The enhanced selectivity of oxygen delignification of kraft pine wood pulps: The effects of pentosane-based cherry and guar gum additions

The enhanced selectivity of oxygen delignification of kraft pine wood pulps: The effects of pentosane-based cherry and guar gum additions | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The enhanced selectivity of oxygen delignification of kraft pine wood pulps: The effects of pentosane-based cherry and guar gum additions Ayşegül İskefyeli, Hüseyin Kırcı, Evren Ersoy Kalyoncu, Emir Erişir This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3882713/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The objective of this study was to decrease the adverse effects of radicals created in the reaction medium by adding cherry gum or guar gum, which are sugar-based polymers, into the oxygen delignification (OD) solution used in the bleaching process of pine wood pulp produced by the kraft process. In order to enhance the dissolution of lignin, peroxide was introduced into the oxygen delignification solution, resulting in the formation of a more intensive oxidative environment. The impact of each gum addition on cellulose and hemicelluloses during oxidation processes was assessed by determining pulp viscosity, kappa number, and yield values. The addition of 2% cherry gum to the OD pulp resulted in a 2.1% increase in the removal of residual lignin and a 1.9% increase in viscosity compared to the pulp without cherry gum. Similar results were also achieved in the examination of OD pulps reinforced with guar gum. The study revealed that using cherry gum and peroxide-reinforced OD pulps resulted in the lightest-colored pulps. It was observed that additions of both gums increased the strength of the pulp except for the tearing index. Kraft pulp Oxygen delignification Cherry gum Polysaccharide stabilization Environmentally friendly bleaching Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Oxygen delignification (OD) is a lignin removal process that is known for its lower effect on the environment and dependence on chemicals. The primary application of the process is the extraction of lignin from Kraft wood pulp. Additionally, it has the potential to be utilised for Sulfite wood pulps, secondary fibers (Koç et al. 2017 ), and annual plants (Hedjazi et al. 2009 ; Cao et al. 2013 ). In the early 1980s, the daily production of OD-treated pulp was about 10,000 tones (Bajpai, 2005 ; Sixta et al. 2006 ), but it became over 300,000 tones by 2010 (Valchev, 2013 ). Nevertheless, the disadvantages of the process, such as the expensive installation costs, the extra load on plant recovery systems, and the reduction in selectivity during prolonged stages, are well known and need a thorough assessment of its overall feasibility. When the rate of delignification reaches 50% and its duration is extended, the efficiency and selectivity of OD decrease Akim et al. ( 2001 ). Consequently, during extended OD stages, there is a challenge between two reactions: degradation of carbohydrates and delignification. Pretreatments (Danielewicz, 2023 ), reinforcement (Peşman et al. 2010 ), two-stage applications (van Heiningen et al. 2018 ), catalysis (Suchy and Argyropoulos, 2002 ) and selectivity-enhancing additives (Gümüşkaya et al., 2011 ) have been extensively studied to understand their impact on the selectivity, efficiency, and mechanisms of OD process. Although modifications for OD process offer advantages such as limiting environmental pollution and minimizing chemical usage, they also normally lead to additional challenges and expenses. The addition of hydrogen peroxide to OD process provides significant advantages. Previous research revealed that pulps reacted with oxygen delignification reinforced by hydrogen peroxide exhibit better physical strength characteristics and a reduced kappa number in comparison to simple oxygen-delignified pulps (Parthasarathy et al., 1990). For the following reasons, hydrogen peroxide is the solvent preferred in oxygen delignification: to enhance the brightness of the pulp and the removal of lignin; to reduce chemical consumption; and to optimize the chemical selectivity during the process (Van Lierop et al., 1994 ). For these purposes, hydrogen peroxide may offer up to 10% extra delignification when added to a single-stage OD medium at a concentration of 1% (Gullichsen and Fogelholm, 1999 ). However, the breakdown of polysaccharides accelerates as the peroxide ratio rises. Many studies show that the breakdown of cellulose may be traced back to highly reactive hydroxyl radicals that are produced in the reaction media and responsible for the degradation reactions. A significant constraint arises from carbohydrate degradation