Sulfite Pulp Research Articles

Catalytic influence of alkali and alkali earth metals in black liquor on the gasification process: a review

AbstractDuring the pulping process, either alkali or alkali earth metals are added in a cooking solution to turn wood chips into pulp, and these alkali and alkali earth metals (AAEMs) end up in the black liquor. These AAEMs are known to catalyze the gasification process, by lowering the reaction temperature and degrading tar in the syngas. Of the various black liquor valorization methods, gasification is a promising process that can be integrated into existing pulping processes to recover the process energy via syngas utilization. It is, therefore, important to firmly understand how AAEMs in black liquor catalyze the gasification process. This review paper also discusses how black liquor is generated from both the Kraft pulping and the sulfite pulping process. The paper also examines advances that have been made in terms of an integrated gasification process into the existing pulping process. The paper explores the supercritical water gasification of back liquor and syngas as fuel in the pulp and paper industry. A discussion of the co-gasification of black liquor with either fossil fuels or biomass, focusing on the catalytic effect of AAEMs in the co-gasification process as well as the synergistic effects of fossil fuels and biomass is presented.

Synthesis of Highly Porous Lignin-Sulfonate Sulfur-Doped Carbon for Efficient Adsorption of Sodium Diclofenac and Synthetic Effluents.

Herein, a novel sulfur-doped carbon material has been synthesized via a facile and sustainable single-step pyrolysis method using lignin-sulfonate (LS), a by-product of the sulfite pulping process, as a novel carbon precursor and zinc chloride as a chemical activator. The sulfur doping process had a remarkable impact on the LS-sulfur carbon structure. Moreover, it was found that sulfur doping also had an important impact on sodium diclofenac removal from aqueous solutions due to the introduction of S-functionalities on the carbon material's surface. The doping process effectively increased the carbon specific surface area (SSA), i.e., 1758 m2 g-1 for the sulfur-doped and 753 m2 g-1 for the non-doped carbon. The sulfur-doped carbon exhibited more sulfur states/functionalities than the non-doped, highlighting the successful chemical modification of the material. As a result, the adsorptive performance of the sulfur-doped carbon was remarkably improved. Diclofenac adsorption experiments indicated that the kinetics was better described by the Avrami fractional order model, while the equilibrium studies indicated that the Liu model gave the best fit. The kinetics was much faster for the sulfur-doped carbon, and the maximum adsorption capacity was 301.6 mg g-1 for non-doped and 473.8 mg g-1 for the sulfur-doped carbon. The overall adsorption seems to be a contribution of multiple mechanisms, such as pore filling and electrostatic interaction. When tested to treat lab-made effluents, the samples presented excellent performance.

Investigation of cellulosic fines removal in dissolving pulp production with small-holed screen plates

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.

New insights into kinetics and mechanisms of acid sulphite delignification of Eucalyptus globulus wood

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 SO2 at ca. 0.60 order within the range of combined SO2 in pulping acid of 1.14–1.66 % and total SO2 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.

Enhancing the valorization of pulping black liquors in production effective aerogel–carbon nanostructure as adsorbents toward cationic and ionic dyes

This work deals with promoting the efficiency of removing the cationic and ionic dyes by new aerogel–carbon nanostructures. For cleaner production the rice straw-pulping black liquors, which regards serious environmental risk during routine disposing, is used in preparing the aerogel precursors. These aerogels (AGBs) depend on using pulping black liquor in hybrid with resorcinol and the less carcinogenic formaldehyde butyraldehyde. Black liquors from five pulping processes are used, Elemental, thermogravimetric (TGA and DTG), and FTIR-ATR analyses are used to characterize the carbon precursors. While their adsorption behavior toward cationic and anionic dyes are accessed via iodine-value, adsorption capacity and kinetic models, textural characterization, and SEM. The TGA measurements reveal that AGBs from BLs of neutral sulfite and soda-borohydride pulping reagents have higher activation and degradation energies than other aerogels. In terms of cationic and anionic dyes adsorption as well as textural characterization, the AGB-CNSs surpass that made from BLs. The discarded KOH/NH4OH black liquor is used to synthesize the best aerogel precursor for producing cationic methylene blue dye (MB) adsorbent, where it provides an adsorption capacity 242.1 mg/g. The maximum anionic brilliant blue dye (BB) adsorption capacity, 162.6 mg/g, is noticed by Kraft BL-aerogel-CNSs. These finding data overcome the literature carbon adsorbents based on lignin precursors. All examined CNSs toward MB dye follow the Langmuir adsorption equilibrium; while primarily the Freundlich model for BB dye. The pseudo-second-order kinetic model well fits the adsorption kinetics of investigated AGB-CNSs. The textural characterization and SEM revealed a mixture of mesoporous and micro porous features in the CNSs.

