, Eucalyptus globulus glucuronoxylan (GX) conversion during acidic Mg-base acid sulphite pulping of dissolving pulp was assessed for the first time in pilot experiments simulating the industrial process. The kinetics of GX degradation and changes in its structure and molecular weight along all pulping steps were evaluated. According to pentosans analysis, more than 60% of wood xylan was removed already in the heating-up step. A pseudo-first-order reaction for xylan degradation at the final pulping temperature of 140–148 °C was obtained with an activation energy of 133.4 kJ/mol. Removal of residual GX from pulp was hampered by its entrapment in cellulose fibril aggregates. The dynamics of xylan deacetylation and depolymerization during pulping in isolated samples was revealed by 2D NMR and SEC techniques, respectively. Overall, the residual xylan structure in pulp is predetermined by its structural heterogeneity in the cell wall, rather than by structural changes occurring during pulping. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There is increasing attention to the production of cellulose nanocrystals (CNCs) from lignocellulosic biomass by enzymatic hydrolysis with cellulase. In this study, the feasibility of the application of a cellulase system from engineered strain Penicillium oxalicum cEES in the production of CNCs was assessed. Using commercial eucalyptus dissolving pulp (EDP) as substrate, the CNCs were successfully obtained by enzymatic hydrolysis with the cellulase cEES, and the total yields of CNCs reached 15.7% through three-step enzymatic hydrolysis of total 72 h (24 h for each step). The prepared CNCs were characterized and found that their crystallinity and thermal stability were higher than that of EDP. In the later stage of enzymatic hydrolysis, the process efficiency of enzymatic preparation of CNCs greatly decreased because of the high crystallinity of cellulosic substrate, and a simple homogenization treatment can promote the enzymatic hydrolysis, as well as produce fusiform CNCs with more uniform size and more fermentable sugar that could be further converted into fuels and bulk chemicals through fermentation. This study provides a feasible enzymatic preparation process for CNCs with engineered cellulase and commercial cellulosic materials. [ABSTRACT FROM AUTHOR]

As an alternative raw material for various cellulose derivatives, the current research studied the processing of old corrugated container (OCC) in the subsequent stages of homogenization (soda cooking) and purification (bleaching with hypochlorite). The properties were characterized in four different categories including chemical composition or purity, accessibility, reactivity, and structural features. Alkali delignification and a bleaching sequence of HEHEHEA were selected for homogenization and purification of pulp followed by characterization of the pulp properties. The dissolving pulp exhibited the following properties: yield, 78%; cellulose, hemicellulose, and lignin content, 90.5%, 7.76%, and 0.3%, respectively; alpha cellulose, 70%. Pulp reactivity measured with two experiments showed Fock reactivity value of 85.67% as well as iodine sorption value (ISV) of 94.95 g/g; accessibility represented by two tests of water retention (WRV) and alkali retention capacity (ARC) with 6.87 for the first and 6.1% for the latter, degree of polymerization (DP), 913.4; crystallinity index, 76.95%; and brightness, 72.87%. FTIR spectroscopy and Brunauer-Emmet-Teller (BET) isotherms were utilized to examine the modifications of OCC to dissolving pulp. The results indicated that the dissolving pulp produced from OCC as a raw material is suitable for DP applications of cellulose derivatives.