caused by free radicals during extended oxygen delignification, as highlighted by Esteves et al. ( 2020 ). Hydroxyl radicals are generated after the formation of hydrogen peroxide ion, which originated from the reduction of phenolic lignin units and transition metal ions catalyze the production of these radicals by the Fenton mechanism (Van Heiningen and Violette, 2003 ). In practice, acid washing, which is a pre-treatment, or the addition of magnesium sulphate, which reduces the catalytic impact of these ions, is used to limit the breakdown of cellulose by harmful radicals during OD. These procedures aim to chelate the pulp or eliminate transition metal ions, respectively. In addition, laboratory-scale studies involving the use of substances with radical-scavenging characteristics were conducted. Partially successful additives such as radical-scavenging are methanol (Hu et al., 2015 ), ethylene glycol (Solinas and Proust, 1997 ), and sodium gluconate (Kang et al., 1998 ). However, the overconsumption of the additives for these methods limited their industrial application. As these additives are easily soluble in water, they can be uniformly distributed in the OD reaction medium. The reaction of alkali and oxygen between all components of the fibers and residual lignin generates damaging radicals. The rapid consumption of these radicals can be attributed to their increased reactivity, while their diffusion within the solution occurs at a notably accelerated rate. As a result, these radicals generally do not interact with molecules in the solid phase. Based on this knowledge, it was hypothesized that low ratios of radical-scavenging agents potentially control oxygen radicals formed in the environment. It was also hypothesized that if radical-neutralizing additives can be widely dispersed on the cellulosic surface, they will create a barrier to protect the cellulose. It is also known that pulps with higher hemicelullose content may undergo more selective OD process (Zou et al., 2000 ). The molecular structure of polymers derived from galactoglucomannan, specifically guar gum, exhibits similarities to the structure of hemicellulose that exists in wood. Van Heiningen and Violette ( 2003 ), studied the effect of adding guar gum to the OD solution on selectivity, obtaining pulp with a higher viscosity but the same kappa number. Gümüşkaya et al. ( 2011 ) applied plum gum to stabilize polysaccharides and sodium perborate as an additional delignification additive in their study. They concluded that the addition of plum gum increased viscosity. During the evaluation of the relevant literature, no prior investigations were found that applied cherry gum for OD. This study is designed to evaluate the individual effects of cherry and guar gums on the OD process, as well as the response of the gums to introduce hydrogen peroxide into the OD process. Kappa number and viscosity were measured for each delignified pulp. Hand sheets were further manufactured to assess the impact of gums on the mechanical characteristics of the pulps. The properties of the sheets such as bursting, tearing, break length, and opacity were also examined. 2. Experimental 2.1. Raw Materials Pine (Pinus pinea L.) wood was used for pulping. After the knots and other defects were eliminated, the log was cut into discs (2–3 cm disc thickness) and then the discs were cut into pieces (2–3 cm wide) for the preparation of the chips. Using hand tools, the wooden pieces were chipped to be 2–4 mm of the chip thickness. The cherry gum derived from Prunus avium was collected in the month of April. The collected balsam was carefully preserved in controlled environments to maintain its pale color and prevent excessive oxidation. It was transported to the laboratory, mixed with a 1/10 ratio of distilled water, and blended using a shaker. The gum solution was purified by passing it through a metal sieve with a 100-mesh aperture to remove contaminants. The guar was provided in the form of powder and was dissolved in distilled water (1/10 ratio) before to usage. All the chemicals were purchased and used without any purification. 2.2. Pulping Kraft method was preferred to produce bleachable wood pulp. The active alkali ratio was 18%, the sulfide ratio was 25%, the temperature was 170°C, and the solution-to-chip ratio was kept at 4:1. The pulping time was 90 min. The cooking process was conducted in a laboratory-type rotary reactor with a 15-litre capacity, resistance to 25kg/cm 2 pressure, automated temperature control, electrical heating, and the ability to rotate twice per minute. Manual filling and discharging of the reactor were performed. The obtained pulps were mixed and stored in polyethylene bags and kept isolated from external factors. The major results for pine wood pulp produced by the kraft pulping process are as follows: viscosity (SCAN-CM 15:88 standard) of 859.40 cm 3 .gr − 1 , kappa number (TAPPI T 236 om-99) of 32.1, and screened pulp yield of 46.8%. 