Synthesis of 3, 3′- bis (indolyl) methanes using Bio-Waste metal free super acid as efficient with recyclable catalysts

A bio-waste metal free sulfonated carbonaceous super acid catalyst (BWC) is generated from sodium lignosulphonate, which is obtained from bio-waste sulphite pulping process of paper making industries. Here, we report a highly efficient catalytic a sulphonated carbon material catalyzed electrophilic substitution reactions of indoles with aromatic aldehydes to afford 3,3′-bisindolylmethane (BIM) derivatives. The synthesized BIM compounds were characterized by modern analytical techniques like NMR, MS, FT-IR, CHNS analysis. The BWC green catalyst was characterized by FT-IR, thermal gravimetric analysis (TGA) scanning electron microscopy (SEM), thermal electronic microscopy (TEM) with elemental analysis. The significant features of this catalysis are easy catalyst preparation, high product yields, environmental benignity, short reaction time, broad substrate scope, with use of non-toxic solvents. The catalysts could be recycled with reused three times without decrease in the catalytic activity significantly.

One pot green synthesis of Biginelli reaction catalysed by bio-waste metal-free super acid lignin sulphonate

A Bio-waste metal-free super acid catalyst (BWC) has been synthesized at higher temperature and used as a catalyst for synthesis of 3,4-dihydropyrimidine-2-(1H)-ones (DHPMs) via one pot three component Biginelli reaction. The multicomponent reactions are very complex and involves more than two reagents. In the present study, sulfonated carbonaceous material called a green catalyst was utilized for three component reaction. Catalyst was synthesized from sodium lignosulfonate which is obtained from the wastage of paper-making industries from the sulfite pulping process. The synthesized green catalyst was characterized by FT-IR, Thermal Gravimetric Analysis (TGA) scanning electron microscopy (SEM), Thermal Electronic microscopy (TEM), and elemental analysis. The three component Biginelli synthesis the catalyst was optimized to 8 mol % quantity which was sufficient to complete the reaction within 1–4 hrs. The yield of reaction ranges from 70-90 %. Separation was easy and recycling ability of catalyst was also tested with good retention of catalytical activity. Catalytic activity was performed as an acid-catalyzed reaction in ethanol. The synthesis of all the compounds were confirmed by 1H NMR (Nuclear magnetic resonance), MS (Mass Spectra), FT-IR (Fourier Transform Infrared), CHNS (Carbo, Hydrogen, Nitrogen, Sulphur) analysis. The satisfactory results were obtained with good yields, shorter reaction time and simplicity in the experimental procedure. The catalysts could be recycled and reused three times without decrease in the catalytic activity significantly.

Exploring Oxytenanthera abyssinica as a sustainable alternative for pulp and paper production: A response surface methodology approach for optimized soda pulping

Oxytenanthera abyssinica has been investigated as a possible substitute raw material for pulp and paper production because of its long fiber (2.40 mm), larger fiber width (21.83 μm), and flexibility ratio (0.72), smaller Runkel ratio (0.35), large slenderness ratio (109.98), and thinner cell wall thickness (2.74 μm). A response surface methodology (RSM) method was applied to explore and identify the best conditions for soda processing of the O. abyssinica stem. Soda concentration, cooking temperature, and cooking time were used to optimize the process of pulp production and the Kappa number (KPN). Under optimal conditions such as 180 min cooking time, 20 % active alkali, and 165 °C cooking temperature, the highest pulp yield and the lowest KPN were 43.48 % and 19.9, respectively. The optimized pulp was used to make a paper sheet having mechanical characteristics of the tensile index (28.23 Nm/g), tearing index (10.70 mNm2/g), and Burst index (1.11 kPam2/g). This study demonstrates that O. abyssinica pulp can produce paper with mechanical properties of medium strength equivalent to that of paper using a more environmentally friendly pulping process such as soda pulping compared to kraft and sulfite pulping. In summary, it can be inferred that O. abyssinica holds significant promise as a substitute raw material for pulp and paper industries. However, it is recommended to conduct pilot plant studies for further exploration.