Hemicellulose and lignin are not reasonably utilized during the dissolved pulp preparation process. This work aimed to propose a process for the co-production of dissolving pulp, furfural, and lignin from eucalyptus. High-grade dissolving pulp was prepared from eucalyptus using a combination of extremely low acid (ELA) pretreatment, Kraft cooking, and elementary chlorine-free (ECF) bleaching. The obtained pre-hydrolysate was catalytic conversion into furfural in a biphasic system, and lignin during Kraft cooking and ECF was recovered. The process condition was discussed as well as the mass flow direction. The results showed that ELA pretreatment could effectively remove 80.1% hemicellulose. Compared with traditional hydrothermal pretreatment, the ELA pretreatment significantly increased the xylose yield from 5.05 to 14.18 g/L at 170°C for 2 h, which had practical significance for furfural production. The 82.7% furfural yield and 82.9% furfural selectivity were obtained from xylose-rich pre-hydrolysate using NaCl as a phase modifier in a biphasic system with 4-methyl-2-pentanone (MIBK) as an organic phase by ion exchange resin catalysts at 190°C for 2 h. Subsequently, the pretreated eucalyptus was subjected to Kraft cooking, and the optimal alkali amount was 14%. Then, the Kraft pulp was bleached using the O-D1-EP-D2 sequence, and dissolving pulp was obtained with an ISO brightness of 86.0%, viscosity of 463 mL/g, and α-cellulose content of 95.4%. The Kraft lignin which has a potential application was investigated by 2D-HSQC NMR and 31P NMR. The results showed that the S/G ratio of Kraft lignin was 1.93, and the content of phenolic hydroxyl groups was 2.53 mmol/g. Moreover, based on the above proposed process, 30.5 g dissolving pulp, 5.5 g furfural, and 21.2 g lignin per 100 g eucalyptus chips (oven dry) were produced. This research will provide new catalysis and pulping technical routes for dissolving pulp, furfural, and Kraft lignin products, which are in great demand in the chemical industry. [ABSTRACT FROM AUTHOR]

In this study, dissolving pulp was prepared from corncob via alkali extraction, kraft cooking, metal ion removal, and H2O2 bleaching. Two cooking schemes were used to prepare unbleached corncob pulp samples with degrees of polymerization of 735 and 565. Employing an acid treatment with sodium ethylenediamine tetraacetate (EDTA) and sodium hexametaphosphate (SHMP) effectively reduced the ash and iron contents of the pulp; the optimal treatment conditions were pH 1.5, 0.4 wt% EDTA, and 0.4 wt% SHMP, which afforded pulp with iron and ash contents of 8.5 ppm and 0.02 wt%, respectively. A single-factor experiment was used to study the effects of H2O2 dosage and bleaching time on the brightness of the obtained pulp. The optimal bleaching parameters were determined as an H2O2 dosage of 3 wt% and a bleaching time of 70 min, which led to a brightness value greater than 82%. Fourier transform infrared spectroscopy and scanning electron microscopy results confirmed that the main component of corncob pulp was cellulose, and the fiber adopted twine-like morphologies with numerous spiral folds on the surface. The wet corncob pulp was used directly as the raw material for spinning lyocell fibers, and the results indicated that the corncob pulp had good spinnability. [ABSTRACT FROM AUTHOR]

Regioselective C6 and C2,C3 carboxylated cellulose nanofibrils (CNFs) have been robustly generated from dissolving pulp, a readily available source of unmodified cellulose, via stoichiometrically optimized 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO)-mediated and sequential sodium periodate-sodium chlorite (PC) oxidation coupled with high-speed blending. Both regioselectively optimized carboxylated CNF series possess the widest ranges of comparable charges (0.72–1.48 mmol/g for T-CNFs vs. 0.72–1.10 mmol/g for PC-CNFs), but similar ranges of thickness (1.3–2.4 nm for T-CNF, 1.8–2.7 nm PC-CNF), widths (4.6–6.6 nm T-CNF, 5.5–5.9 nm PC-CNF), and lengths (254–481 nm T-CNF, 247–442 nm PC-CNF). TEMPO-mediated oxidation is milder and one-pot, thus more time and process efficient, whereas the sequential periodate–chlorite oxidation produces C2,C3 dialdehyde intermediates that are amenable to further chemical functionalization or post-reactions. These two well-characterized regioselectively carboxylated CNF series represent coherent cellulose nanomaterial models from a single woody source and have served as references for their safety study toward the development of a safer-by-design substance evaluation tool.