2.3. Oxygen Delignification Optimization studies were conducted to determine the optimal conditions for the reel delignification process, namely the OD, ODC, ODC + P, and ODG series. The experiments were conducted in the same reactor utilized for pulping and were manually filled and discharged. For all delignification setup, the conditions are the same: the temperature: 90 ºC, O2 pressure (bar): 7, the time (min): 60, MgSO 4 amount (%): 1, and the pulp concentration (%): 12. 100 g of dry pulp was used for each one. Oxygen was supplied to the reactor through the pressure relief valve. The pH of the black liquor collected from the reactor was measured after delignification. The delignified pulp was rinsed with plenty of tap water over a 150-mesh screen until the black solution was eliminated. The washed pulp was manually squeezed to ensure equal moisture distribution, and each bleached pulp was put in its plastic bag. The pulps were kept closed for 24 hours to equalize the humidity. Table 1 displays the symbolic representation of the constant and variable parameters included in the experimental systems of the OD and its variations used in this study. Table 1 Experimental design and symbolization of OD and its modifications Process* Process Conditions Symbolic representation ODn Series NaOH ratio: 1,2,3,4,5% OD1 OD2 OD3 OD4 OD5 ODCn Series NaOH ratio: 3% Cherry gum: 1,2,3,4,5% ODC1 ODC2 ODC3 ODC4 ODC5 ODCn + P Series NaOH ratio: 3% Cherry gum: 2% H 2 O 2 addition: 0.5,1,2,3,4% ODC1 + P ODC2 + P ODC3 + P ODC4 + P ODC5 + P ODGn Series NaOH ratio: 3% Guar gum: 1,2,3,4,5% ODG1 ODG2 ODG3 ODG4 ODG5 * ODn : Oxygen delignification without any reinforcements; ODCn : Cherry gum reinforced oxygen delignification; ODCn+P : Cherry gum reinforced oxygen delignification and ODGn : Guar gum reinforced oxygen delignification 2.4. Determination of Pulp Properties The following methods were employed to investigate the impact of the factors utilized in delignification on the yield, kappa number, viscosity, and mechanical qualities of the pulps. 2.4.1. Yield calculations The following equations are utilized for yield calculations of pulping and delignification processes: Screened Yield of Pulping (%) = A.B − 1 (1) Total Yield of Pulping (%) = C.B − 1 (2) Rejected Yield of Pulping (%) = (C – A). B − 1 (3) Process Yield of Delignification (%) = D.E − 1 (4) Where A is the weight of the dry pulp passing through the screen after pulping process (output) (g); B is the weight of the dry chips used in the pulping process (output) (g); C is the weight of total pulp from the reactor after pulping process (input) (g); D is the weight of the dried pulp obtained after oxygen delignification (output) (g) and E is the weight of the dried pulp obtained before oxygen delignification (input) (g). 2.4.2. Kappa number The Kappa number was determined twice for each pulp using the TAPPI T 236 om-99 standard test method. Under special conditions, it is the quantity of 0.1N KMnO 4 solution consumed by 1 g of fully dry pulp in ml. The Klason lignin remaining in the pulp as a percentage is calculated by multiplying the kappa number of the kraft pulp derived from pine wood by 0.15. For this reason, the kappa number is an important factor that should be taken into account in determining the degree of bleaching, determining the amount of lignin-free yield and calculating the number of chemicals to be used in bleaching. 2.4.3. Viscosity of Pulp The viscosity value, which is related to the degree of polymerization (DP) of the cellulose, is an important factor that indirectly affects the resistance properties of the pulp. The strength values related to the tearing and stretching of the paper, in particular, increase together with the increase in viscosity. Viscosity determination was conducted by SCAN-CM 15:88 standard. After the pulp was dissolved in 0.5M copperethylenediamine (CED) solution, its relative viscosity was found using a pipette-type viscometer and then this value was converted to actual viscosity in cm 3 .gr –1 from the table arranged according to Martin's formula. The intrinsic viscosity (η) and the degree of polymerization (DP) of cellulose in the pulp have the following relationship: DP 0.905 =0.75 × η (5) The viscosity measurement was conducted twice for each pulp sample, and the average result was presented. 