AN EFFECTIVE RESOURCE-SAVING OPTION IN THE SPHERE OF WOOD PROCESSING AND ITS PROCESSING IN THE PULP AND PAPER INDUSTRY

The possibility and expediency of obtaining and bleaching sulfite pulp from young small-sized spruce wood from thinning (thinning) fellings was studied in comparison with ripe wood. In the process of thinning, a significant amount of young small-sized wood is formed, which can serve as a significant reserve of wood raw materials for the production of pulp and paper.
 Sulfite pulping from young and ripe spruce wood obtained two samples of pulp of different degrees of penetration.
 Comparative pulp bleachings were carried out according to the traditional economical but effective D/C-EG-G-D-A scheme; For comparison, pulp samples from ripe and young spruce wood were bleached according to the modern ecological scheme Pa-E-Ch1-E-Ch2-A (ECF technology). 
 It is shown that young small-sized spruce wood is delignified by sulfite cooking solution without difficulty, but somewhat more slowly than ripe wood.
 Sulfite spruce pulp obtained from thinnings is easier to grind and bleach, has higher mechanical strength than from ripe wood. Bleached pulp was obtained from young thin spruce wood by bleaching according to the scheme D/C–EG –G–D–A of pulp from young thin spruce wood, which in all quality indicators meets the standards for grade AK-II (GOST 3914), which is used mainly in the production of "cultural" grades of paper (written and printed). Comparative bleaching of pulp of approximately the same degree of penetration from ripe and young wood using ECF technology using only two oxidative bleaching agents (hydrogen peroxide and chlorine dioxide) significantly increases the efficiency of pulp bleaching in all quality indicators, but the cost of bleaching, in modern conditions, may be will be slightly higher than in the traditional scheme.

INFLUENCE OF CULTIVATION CONDITIONS ON CELLULASE AND XYLANASE ACTIVITY OF RHIZOPUS ORYZAE F-1030

The paper examines the relationship between the activity of cellulase and xylanase enzymes and the lactic acid yield which was synthesized by the fungus Rhizopus oryzae F-1030 during its cultivation on a culture medium based on catalytically modified neutral sulfite liquors. It was shown that in cultivating by the deep method the fungus R. oryzae F-1030 synthesizes xylanase and cellulase enzymes that break down polysaccharides in a nutrient medium to simple sugars which are easily accessible for assimilation by the fungus. Accordingly, the fungus R. oryzae F-1030 can be used as a promising biotechnological object for the bioconversion of cellulose production secondary resources. It was found that the level of cellulase and xylanase expression in R. oryzae F-1030 depends on the type of substrate. The xylanase activity of the fungus is more pronounced than the cellulase activity since xylan oligomers predominate in birch wood. It was noted that the lactic acid yield during the cultivation of the fungus R. oryzae F-1030 on a catalytically modified neutral sulfite liquor depends on the action specifics of the hydrolyzing catalyst. As a nutrient medium for the microbiological synthesis of lactic acid the fungus R. oryzae F-1030 can use biocatalytically treated liquors of birch wood neutral sulfite pulping.

