Kappa Number Research Articles

Optimization of kraft pulping process for Sesbania aculeata (dhaincha) stems using RSM

Abstract The shortage of superior grade wood fibers is a prime problem faced by Indian pulp and paper industries. As a result, the pulp and paper industry find it difficult to withstand the competition in the market, which had grown extremely competitive. In order to increase the utilization of non-wood fibers resources in the production of high quality eco-friendly papers, dhaincha, a non-wood fiber resource has potential industrial application. In this research, pulp and paper were developed from Sesbania aculeata stem using kraft pulping followed by bleaching. Optimization of conditions for pulping was carried out by Response Surface Methodology. The relationship between three variables and three responses were studied using Box–Behnken experimental design. The developed pulp was evaluated for kappa number, brightness index, viscosity, FTIR and TGA. Then paper was developed by using optimized pulp and evaluated for physical properties. The statistical analysis (ANOVA) was carried out in order to establish the relationship between the concentration of NaOH, Na2S, treatment time and temperature with kappa number, brightness index and viscosity. The physical properties of pulp and developed handmade paper highlights the sustainable use of dhaincha plant in pulp and paper industry.

Machine Learning Based Decision Support System for the Diagnosis of Breast Cancer

Breast cancer is among the most prevalent diseases encountered among women worldwide. Early diagnosis of breast cancer is crucial for the treatment of the disease. Detecting the disease at an early stage prevents deaths resulting from the condition. Recently, computer-aided systems have been developed to ensure early-stage diagnosis and accuracy of breast cancer. Computer-aided systems developed with machine learning approaches significantly contribute to the process of diagnosing breast cancer. The aim of this study is to propose a new classification system based on machine learning algorithms developed for the diagnosis of breast cancer. In this study, sub-data sets were created by reducing features, and data cleaning processes were applied. After these procedures, stages such as feature selection and feature extraction were applied. In this study, classification processes such as Ensemble, k- Nearest Neighbors (kNN), Support Vector Machines (SVMs), and Hybrid Artificial Intelligence were used in line with machine learning. With the obtained results, a Breast Cancer diagnosis algorithm was created. Performance evaluation criteria such as accuracy rate, specificity, sensitivity, kappa number and F-Measure were applied to the created algorithms. In the results obtained in this study, the highest accuracy rate was found to be 99.3% with the Ensemble method, the highest specificity rate was 98.7% with the Ensemble method, and the highest sensitivity rate was found to be 100% with many methods. In light of these results, it was observed that the machine learning algorithms used in this study, implemented in the Matlab environment, were effective. Consequently, it was proven that higher accuracy, specificity, and sensitivity rates can be found with different machine learning techniques. This also demonstrates that the study in our article is a reliable one in detecting diseased and healthy individuals in the diagnosis of breast cancer, showing that it is a more applicable and feasible study in the healthcare field.

Sodium carbonate pulping of oil palm empty fruit bunches for paperboard production

Abstract This study investigated the use of sodium carbonate pulping in oil palm empty fruit bunch (OPEFB) pulp production for paperboard manufacturing. The pulping varying the active alkali (AA) (4.5 %, 6.5 %, 8.5 %), NaOH fraction (F) (10 %, 20 %, 30 %), and cooking time (T) (30′, 60′, 90′). The performance was evaluated based on screened pulp yield, kappa number, and delignification selectivity. Furthermore, the functional groups, S/G ratio, and morphological structure of the optimum pulp were observed. The tensile and tear indices of the OPEFB pulp paperboard were also measured. The results suggest sodium carbonate pulping at a low chemical dose successfully produced OPEFB pulp. Based on the highest delignification selectivity value of 12.74, the most effective pulping conditions were achieved with AA-6.5 %, F-30 %, and T-90′. The optimum OPEFB pulp analysis revealed a decrease in lignin proportion with the dominant degradation of the syringyl unit. Thus, the fibers are easily separable during mechanical treatment. These characteristics influenced the paperboard, resulting high tensile and tear indices of 7.90–8.15 Nm g−1 and 15.09–16.25 mN m2 g−1, respectively. Overall, this study demonstrated the potential of sodium carbonate pulping to produce high-quality pulp and paperboard from OPEFBs, highlighting the thoroughness of the research process in the pulp and paper manufacturing field.