2.5. Preparation of paper sheets and mechanical characterization For each pulp sample after delignification, hand sheets of about 60 g/m 2 were prepared on a Rapid Köthen Sheet Making Machine according to TAPPI T 205 sp-12. Before papermaking, the pulps were initially exposed to a 2-stage beating procedure (TAPPI T 200 om-89 standard) in the Valey type beater at periods of 9 and 12 minutes. The Schopper-Riegler Freeness Tester was used to determine and the degree of freeness according to the SCAN-C20:65 standard. Unbeaten and beaten pulp samples were used for the production of the test sheets. After recording the results from each of the physical tests performed on the produced test sheets individually in terms of the SR° degree, the values corresponding to 50 SR° were computed one by one using interpolation. After the time for conditioning (TAPPI T 402 om-88 standard), the test sheets were performed to the following tests. Preparing of the paper samples to tests: TAPPI T 220 om-88 standard, Grammage: TAPPI T 410 om-88 standard, Thickness: TAPPI T 411 om-89 standard, Opacity: TAPPI 425 om-91 standard, Brightness: TAPPI T 452 om-88 standard, Burst index: TAPPI T 403 om-91 standard, Tearing index: TAPPI T 414 om-88 standard, The breaking length: TAPPI T 494 om-88, 2.6. Statistical Analysis (One-way ANOVA) The data was subjected to statistical analysis using the One-way analysis of variance (ANOVA) method, utilising IBM SPSS version 11 software. If the simple analysis of variance indicated a statistically significant difference among the groups, the Newman-Keuls test was employed. 3. Results and Discussion The oxygen delignification process applied to Kraft pine (Pinus pinea) wood pulp, which exhibited a kappa value of 32.1, intrinsic viscosity of 859.40 cm 3 .gr − 1 , and a yield of 46.8% based on oven dry wood. 3.1. Evaluation of alkali amount optimization results Figure 1 depicts a graph of viscosity and yield changes based on pulp kappa number to understand the selectivity of delignification. As shown in the figure, the yield of delignification decreases linearly with increasing alkali concentration. Previous studies about OD indicates that the alkali charge in delignification is the primary factor influencing pulp qualities and plays a crucial role in determining the pH level of the environment (Sixta et al., 2006 ). Kappa number loss due to alkali charge increase and viscosity loss due to polysaccharide degradation verified the yield decline in pulp with the OD procedure. It was attributed to the removal of additional wood components from the pulp by the more severe reaction environment that occurred as the alkaline charge increased. Similarly, Zhang et al. ( 2023 ) found that as the cooking conditions for soda-oxygen delignification procedures were severer, the pulp's whiteness increased, and the Kappa number declined. The studies conducted by Jafari et al. ( 2015 ) and Li et al. ( 2022 ) developed the models that estimate changes in kappa number for different alkaline charge. The rate of delignification and the remaining lignin content in the pulp was calculated by them and they observed that their models correlated with the experimental delignification rate and concluded that increasing the alkali ratio resulted in greater delignification values. In the studies carried out under laboratory conditions, it was stated that the reaction intensified by increasing the alkali ratio and more lignin could be removed from the pulp. However, under harsh reaction conditions, cellulose molecules are oxidized, split, and dispersed in solution as small molecules, in addition to lignin (Suess, 2010 ). The data showed that the rate of yield loss increased significantly when the alkaline ratio exceeded 3%. Liebergott et al. ( 1985 ) found that increasing the alkali ratio during oxygen delignification (OD) led to higher lignin removal and cellulose degradation, despite constant pulp concentration and period of time. In another study, it was underlined that the reaction on lignin and polysaccharides was accelerated due to the increase in pH of the reaction medium as the alkali ratio increased. In addition, it was stated that the selectivity of the reaction decreases in OD performed with a high alkali ratio, resulting in considerable polymerization degree losses of cellulose due to attacks on the carbohydrate fraction (Gullichsen and Fogelholm, 1999 ). 