The need of dissolving pulp (DP) for rayon fiber production is increasing rapidly in recent years. Sustainable sources of DP raw materials and an effective manufacturing process are urgently required. This study aims to manufacture dissolving pulp (DP) with high brightness from Sansevieria-trifasciata (ST) fiber through the pre-hydrolysis, soda-Anthraquinone (Soda-AQ) cooking, and chlorine-free bleaching processes. The cellulose content, kappa number, pulp yield, and viscosity were analyzed. The results showed that the ?-cellulose content in ST raw material (39.43%) was relatively similar to the ?-cellulose content in Acacia pulping kraft (39.2%). Furthermore, the variations in pre-hydrolysis time affected the Kappa number, pulp yield, and viscosity. The DP obtained by the elementary chlorine-free (ECF) bleaching process had a viscosity of 9.3 cP, ?-cellulose content of 97.7%, and the brightness of 90.1% which was higher than the ISO standard of pulp brightness. The high DP brightness obtained from this unique combination of pre-hydrolysis, soda-AQ cooking and chlorine-free bleaching sequences has great potential for further development, as it can be used in viscose rayon staple fibers production.

Improving the cellulose accessibility and reactivity in an efficient and convenient way has become the focused issue in the field of dissolving pulp manufacturing. We herein demonstrate a simple yet efficient strategy, namely a simultaneous microwave (MW)-assisted phosphotungstic acid (PTA) catalysis (MW-PTA sim). The MW-PTA sim treatment was efficient to improve Fock reactivity from 49.1 % to 85.8 % and decrease viscosity from 561 to 360 mL/g within 10 min, which was superior to the single MW treatment and the sequential MW-PTA seq treatment. Besides, the MW-PTA sim treated fiber had rougher and more fibrillated surfaces with an enhanced fiber accessibility, showing increased specific surface area (SSA) from 1.43 to 6.31 m2/g, mean pore diameter (MPD) from 6.92 to 11.20 nm and water retention value (WRV) from 101 % to 172 %. These positive enhancements are mainly due to a synergy that MW-enhanced rotation of PTA mediums was served as "spinning cutters" to attack the fibers, plus MW-accelerated PTA transfer and catalytic hydrolysis further improved the fiber accessibility. Moreover, PTA also demonstrates a high reusability and chemical stability. This process offers an effective and sustainable alternative for manufacturing a premium dissolving pulp. [Display omitted] • A simultaneous treatment for an enhanced reactivity of dissolving pulp was developed. • The treatment (MW-PTA sim) consisted of microwave radiation and PTA catalysis. • A synergy in the simultaneous treatment contributed to the enhanced pulp reactivity. • The recycled PTA maintained a high catalytic activity after several cycles. [ABSTRACT FROM AUTHOR]

Biodegradable thermoplastic starch (TPS) has been expected to be sustainable alternative to petrochemical-based polymers due to its biodegradability with proper and controlled costs. However, brittleness and biodegradation rate of TPS are insufficient for usage as a single material. The present work aims to improve TPS properties by incorporating with unvulcanized natural rubber (NR), epoxidized NR with 25 and 50 mol% epoxide (ENR25 and ENR50) and 0–15 phr of dissolving pulp (Fiber) using combined techniques of internal mixer and compression molding at 180 °C. The results based on mechanical properties, water resistance, biodegradation and thermal stability of TPS were studied. It was found that the tensile properties, following ASTM D638 Type I, increased after the addition of ENR25 relative to the NR and ENR50 cases. In addition, the combination of 10 wt% ENR50 and 15 phr fiber to the TPS showed high potential on improvement of tensile properties of the composites relating polarity effects. This blending ratios also enhanced the thermal stability of the composites, relating the thermogravimetric analyzer (TGA), whereas the solubility and disintegration in terms of the dimensions and shape of the TPS after water and soil exposure were reduced monitoring through weight loss investigation. This means that the incorporation of ENR50 and fiber at 10 wt% and 15 phr, respectively, to the TPS properly showed a synergistic effect on increasing of TPS properties by increasing flexibility and retarding biodegradation rate after soil exposure for 60 days. This environmentally friendly materials could be use as seed tray, slow released fertilizer for agriculture applications. [ABSTRACT FROM AUTHOR]