Production and characterization of pulp and paper from flax straw

Flax (Linum usitatissimum) is a bast fiber plant known for its long fibers, making it an excellent source of pulp for paper production. In Ethiopia, flax is primarily cultivated for oil, with the residual straw utilized for papermaking. This study focuses on pulping flax straw using the Kraft process and investigates its chemical composition, proximate analysis, and morphological properties. The proximate analysis revealed an ash content of 4.13% and moisture content of 11%. Chemical composition analysis showed cellulose at 51.34%, hemicellulose at 25.20%, lignin at 14.12%, ash at 4.13%, and extractives at 5.21%. The morphological properties included a fiber length of 1.41 mm, diameter of 16.78 μm, lumen width of 9.45 μm, and cell wall thickness of 3.77 μm. Flax straw exhibited an acceptable Runkel ratio (0.8) and flexibility coefficient (56.32), placing it within the range of non-wood fibers. SEM analysis of the pulp’s morphology was conducted to assess fiber structure, including the presence of cracks. Pulp quality and length are directly linked to paper strength. Various pulping conditions were studied using a full-factorial design, with optimum conditions being 10% alkaline, 131.74°C, and 120 min of cooking time, yielding a pulp with a Kappa number of 10.45 and a yield of 40.56%. The resulting paper demonstrated standard tensile, tearing, and burst strengths, indicating that flax straw is a promising raw material for paper production.

Control of continuous digester kappa number using generalized model predictive control

Kappa number variability at the digester impacts pulp yield, physical strength properties, and lignin content for downstream delignification processing. Regulation of the digester kappa number is therefore of great importance to the pulp and paper industry. In this work, an industrial application of model-based predictive control (MPC), based on generalized prediction control, was developed for kappa number feedback control and applied to a dual vessel continuous digester located in Western Canada. The problem was complicated by the need to apply heat at multiple locations in the cook. In this study, the problem was reduced from a multiple to a single input system by identifying three potential single variable permutations for temperature adjustment. In the end, a coordinated approach to the heaters was adopted. The process was perturbed and modeled as a simple first order plus dead time model and implemented in generalized predictive control (GPC). The GPC was then configured to be equivalent to Dahlin’s controller, which reduced tuning parameterization to a single closed loop time constant. The controller was then tuned based on robustness towards a worst-case dead time mismatch of 50%. The control held the mean value of the kappa number close to the setpoint, and a 40% reduction in the kappa number’s standard deviation was achieved. Different kappa number trials were run, and the average fiberline yield for each period was evaluated. Trial results suggested yield gains of 0.3%–0.5% were possible for each 1 kappa number target increase.

Effect of treating birch kraft pulp with peracetic acid before O2-delignification on the properties of pulp and consumption of ClO2 in D0ED1 bleaching

The influence of pre-treating Kappa number of 18.0 industrial birch kraft pulp with peracetic acid (Paa) before oxygen delignification (OD) was studied relative to the pulps’ level of delignification, yield, brightness, intrinsic viscosity (IV), FS-number, tear index (TI), and the consumption of chlorine dioxide (ClO2) in its subsequent Elemental Chlorine Free (ECF) bleaching. The study showed that such pretreatment is a way to extend the delignification of such pulp quite selectively in OD based on values of IV, FS-number, and TI, and to reduce significantly the consumption of ClO2 required to bleach this pulp to a brightness of 87%. This reduction depended on the amount of Paa used for pulp pretreatment. For example, when 0.33% and 0.66% as active oxygen (A.O.) of Paa were used, ClO2 consumption to bleach the pulp to 87% was lowered by 15.4% and 42.3%, respectively. As high as a 61.5% reduction in ClO2 consumption in its bleaching could be obtained using 0.66% as A.O. on pulp and change of time of OD. This result allows for a significant decrease in the chlorine passing to the filtrates from washing the pulp after the D0 and E stages to the pulp mill wastewater treatment plant.