3.2. Evaluation of reinforcements of OD pulps 3.2.1. The effects on chemical properties of pulps The effect of wood gum, a water-soluble hemicellulosic material with a low degree of polymerization, on selectivity during OD was studied in this work. Figure 2 shows the data on the characteristics of the pulp produced by adding gum to the OD solution. It was found that there was no notable difference among the kappa value up to 3% gum addition when comparing OD3 to both gum additions with the same alkaline amount. However, the kappa number increased when the gum addition exceeded 3%. There may be two causes for this phenomenon. Firstly, the reaction selectivity is enhanced, particularly in terms of the increased retention of hemicelluloses inside the pulp. Due to the increased quantity of hemicellulose, which acts as an intermediary component between cellulose and lignin, a greater amount of lignin was retained in the pulp. The effect shown here is about twice as pronounced for cherry gum compared to guar gum. Previous studies (Van Heiningen and Violette, 2003 and Peşman et al. 2010 ) have indicated that gums containing hemicellulosic structures, but with a lower level of polymerization, enhanced selectivity by exhibiting radical-scavenging activity in the oxygen delignification process. Secondly, the presence of an excessive quantity of hemicellulosic gum in the OD solution prevents diffusion of the solution to the mini-spaces (pores) on the fibre surface, hence limiting oxygen delignification (Van Heiningen and Violette, 2003 ; Peşman et al., 2010 müşkaya et al., 2011 ). In this study, cherry gum was added to the oxygen delignification medium primarily to prevent viscosity, not to promote delignification. The viscosity of the pulp increased by 1.7% until the amount of gum reached 2% for the ODC series. However, after it reached 3%, the viscosity stopped increasing and started to decrease. Furthermore, it was shown that exceeding a gum concentration of 2% had an adverse effect on the removal of lignin. In a study conducted by Van Heiningen and Violette in 2003, it was shown that the addition of guar gum, an absorbable polymer, to the oxygen delignification medium led to a linear improvement in reaction selectivity. This improvement continued until 2% guar gum was added, resulting in a viscosity improvement of around 5%. In this study, it was found that the viscosity-improving effect of cherry gum was less than that of guar gum, due to the different chemical structures. Guar gum is mostly composed of galactomannan-based hemicellulosic components, cherry gum also contains galactomannan but 65% of the structure of cherry gum is made up of pentosan-rich monomeric sugar structures, such as arabinose and xylose (Butler and Cretcher, 1931 ). Based on these results, it was hypothesized that hexosan-type hemicellulosic structures were more efficient for the radical-scavenging mechanisms. This work was also aimed to enhance delignification while preserving selectivity by combining the radical-scavenging effect of cherry gum with the more severe oxidative environment generated by peroxide. H 2 O 2 added to the cherry gum-doped oxygen delignification medium caused a significant decrease in the kappa number of the pulp. In Fig. 2 , it was also clear that when H 2 O 2 was added, the viscosity value of the pulp went down. H 2 O 2 is an effective oxidant that decolorizes and degrades the lignin structure whether used alone or in conjunction with other additives. In studies on the addition of H 2 O 2 to the OD solution, it was determined that peroxide showed a protective impact on pulp viscosity as well as a delignification-enhancing effect. This effect is primarily caused by the rise of lignin-oxidizing perhydroxyl ions and the reduction of detrimental hydroxonium ions. The OD experiments involved the addition of H 2 O 2 to a solution containing 2% cherry gum, which had previously been determined as the optimal concentration. Parthasarathy et al. (1990) and Peşman et al. ( 2010 ) reported that the addition of 0.5% hydrogen peroxide to an OD solution resulted in a 20% and 3% increase in viscosity, respectively. Nevertheless, these findings were not attainable in our investigation. However, the results of this study are noteworthy as they demonstrate that the incorporation of cherry gum and peroxide does not result in a substantial decrease in pulp viscosity. This means that an additional 11% of lignin may be eliminated while seeing a mere 3% decrease in pulp viscosity. The research conducted by Parthasarathy et al. (1990) and Peşman et al. ( 2010 ) found that the delignification rate increased by around 3–4% without any corresponding change in viscosity. The synergetic impact of cherry gum and peroxide is responsible for this outcome. As shown in Fig. 3 , the change in pulp yield caused by the addition of cherry gum was quite little. The increase in the cherry gum ratio resulted in a small increase in pulp production. It is possible to explain the increase with hemicellulose stabilization, more lignin remaining in the pulp due to the increase in kappa number, or some gum remaining in the pulp due to the use of more gum. The difficulties in absorbing and eliminating