UV-detoxification of spent sulfite liquor for polymerization of lignosulfonates and succinic acid fermentation with Actinobacillus succinogenes

Spent Sulfite Liquor (SSL), a byproduct of sulfite pulp production, contains lignosulfonates (LS) dissolved in a liquid phase rich in sugars, and phenolic substances. This study investigates the effects of UV-irradiation on SSL as a microbial substrate. UV-irradiation of SSL resulted in the polymerization of LS. The molecular weight of LS increased from 1949 Da to 5637 Da (at 3 days of irradiation). FTIR spectroscopy revealed structural changes, including an increase in phenolic OH groups and the formation of β-O-4 ether linkages. Batch fermentations with Actinobacillus succinogenes demonstrated that UV-irradiated SSL led to higher succinic acid production and reduced by-product formation. By product formation was reduced from 0.90 g byproduct per g succinic acid to only 0.62 g in irradiated media. Although the initial lag phase was longer for irradiated SSL, acid production eventually exceeded that of non-irradiated SSL and standard medium. Ultimately, a concentration of 14.40 g L-1 with a yield of 0.56 g of succinic acid per gram of consumed sugar was attained. This represented an increase of 3.01 g L-1 compared to standard media. In conclusion, UV-irradiation upgraded SSL by a higher specificity of succinic acid and allowing better utilization of LS in various applications through polymerization, aligning with sustainable production goals.

Influence of pulping conditions on the pulp yield and fiber properties for pulping of spruce chips by deep eutectic solvent

AbstractThe chemical pulping of wood chips using deep eutectic solvents (DES-pulping) has emerged as an alternative technology to conventional pulping in the paper industry, allowing the production of pulp in combination with the recovery of lignin and sugars for valorization. A challenge in the development of this technology is the understanding of how the operating conditions influence the crucial pulp manufacturing parameters such as delignification percentage, pulp yield, and fiber quality. This work is focused on investigating the effect of operating conditions such as cooking temperature, cooking time, liquor-to-wood ratio, initial water content on DES, type of mixing, the addition of a pre-treatment step (pre-impregnation of DES into the wood chips) to cooking process, and DES composition (lactic acid:choline chloride, lactic acid:sodium chloride, and lactic acid:sodium bromide) on the cooking of wood chips by DES. A shortcut quality evaluation parameter (Q), defined as the product of the fiber length and the degree of delignification quantified the quality of the pulping process in a single value, shows values similar to a reference unbleached kraft pulp for cooking at 130 °C in a range of cooking times from 3 to 4.5 h at a L/W of 10:1 by using lactic acid:choline chloride DES. More elaborate property analysis on the fibers showed that several of the the quality-indicating properties of the fibers (coarseness, shape factor, fibril area, and crill index) are comparable with typical sulfite pulping fibers.

LIGNOCELLULOSE BIOMASS DELIGNIFICATION USING ACID HYDROTROPE AS GREEN SOLVENT: A MINI-REVIEW

"Efficient and cost-effective conversion of lignocellulosic biomass into usable forms of energy presents unique challenges. Lignocellulosic biomass, comprising cellulose, hemicelluloses, and lignin, necessitates advanced conversion technologies. Common commercial delignification techniques, including kraft pulping, sulfite pulping, acid hydrolysis, and organosolv pulping, often involve harsh conditions leading to structural changes in lignin and environmental impacts. To address these issues, acid hydrotropes have emerged as a promising method for lignin extraction. Acid hydrotropes, represented by p-toluenesulfonic acid (p-TsOH), enable the solubilization of hydrophobic substances like lignin. This mini-review provides an overview of various lignocellulose fractionation techniques and explores the acid hydrotrope approach. The mechanism behind acid hydrotropic fractionation is discussed, and its performance is evaluated. In conclusion, the review emphasizes the pivotal role of the acid hydrotrope approach in advancing lignocellulosic biomass conversion technology, promoting a sustainable and efficient bio-based economy."

Enzymatic Hydrolysis of Kraft and Sulfite Pulps: What Is the Best Cellulosic Substrate for Industrial Saccharification?