ENHANCED SELECTIVITY OF OXYGEN DELIGNIFICATION BY CHERRY AND GUAR GUM ADDITIVES

Natural polysaccharide-based gums produced by plants in response to biotic or abiotic factors are used in various industries due to their biodegradability, renewability, biocompatibility, and non-toxic properties. This study examined the use of these gums in a new application, such as adding them to the delignification liquor to decrease the negative effects of radicals formed during the oxygen delignification of stone pine kraft pulps. For this purpose, the effects of sweet cherry gum, both with and without hydrogen peroxide reinforcement, and guar gum on oxygen delignification were examined in this study. The addition of both gums, up to a certain usage level, increased the selectivity of the reaction and protected the viscosity from oxidative damage, while causing only a limited reduction in the kappa number during the delignification process. However, it was determined that cherry gum, in hydrogen peroxide-reinforced oxygen delignification, showed no effect on selectivity, but increased pulp strength properties and better bleached pulp could be produced.

Delignification, yield, defibreability, and brightness of pine wood (Pinus sylvestris) pulped using the alkaline sulphite method with the addition of DDA and ethylene glycol

Sodium sulfite (Na2SO3) is known as a selective chemical agent for wood delignification. In this work, Scots pine (Pinus sylvestris) wood was pulped using alkaline sulfite (AS) with the addition of 1,4-dihydro-9,10-dihydroxy anthracene (DDA) [called also soluble anthraquinone (SAQ)] and ethylene glycol (G). The studies showed the possibility of obtaining Kappa number (KN) 24 to 26 alkaline sulphite-DDA pine pulps with total and screened yields higher by 3.4 to 3.9% and 1.4 to 2.6%, respectively, than in the case of kraft pulping. The AS-SAQ pulping process was also characterized by much higher brightness of pulps but worse defibreability of wood than the kraft process. Increasing the amount of Na2SO3 dosed to the wood from 25% to 30-35% (based on wood) and adding G to the cooking liquor increased the delignification of pine wood in the AS-SAQ method to Kappa number of 17 to 20 units (without G) and approximately 14.5 units (with G). Such a modification had a positive effect on the defibreability of wood after pulping and the brightness of pulps but a negative effect on the screened yield of AS-SAQ and AS-SAQG pulps.

The Effects of Autohydrolysis Pretreatment on the Properties of OPT Pulps for the Production of Dissolving Pulp

This preliminary study investigated an environmentally friendly method for fabricating cellulose-rich dissolving pulp from Oil Palm (<i>Elaeis guineensis</i>) 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.

Effects of different soda loss measurement techniques on brownstock quality

The efficiency of the kraft recovery plant, bleaching process, and paper machine are affected when black liquor carryover from the brownstock washers is not controlled well. Measuring soda loss within a mill can vary from using conductivity, either in-situ or with a lab sample of black liquor filtrate squeezed from the last stage washer, to measuring absolute sodium content with a lab sodium specific ion probe or spectrophotometer. While measuring conductivity has value in tracking trends in black liquor losses, it is not an acceptable method in reporting losses in absolute units, typically in lb/ton of pulp. This is further complicated when trying to benchmark soda loss performance across a fleet of mills with multiple washer lines. Not only do the testing methods vary, but the amount of bound soda on high kappa pulps can be significant. This variability creates inconsistent results, and studies are needed to understand the effect of different testing methods on the pulp quality. In this study, soda loss is expressed as sodium sulfate (Na2SO4). Four different methods to measure soda content in pulp off commercial brownstock washers were studied: full digestion (FD), washing soaking overnight and washing (WSW), soaking in boiling water and stirring 10-min (SW-10), and squeeze-no wash (Sq). Total, washable, and bound sodium sulfate calculations were determined for each soda content measuring technique using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results showed bound and washable sodium sulfate amounts significantly depend on which soda measurement technique was used. In addition, the soda results were correlated with the pulp kappa numbers. As the kappa number increases, bound soda increases, regardless of the soda measurement method used. Impacts of high sodium sulfate in brownstock are also discussed.