As an alternative raw material for various cellulose derivatives, the current research studied the processing of old corrugated container (OCC) in the subsequent stages of homogenization (soda cooking) and purification (bleaching with hypochlorite). The properties were characterized in four different categories including chemical composition or purity, accessibility, reactivity, and structural features. Alkali delignification and a bleaching sequence of HEHEHEA were selected for homogenization and purification of pulp followed by characterization of the pulp properties. The dissolving pulp exhibited the following properties: yield, 78%; cellulose, hemicellulose, and lignin content, 90.5%, 7.76%, and 0.3%, respectively; alpha cellulose, 70%. Pulp reactivity measured with two experiments showed Fock reactivity value of 85.67% as well as iodine sorption value (ISV) of 94.95 g/g; accessibility represented by two tests of water retention (WRV) and alkali retention capacity (ARC) with 6.87 for the first and 6.1% for the latter, degree of polymerization (DP), 913.4; crystallinity index, 76.95%; and brightness, 72.87%. FTIR spectroscopy and Brunauer-Emmet-Teller (BET) isotherms were utilized to examine the modifications of OCC to dissolving pulp. The results indicated that the dissolving pulp produced from OCC as a raw material is suitable for DP applications of cellulose derivatives. [ABSTRACT FROM AUTHOR]

Lyocell fiber has emerged as a new generation of green fiber due to its preparation process and unique properties in comparison with viscose fiber. The raw material for the preparation of Lyocell fiber has a great impact on the quality of the finished product. However, unlike viscose-grade dissolving pulp, there is no evaluation system for Lyocell-grade dissolving pulp, making it difficult to assess the quality of the raw material. This study examined the approach to upgrade the paper-grade pulp to dissolving pulp for the preparation of the raw material for Lyocell fiber. Under the sequence of caustic extraction, acid treatment, and enzymatic treatment, the pulp was prepared with competitive properties compared to the commercial Lyocell-grade dissolving pulp. The assessment of prepared pulp was also accomplished by characterizing the pulp properties, the dissolution properties, and the spinnability and stability of Lyocell solution using the prepared sample. In addition, the dissolution mechanism and influencing factors of pulp in the system were elucidated, providing a theoretical basis for upgrading paper-grade pulp to dissolving pulp for Lyocell fiber production. [ABSTRACT FROM AUTHOR]

The dissolving pulp preparation from bleached kraft pulp while realizing the high-value application of hemicellulose fraction is of great significance for improving the overall economics of the process. This work proposed a two-step cascaded process of deep eutectic solvent (DES) pretreatment combined with mechanical refining for the co-production of dissolving pulp and arabinoxylan (AX) from bleached bamboo pulp. Results showed that using alkaline DES composed of quaternary ammonium hydroxide and urea prepared high-quality dissolving pulp (α-cellulose content of 97.7 %) while selectively extracting high-quality AX. The mechanical refining rapidly opened up the cellulose structure to increase its Fock reactivity to over 70.0 %. When 100 g bleached bamboo pulp was subjected to this technology route, the high yields of dissolving pulp (63.8 g) and AX (13.0 g) were respectively obtained. It was proposed that the tailored DES with different alkalinity could specifically produce dissolving pulp or AX which were more favorable for downstream application through distinct action pathways. The swelling effects of DES on the cellulose surface facilitated the subsequent mechanical fibrillation, allowing a synergistic enhancement of the reactivity. Thus, the integrated process provided a sustainable alternative for dissolving pulp upgrading while adding attractiveness by co-producing AX product stream. Schematic diagram of alkaline DES pretreatment combined with mechanical refining synergistically preparing high-quality dissolving pulp and arabinoxylan. [Display omitted] [ABSTRACT FROM AUTHOR]