Sulfite and kraft pulping are two principal methods of industrial delignification of wood. In recent decades, those have been considered as possibilities to pretreat recalcitrant wood lignocellulosics for the enzymatic hydrolysis of polysaccharides and the subsequent fermentation of obtained sugars to valuable bioproducts. Current work compares chemistry and technological features of two different cooking processes in the preparation of polysaccharide substrates for deep saccharification with P. verruculosum glycosyl hydrolases. Bleached kraft and sulfite pulps were subjected to hydrolysis with enzyme mixture of high xylanase, cellobiohydrolase, and β-glucosidase activities at a dosage of 10 FPU/g of dry pulp and fiber concentration of 2.5, 5, and 10%. HPLC was used to analyze soluble sugars after hydrolysis and additional acid inversion of oligomers to monosaccharides. Kraft pulp demonstrated higher pulp conversion after 48 h (74–99%), which mostly resulted from deep xylan hydrolysis. Sulfite-pulp hydrolysates, obtained in similar conditions due to higher hexose concentration (more than 50 g/L), had higher fermentability for industrial strains producing alcohols, microbial protein, or organic acids. Along with saccharification, enzymatic modification of non-hydrolyzed residues occurred, which led to decreased degree of polymerization and composition changes in two industrial pulps. As a result, crystallinity of kraft pulp increased by 1.3%, which opens possibilities for obtaining new types of cellulosic products in the pulp and paper industry. The high adaptability and controllability of enzymatic and fermentation processes creates prospects for the modernization of existing factories.

Transformations of glucuronoxylan during acid sulphite pulping of eucalyptus dissolving pulp

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.

Microcrystalline cellulose and by-products from the pulp and paper industry as reinforcing fibres for polybutylene succinate-based composites: A comparative study

This study focussed on the development of fully biodegradable composites based on polybutylene succinate (PBS) in combination with raw materials from different processing stages of the pulp and paper industry. Sulfite pulp (SP), kraft pulp (KP) and screened sludge residue (SL) from wastewater treatment plants (WWTP) were investigated as reinforcing fibres contributing to a circular economy. We report a comparative study of the physicochemical properties and mechanical performance of PBS composites reinforced with these cellulosic raw fibres and commercial pure microcrystalline cellulose (MC). The composites were characterised in tensile strength, elongation at break, modulus of elasticity, water absorption and wettability. The incorporation of the fibres into the polymer matrix was also investigated using torque rheometry. Critical concentrations were obtained with maximum incorporation in the range of 15–20 wt% for SP/KP and 25–30 wt% for SL. SP and KP composites showed at least as good physicochemical and mechanical properties as MC at the concentrations studied (0–20 wt%). SP-composites showed the highest tensile strength and modulus of elasticity. It was shown that these fibres from the pulp and paper industry can be used as reinforcement for PBS matrices without additional chemical purification and provide a valuable alternative to commercial microcrystalline cellulose.

Biochar‐based interfacial evaporation materials derived from lignosulfonate for efficient desalination

AbstractThe solar‐driven interfacial evaporation has attracted great attention for the purpose of alleviating freshwater shortage. Lignosulfonate (LS), a main byproduct of sulfite pulping processes, is an abundant natural resource but has not been reasonably utilized. To mitigate the above problems, biochar‐based interfacial evaporators derived from LS for solar steam generation were studied in this paper. First, LS was used as a raw material for fabricating carbon materials by carbonization to construct LS‐derived carbon (CLS). Meanwhile, LS‐derived porous carbon (PCLS) in the presence of CaCO3 as the activator was also prepared. Next, the two biochar powders, as solar absorbers, were crosslinked with polyvinyl alcohol to prepare the interfacial evaporation materials (PVA@PCLS and PVA@CLS). The open porous structure facilitated the capillary effect and water transport to the evaporator surface. It was also found that the light absorption of the materials could reach more than 97% in the 250–2500 nm range. Moreover, the water evaporation rate and the solar‐to‐vapor conversion efficiency of PVA@PCLS and PVA@CLS were 2.33, 1.82 kg m−2 h−1, and 83.7%, 69.3% respectively under 1 sun (1 kW m−2) irradiation. The solar‐to‐vapor conversion efficiency of PVA@PCLS was much increased after the carbonization of LS. In addition, the material cost of PVA@PCLS is only $38.3/kg due to the low price of LS. Therefore, this work provides an economic and efficient strategy for solar‐driven desalination and a possible way for the high‐value utilization of lignin.