A feasibility study of oil palm empty fruit bunch pulp as a substitution for radiata pine pulp for autoclave fibre cement composite production

The main objective of this study was to investigate the feasibility of using unbleached pulp from oil palm empty fruit bunches, produced via the Ethanolamine pulping process, to replace Radiata Pine pulp in autoclave fibre cement composite (AFCC) manufacturing. The Ethanolamine pulping process was chosen for its silica retention capability on empty fruit bunch surfaces. The research involves three key phases: an initial characterization of RPP and EFBP properties, including kappa numbers and pulp aspect ratios; subsequent AFCC production with varying RPP content levels (0%–13%) and different cement-to-silica (C/S) ratios (0.2–1.0); and the introduction of EFBP as a partial or complete substitute for RPP at a fixed C/S ratio. Results reveal RPP excels in fibre quality attributes like length, coarseness, fineness, width, and wet/dry zero span, while EFBP offers advantages in fibre count and macro fibrillation index. X-ray diffraction confirms silica presence on EFBP. The highest modulus of rupture (MOR), at 15.5 MPa, is achieved with 9% RPP and a C/S ratio of 1.0. Subsequent analysis, with 1% EFBP interval substitutions to total 13% pulp content, yields the highest MOR values under dry (16.7 MPa) and wet (9.9 MPa) conditions using recipes with 6% RPP and 3% EFBP. XRD confirms the presence of silica on EFBP, forming a crystalline flake layer post-autoclaving. Thus, EFBP proves suitable as a partial AFCC substitute.

Influences of 2-ethylanthraquinone on lignin degradation in alkaline cooking of Eucalyptus pellita wood

The impact of 2-ethylanthraquinone (2-EAQ) on alkaline cooking of Eucalyptus pellita wood was examined by analyzing pulp yield, kappa number, the structure and weight-averaged molecular weight (Mw) of dissolved lignin in black liquor and residual lignin in pulp (RL). During soda cooking under 23% of active alkaline (AA) condition, adding 0.06% 2-EAQ reduced the kappa number by 12 points compared to cooking without it. The addition of 0.06% 2-EAQ to kraft cooking increased pulp yield by about 4% at about 19 of kappa number compared to the no addition. The analysis of lignin structure by using semiquantitative heteronuclear single quantum correlation nuclear magnetic resonance (HSQC NMR) showed that the addition of 2-EAQ promoted β-ether cleavage during alkaline cooking and reduced peeling reaction of polysaccharides and prevention of the elimination of γ-OH of lignin to form enol ethers and stilbenes. Overall, the addition of 2-EAQ promoted the degradation of lignin to lower molecular weight compounds, with a more pronounced effect observed in soda cooking than in kraft cooking. Under optimal conditions, the delignification efficiency and pulp yield of soda-EAQ pulping were comparable to kraft cooking.

Determining the Pulping Conditions and Properties of Unbleached Pulp from Uruguayan Pinus Taeda

Context: In Uruguay, numerous Pinus taeda plantations are at final-turn age, but they still do not have commercial destination and are exported as green-wood logs. For the development of this sector, it is necessary to strive towards a comprehensive processing of this resource. Method: This work focused on analyzing the use of Pinus taeda wood available in the country to produce brown kraft pulp with a kappa number of 80, which can be used to make packaging paper. As raw materials, we employed by-products from the mechanical wood-transformation industry (wood chips and thinning wood) and final-turn wood. Pulping tests were carried out, varying the alkali charge and the H-factor while aiming for a kappa number of 80. The viscosity, pulping, and rejection yield were measured in the pulps, and the pH and residual alkali content were evaluated in black liquor. Results: Based on the results, the best pulping conditions were an active alkali charge of 14% (Na2O) and an H-factor of 1260 for sawmill chips and thinning wood, as well as an active alkali charge of 14% (Na2O) and an H-factor of 1080 for final-turn wood. The pulp obtained with sawmill chips exhibited the most resistant fibers, and the final-turn wood pulp was the most sensitive to the refining process. Under the aforementioned conditions, the paper properties of laboratory-produced pulp are comparable with those of commercial pulp. Conclusions: This indicates that it is technologically possible to produce brown kraft pulp from Uruguayan Pinus taeda wood, with adequate quality to produce packaging paper

Strategies for multivariate characterization and classification of pulps and papers by near-infrared spectroscopy