Wood properties for dissolving pulp production are little explored in wood quality research, mainly when it comes to eucalyptus trees. Therefore, the objective of the present study is to assess age and genotype impact on the quality of wood from young eucalyptus clones aimed at dissolving pulp production. Five trees from two clones, Eucalyptus urophylla (A) and E. urophylla x E. spp. (B), at the ages of 3 and 5 years, from crops located in Itanagra and Alagoinhas, Bahia State, Brazil, were assessed. Three wooden discs were removed from six trees at positions 0 %, 25 %, 50 %, 75 % and 100 % diameter at breast height (DBH) of the commercial height set for macroscopic characterization and wood chemical, physical and anatomical properties. Material age had impact on heartwood and bark production; and extractives, ash, xylans, galactans, arabinans rates, as well as wood vessels' diameter and frequency. Genotypes had impact on extractives, lignin ash, hemicelluloses, xylans and galactans levels. Thus, wood chemical composition was the property most influenced by factors 'age' and 'genotype'. Furthermore, clone A, at the age of 5 years, was the one with the greatest potential to dissolving pulp production, based on the following findings: the highest basic density (450 kg.m³), the highest glucans rate (48 %) and the lowest hemicellulose concentration (23 %). [Display omitted] • Age and genotype played important role in eucalyptus wood properties. • Wood chemical composition was the property most influenced by factors 'age' and 'genotype. • Eucalyptus urophylla (Clone A), at the age of 5 years, was the one with the greatest potential to dissolving pulp production. • Provided valuable information to optimize future dissolving pulp sustainable production strategies. [ABSTRACT FROM AUTHOR]

[Display omitted] • An integrated process of fiber fractionation and DES treatment is proposed for bamboo pulp upgradation. • Fiber fractionation separates the parenchyma cells to improve fiber homogeneity. • DES treatment facilitates the fiber swelling and hemicellulose removal. • The upgraded acetate-grade bamboo dissolving pulp has a high reactivity and acetylation. The production of high purity cellulose and its derivates from bamboo is appealing to agroforestry industry in China. However, the inhomogeneity and recalcitrance of bamboo pulp hinder its purification, rendering a poor reactivity and an inferior quality. In this study, we propose an integrated process, involving fiber fractionation (FF) and deep eutectic solvent treatment (DES), for overcoming the nonuniformity and low reactivity of the bamboo kraft pulp (BKP) as to develop it into a high-quality cellulose acetate (CA)-grade dissolving pulp. Results show that the fiber fractionation can develop two more uniform fiber fractions, namely the short-fiber (SF, parenchyma cells and fines) and the long-fiber (LF, bamboo fibers). Thanks to the fiber fractionation, the LF has a higher fiber accessibility, thus facilitating the mass transfer and reaction efficiency during the DES (ChCl-OA) treatment. Moreover, the DES treatment further improves the properties of LF in terms of purity (from 88.9 % to 95.1 %) and reactivity (from 43.0 % to 94.6 %). As a result, the regular BKP fiber can be upgraded to the CA-grade with a high substitution of 2.87 and a yield of 50.1 %. [ABSTRACT FROM AUTHOR]

Converting paper-grade bleached Kraft pulp into dissolving pulp using eco-friendly chemicals on-site at the mill is a challenge for the pulp industry. In this study, two oxidation systems are evaluated: the first one is based on the use of hydrogen peroxide at various levels of alkalinity; the second one investigates the use of sodium periodate followed by hydrogen peroxide to convert aldehydes into carboxyls and enhance their hemicelluloses removal. Our results have shown that when using only peroxide, the removal of hemicelluloses was not sufficient to improve the pulp’s dissolving ability. Conversely, the periodate–peroxide system proved to be more efficient. Results regarding the pulp purity, solubility, degradation (pulp viscosity and cellulose molecular mass distribution), brightness, and its potential applications were discussed.