New method for isolating β-sitosterol from bleaching effluent of sulphite pulp mill

β-sitosterol (BS) is a phytosterol with wide potential in cosmeceutical, biomedical and food applications. In acid sulphite pulp cooking, BS and its derivatives are considered an underutilized natural source of bioactive compounds, which are adsorbed on the resulting pulp or dispersed in the spent liquor. In this work, a new method for the isolation of BS from alkaline extract (AE) of unbleached sulphite pulp purification stage is proposed. BS was recovered by two-step acidification of AE up to pH 3 under pre-selected conditions, followed by fractionation of the formed precipitate with water-miscible organic solvents, having obtained best results (>90% of BS purity; yield of 70–210 mg/dm3 of AE) with methanol fractionation followed by BS crystallization induced via addition of water (ca. 10% vol.). When ethanol was used instead, BS was detected in low amounts in the isolate, being fatty acid sterol esters and fatty acid glycerides the major components, as revealed from analyses by wet chemistry coupled with gas chromatography-mass spectrometry and thin layer chromatography (TLC). The method is adaptable for large-scale industrial production of BS and may represent an important source of sterol-based products.

“Following a Simplified Scheme”: Project Development and Launch of Production at the Solikamsk Sulphite Pulp Mill

During the years of implementation of the first Soviet five-year plans, great attention was paid to the pulp and paper industry. In the forest industry structure, this component was characterised by a weak level of development. The bet was made on the creation of medium and large pulp and paper industries. In the Urals, where there were large reserves of forest resources and rivers, they built several plants. The largest centre of the pulp and paper industry in the Urals and in the eastern regions of the USSR was formed. The purpose of this article is to study the location, design, and launch of production of the Solikamsk Sulphite Pulp Mill. In the mid-1930s, it was decided to build an enterprise. The project involved innovative technological solutions for the pulp and paper industry. The launch of the plant was postponed several times, the project was altered, and the construction was entrusted from the People’s Commissariat of Forest Industry of the USSR to the People’s Commissariat of Internal Affairs of the USSR. In 1940, the Solikamsk Sulphite Pulp Mill became an independent enterprise, but its construction continued. In March 1941, three months before the outbreak of the Great Patriotic War, the company began the production of pulp. The production was only possible within a simplified scheme due to the absence or malfunction of equipment. The performance of the enterprise was set in insignificant volumes. With the outbreak of war, party-state bodies and economic departments continued the construction of the Solikamsk Sulphite Pulp Mill and providing additional equipment. The company’s development was boosted by the evacuation of several industries, the start of the sulphite waste liquor alcohol plant and the construction of a defense plant nearby. This allowed the plant to develop cooperative ties and master new types of products.

New solvent-free method for isolating ellagic acid from sulphite spent liquor

Ellagic acid (EA) is a plant polyphenol with wide potential in biomedical (e.g., anti-inflammatory, neuroprotective, and anti-melanogenic, among others) and technical applications such as copolymers, chelating reagents, ion-exchange resins and materials for electrochemical devices. Upon acid sulphite pulping of Eucalyptus wood, EA is partially dissolved in the spent liquor and adsorbed on the resulting pulp. In this work, a new solvent-free eco-friendly method for isolating EA from sulphite spent liquor and alkali extract of unbleached sulphite pulp is proposed. EA was recovered from sulphite pulping streams via crystallization from acidified solutions under preselected conditions (80 °C, 24 h, glass container and surface-to-volume ratio >1.0). The crystals obtained were washed with acidified water to reduce concomitants and increased EA purity from ca. 55–70% (w/w) to ca. 85–95% (w/w). The main contaminants of raw EA crystals were carbohydrates (ca. 15%), lignin (ca. 22%), lipophilic extractives (ca. 5%) and ash (ca. 3%). The obtained fractions were characterized by liquid and solid-state carbon nuclear magnetic resonance spectroscopy, mass spectrometry and wide-angle X-ray scattering, being the latter used to assess the crystalline structure. The purity of EA from sulphite spent liquor was much higher than that of the acidified alkaline extract of unbleached sulphite pulp obtained in the sulphite pulp purification step.