BackgroundMultivariate calibration by Partial Least Squares (PLS) on near-infrared data has been applied successfully in several industrial sectors, including pulp and paper. The creation of multivariate calibration models relies on a set of well-characterised samples that cover the range of the intended application. However, sample sets that originate from an industrial process often show an uneven distribution of reference values. This can be addressed by curation of the reference data and the methodology for multivariate calibration. It needs to be better understood, how these approaches affect the quality and scope of the final model. ResultsWe describe the effect of log10 transformation of the reference values, regular PLS, robust PLS, the newly introduced bin PLS, and their combinations to select more evenly distributed reference values for the quantification of five pulp characteristics (kappa number, R18, R10, cuen viscosity, and brightness; 200 samples) by near-infrared spectroscopy. The quality of the models was assessed by root mean squared error of prediction, calibration range, and coverage of sample types. The best models yielded uncertainty levels equivalent to that of the reference measurement. The optimal approach depended on the investigated reference value. SignificanceRobust PLS commonly gives the model with the lowest error, but this usually comes at the cost of a notably reduced calibration range. The other approaches rarely impacted the calibration range. None of them stood out as superior; their performance depended on the calibrated parameter. It is therefore worthwhile to investigate various calibration options to obtain a model that matches the requirements of the application without compromising calibration range and sample coverage.

Recycling of printed Xerographic paper using Aspergillus assiutensis enzyme cocktail: an integrated approach to sustainable development.

To overcome the human and animal survivability risk, sustainable development is the only option on earth that can be achieved through the maximum use of renewable environmental resources. Recycling of waste paper is an emerging waste management approach to conserve natural resources. Herein, we studied enzyme-mediated process to recycle the xerographic paper by using the crude fungal extract from indigenously isolated fungi identified asAspergillus assiutensis. The fungal enzyme cocktail has been characterized for the production of multiple enzymes namely cellulase, amylase, xylanase, pectinase, and protease. All these enzymes have pH optima in the acidic range and except cellulase and all the enzymes are stable from 10 to 80C. In the zymogram analysis, pectinase, xylanase, amylase, and cellulase were detected at 68kDa, ~ 54kDa, 38kDa, and 30kDa, respectively. Also, the presence of protease was confirmed by the clear zone at 68, 31, and 16kDa. A 26% decrease in the kappa number and reduction in Hex A of the pulp was observed on the treatment of the pulp with enzyme as compared to the control pulp without any treatment. The physical and chemical properties of the pulp were also improved by enzyme-mediated pulping as compared to the control The physiochemical parameter of the effluent like TDS was reduced (397ppm) significantly in comparison to chemical deinking process and it was within the permissible limit. BOD and alkalinity were reduced when the enzymes and chemical dosage were used in combination. These results indicate that chemi-enzymatic deinking is most promising to reduce or remove the pollution parameters including ink and this approach can be used in the paper and pulp industry for sustainable development.

Understanding polyamidoamine epichlorohydrin (PAAE) retention in paper

Polyamidoamine epichlorohydrin (PAAE) is a permanent wet strength resin used in papermaking. When applied to paperboard, some amount of resin is retained in the sheet, and some is lost to the white water. The papermaker usually knows the amount of PAAE charged to the pulp but has no idea how much chemical is retained in the sheet. In addition, the influence of PAAE dosage, freeness, zeta potential, and pulp kappa number variability on PAAE retention is not well understood. Factorial design experiments using unbleached and bleached softwood (loblolly pine) kraft pulps were conducted to understand the factors that affect PAAE retention. The results revealed that PAAE retention, wet tear index, and tensile index not only depended on the PAAE charged of the pulp but also depended significantly on the pulp freeness. In lieu of freeness, zeta potential data can be used to predict PAAE retention. In addition, at similar freeness, bleached pulp has the highest retention of PAAE compared to low and high kappa unbleached kraft pulps. The results also suggest that lignin may have potential as a wet strength agent.