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the sulphur oxide anions profile at all stages of the Mg acid sulphite pulping process was evaluated by Ion Chromatography (IC). The concentration of bisulphite anions decreased almost two-third along the cooking, while the sulphate concentration increased progressively. Of the bisulphite consumed, only a third was converted to sulfates. Unexpectedly, the maximum thiosulphate concentration was found in the pulping acid filling step, being further decreased along the cooking. The chloride ions rise progressively during the cooking being extracted essentially from the wood, although a noticeable part of the phosphate anions belongs to pulping reagents and inlet water. The low molecular weight fraction of lignosulphonates (LS) appeared in the cooking liquor in the residual delignification step and, together with xylonic acid, contributed to an overestimation of the fluoride concentration determined by the IC due to the same retention time in the chromatographic column during the analysis. [ABSTRACT FROM AUTHOR]

Valorization of non-wood pulp, such as bamboo bleached kraft pulp into high-purity cellulose acetate (CA)-grade dissolving pulp is crucial but challenging in China. Herein, a series of metal salt-based deep eutectic solvents (MSDESs) involving various ZnCl 2 -urea (U), ZnCl 2 -glycerol (G), and ZnCl 2 -lactic acid (LA) are comparatively investigated for this purpose. Thanks to the bifunctional acid sites of Lewis acid ZnCl 2 and Brønsted acid LA, the ZnCl 2 -LA MSDES has the highest acidity (2.62) and interaction affinity to bamboo fibers, leading to the highest efficiency in simultaneous pulp purification and activation. As a result, the resultant upgraded pulp from ZnCl 2 -LA (DES3-F) features remarkable improvements in purity (from 80.8 % to 93.1 %), intrinsic viscosity (from 897 to 419 mg/L), and reactivity (from 18.1 % to 80.8 %). Moreover, the modified acetate product has a high degree of substitution of 2.84 and a yield of 75.5 %. In short, such a proposed MSDES treatment can offer a promising and alternative approach for the manufacture of high-quality dissolving pulp and its derivatives. [Display omitted] • Metal salt deep eutectic solvent (MSDES) with ZnCl 2 -based Lewis acid is prepared. • ZnCl 2 -lactic acid (LA) with bifunctional acid sites features the highest acidity of 2.62. • ZnCl 2 -LA has simultaneous purification and activation mechanisms for bamboo pulp. • The upgraded acetate-grade bamboo dissolving pulp has a high reactivity of 80.8 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • 50 % of lignin is removed in the impregnation and heating-up sulphite cooking steps. • Bulk delignification in acid sulphite cooking follows first order kinetics. • Delignification is promoted by H+ and inversely proportional to combined SO 2. • Lignin accessibility plays a crucial role in the acid sulphite pulping. • Minimum degree of lignin sulphonation to be dissolved in the pulping liquor is 0.35. The kinetics of Eucalyptus globulus wood delignification in Mg-base acid sulphite pulping of dissolving pulp was studied using a pilot-scale batch digester simulating the industrial process. The behavior of lignin during impregnation, heating-up and bulk delignification at the final temperature was evaluated by the analysis of acid-insoluble lignin in wood and wood residue after pulping. The dynamics of lignin dissolution was followed by its structural analysis in solid residues and in solution by wet chemistry and 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. About 30 % and 20 % of the lignin were removed in the impregnation and heating-up pulping steps, respectively. About 45 % of the lignin was removed at the final pulping temperature in bulk and 3 % in the residual delignification stages. The kinetics of bulk delignification followed a pseudo-first-order kinetics with an effective activation energy of 138.4 kJ/mol in the temperature range of 140–148 °C. Bulk delignification follows an undefined overall order in the hydrogen and bisulfite ions and depended on the partial pressure of SO 2 at ca. 0.60 order within the range of combined SO 2 in pulping acid of 1.14–1.66 % and total SO 2 loads of 6.2–7.0 %. Minimum degree of lignin sulphonation to be dissolved in the pulping liquor was suggested to be about 0.35 sulphonic groups per one phenyl propane unit. Lignin removal during pulping showed dependence on its location in different morphological parts of the fibers and related structural characteristics, which were discussed accordingly. A role of the polysaccharide complex in the accessibility of lignin was highlighted. A noticeable cleavage of β- O -4 linkages occurred in lignin already dissolved in pulping liquor at the end of cooking. [ABSTRACT FROM AUTHOR]

The main challenges in the conversion of a paper-grade pulp and producing dissolving-grade pulp are the selective removal of hemicelluloses and the high pulp reactivity ([13]; [24]; Kopck 2010; [25]; [33]). Dissolving pulps are chemically refined bleached pulps that exhibit high cellulose content (over 90%) with advantageous properties such as high purity, high brightness, uniform molecular mass distribution and high cellulose reactivity, which represents a significant niche in the pulp industry ([24]; [25]; [26]; [35]; [43]). Keywords: bagasse soda pulp; cold caustic extraction; dissolving pulp; IONCELL-P(ulp); xylanase EN bagasse soda pulp cold caustic extraction dissolving pulp IONCELL-P(ulp) xylanase 473 483 11 05/09/22 20220501 NES 220501 1 Introduction Human dependence on petroleum-based products has raised concerns due to the negative impacts on the environment. [Extracted from the article]

In this study, we investigated the influence of hemicelluloses removal treatment on the reactivity of the resulting pulp. The idea was to develop treatment strategies consisting of mechanical refining (different refining technologies), chemical treatment (CCE), and xylanase treatment that enabled both quantitative xylan removal as well as good reactivity to dissolution without the need for additional post-extraction treatments (cellulose activation) to improve reactivity. Cellulose post-extraction treatments result in additional production costs. The reactivity of the extracted pulps was evaluated based on the degree of swelling in NaOH and dilute cupriethylene diamine solution (CUEN), the solubility in 8% NaOH at -10 °C, and the Fock reactivity. The result obtained showed that hemicelluloses removal strategies that included mechanical refining treatment led to better pulp reactivity than unrefined pulp. The best result was obtained with refined pulp extracted with 6% soda (cellulose II not detected). In addition, we obtained a Fock reactivity ranging from 60 to 70%. The good correlations found between fiber swelling, solubility in caustic soda, and Fock reactivity suggest that the tedious Fock test could be substituted by the much simpler swelling and solubility measurements. The negative impact of cellulose II on pulp reactivity is due to the higher number of hydrogen bonds formed under dewatering and drying. This problem would most likely be averted in the ideal case where pulp dissolution is integrated into the pulp mill.

One of the common applications of cellulosic fibers as dissolving pulp production requires high purity. Different cellulosic fiber sources are used to produce dissolving pulp. Due to deforestation and lack of agricultural land and problems with cultivation, the use of wood and non-wood sources of such fibers is declining. Another source of cellulose is recycled pulp. Chlorine dioxide acts as a completely selective bleaching chemical. Increasing kappa factors is very effective in removing lignin levels. In this research, dissolving pulp from recycled fibers is obtained using soda cooking and bleaching with chlorine dioxide. Then, the effect of changes in kappa factor of the second stage of chlorination on chemical composition (holocellulose and lignin), structural properties (degree of polymerization, alpha-cellulose and degree of brightness) and accessibility (water retention value) are investigated. The results showed that the degradation of holocellulose levels was not severe and did not cause cellulose damage and decreased alphacellulose levels as well as the degree of polymerization. The removal of lignin as a hydrophobic component and the presence of hemicellulose as a hydrophilic component increase accessibility (water retention) and decrease brightness degree. [ABSTRACT FROM AUTHOR]