Alkaline Pulping of Red Meranti (Shorea selanica Blume)

The suitability for papermaking of red meranti (Shorea selanica Blume) wood for three alkaline pulping processes i.e soda, soda-anthraquinone (AQ), and kraft was studied. The fiber morphology and chemical properties were also examined. Cooks were made for 20% (as Na2O) activate alkali. The resulting pulp and paper properties were investigated. The basic density of red meranti was 0.42 g/cm3 and can be classified to be of medium density. The fibre proportion (67.14%) and fibre length (1.07 mm) of red meranti in this study were within the range of tropical hardwoods. The derived values for Runkel ratio, slender ratio, and flexibility coefficient were 0.54, 54.93, and 0.62, respectively. Furthermore, total extractives, lignin, and cellulose contents as well as solubility in 1% NaOH were 5.17%, 31.05%, 45.20%, and 26.02%, respectively. The alkaline pulps showed low kappa number (16~22) and reject level (0.5~1.5%) with the best results for screened yield (47.41%) being achieved in soda pulping. With regard to strength and optical properties of the paper hand-sheets, soda-AQ pulping showed the highest value in burst index (2.36 KPa m2/g), tear index (8.47 + 1.13 mNm2/g), and brightness (19.81%), whereas kraft pulping gave the best result in tensile index (28.39 Nm/g). The comparatively low values of yield and strength properties in kraft pulping might be due to overcooking in this experiment.

Pulp and Paper Characteristics of Five Lesser-known Species in Kalimantan: Effects of Re-beating

Five lesser-known species from natural forests in Central Kalimantan, viz., cempaka (Michelia champaca Linn), mentawa (Artocarpus rigidus Blume), menjalin (Xanthophyllum excelsum Miq.), kempili (Lithocarpus elegans (Blume) Hatus. Ex Soepadmo), and sempori (Dillenia sp.) were evaluated in the laboratory for their specific gravity, fiber morphology, pulping and papermaking properties. In addition, their properties after three-phase beating were also evaluated from a recycled paper point of view. The specific gravity and fiber length range were 0.58~0.68 and 1239~2479 μm, respectively. The highest value in specific gravity was observed in menjalin wood, while the longest fiber was observed in sempori. Kraft pulping with 14% active alkali (as Na2O), 23% sulfidity, 2 h at the maximum temperature showed that the highest screened yield was determined in cempaka wood (44.29%) with a kappa number of 17.6. The freeness ranges of unbeaten pulp were 675~780m mL CSF. The freeness ranges of 1st, 2nd, and 3rd beating were 539~630 mL, 235~275 mL, and 220~230 mL CSF, respectively. The 1st beating exhibited the best mechanical properties. Among the species, cempaka, kempili, and mentawa showed comparatively high tensile (57~60 Nm/g) and burst index (2.6~3.4 KPa m2/g), whereas the highest value for tear index (5.02 mNm2/g) was observed in sempori. A considerable decrease in fiber length, slenderness ratio, and mechanical properties of the paper was observed with an increased beating number. These findings suggest that cutting the fibers or decreasing the slenderness ratio was the main factor causing the strength to decrease.

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.

Utilization of Xylanase Enzymes Derived from Cassava in the Eco-Friendly Biobleaching of Pulp

<p align="center">The demand for paper has been increasing over time, leading to the pulp and paper industry becoming one of the largest contributors to global carbon emissions due to the chlorine-based bleaching process, particularly in Indonesia. An alternative to minimize chlorine usage involves using xylanase enzymes as part of the bleaching sequence. Xylanase can be produced from agricultural waste, including cassava residue, which contains a significant concentration of xylanase, approximately 21.3%. However, it still needs to be utilized in Indonesia. Therefore, this study aims to explore the production of xylanase enzymes from cassava residue and assess its effectiveness in the biobleaching process of pulp. The research methodology includes the production phase of xylanase enzymes by <em>Aspergillus niger</em>, chelating, bleaching sequence, bleaching, kappa number, and chemical saving assay. In the production of xylanase, the study determined that xylanase exhibits optimal activity under specific conditions, notably at a pH of 6 and a temperature of 60°C. Under these parameters, the enzymatic activity reached a level of 0.4986 U/mg protein. During the bleaching sequence, xylanase was used with doses of 0.3, 0.5, 0.7, 0.8, and 1 L/T pulp at 40, 45, 50, 55, 60, 65, and 70°C for 60 minutes. Following this process, bleaching was conducted at 65°C for 70 minutes, extraction at 80°C for 90 minutes, and a second bleaching phase. Subsequently, a kappa number test was performed, revealing the best kappa value at 60°C with a xylanase dose of 0.5 L/T pulp, reducing from an initial kappa number of 9 to 4.04. Additionally, under these conditions and dosage, xylanase enzymes could save approximately 23.67% in chlorine usage</p>