the cherry gum on the pulp during the washing step made determining the pulp yield quite difficult. The change in yield was displayed in the same figure as a consequence of the OD conducted by adding guar gum. The yield increased as the quantity of guar gum added to the OD medium increased, as shown in Fig. 3 . The result has a similar pattern to cherry gum. Therefore, as radical-scavenging additives, cherry gum and guar gum displayed a similar reaction mechanism but could be used interchangeably. Figure 4 provides a concise overview of the results obtained from the pulps produced by introducing hydrogen peroxide into the ODC2 system. Upon analysing the graph, it becomes evident that the yield decreases as the peroxide consumption rate increases. From this finding, we could conclude that both lignin and polysaccharides were degraded during delignification. The introduction of hydrogen peroxide into the ODC system increased its oxidative properties, indicating the removal of a portion of the pulp. A similar outcome was observed in a research study employing plum gum (Peşman et al., 2010 ). 3.2.2. The effects of mechanical properties of pulps A comprehensive analysis of variance was performed to evaluate the effects of different additives on the properties of oxygen delignification (OD), utilizing data from the specified five groups. The Newman-Keuls test was applied in cases when significant differences took place from a fundamental analysis of variance. The physical and optical properties that are important to OD-treated pulps were evaluated using defined methods, and the results are presented in Table 2 . Table 2 The effect of some herbal gums and hydrogen peroxide added to the solution medium in the OD process applied to unbleached pine kraft pulp on the physical and optical properties of the pulp. Sample Code Paper weight (g) Thickness (µm) Opacity (%) Brightness (%) Breaking length (km) Burst index (kPa.m 2 .gr –1 ) Tearing index (mN.m 2 .gr –1 ) Control (K) 64.83 (± 2.48) 74.93 (± 3.65) 92.76 (± 0.91) 30.04 (± 0.46) 3.63 (± 0.62) 2.89 (± 0.15) 5.95 (± 0.24) OD3 64.60 (± 1.90) 78.00 (± 2.73) 83.84 (± 0.75) 49.69 (± 0.47) 3.69 (± 0.49) 2.73 (± 0.20) 5.48 (± 0.24) ODC2 59.90 (± 5.20) 77.82 (± 5.05) 84.27 (± 1.68) 49.71 (± 0.56) 4.21 (± 0.65) 2.71 (± 0.19) 5.79 (± 0.27) ODC2 + P 65.70 (± 2.70) 79.12 (± 3.63) 80.41 (± 1.26) 54.59 (± 0.31) 4.02 (± 0.48) 2.95 (± 0.24) 5.56 (± 0.00) ODG2 67.10 (± 1.20) 81.30 (± 2.40) 85.20 (± 0.69) 48.88 (± 0.27) 4.32 (± 0.57) 2.82 (± 0.18) 4.70 (± 0.07) The study employed the accepted standard value of 50 SR° (freeness of pulp) as a reference point. Interpolation techniques were used to evaluate the basic strength and optical properties related to this level of freeness, ensuring precision in the study. The difference between the strength properties and the values obtained from the undelignified pine kraft control pulp (K) and the pulp delignified with conventional and modified oxygen delignification (OD) was statistically tested at the 5% significance level. There was a limited improvements in breaking length when oxygen delignification was applied to pine kraft pulp without any reinforcements. However, the impact progressively improved by the addition of reinforcements to the OD stage. Individually, the addition of cherry gum and guar gum contribute positively to the breaking length of kraft pine pulp from 3.63 (± 0.62) to 4.21 (± 0.65) and 4.02 (± 0.48) km, respectively. Cherry gum in combination with hydrogen peroxide shown better performance up to 4.32 (± 0.57) km. Erişir et al. ( 2015 ) found that an increase in the hemicellulose content in the pulp led to a decrease in the strength properties of the paper sheets. Indeed, similarly, Spönla et al. ( 2023 ) reported that an increase of the hemicellulose content in the fibers had an adverse impact on strength properties. The study revealed that the addition of gum during oxygen delignification improved the removal of lignin from the fibers, resulting in greater bonding ability and higher breaking resistance, due to the protection of the pulp's viscosity value. Miao et al. ( 2023 ) quoted by Jie Cai et al. (2015) reported that chemical treatment processes, particularly those consisting of NaOH aqueous solutions, can cause major lateral swelling of the fiber, leading to changes in its bonding properties and strength. The previous sections provided comprehensively description of the adverse effects of OD on fibers. The pulp of oxygen delignification with guar gum showed the lowest tear index value of 4.70 mN.m 2 .g − 1 . Conversely, among the various types of pulps, unbleached pine kraft pulp (K) exhibited the highest tearing index value of 5.95 mN.m 2 .g − 1 , as well as the greatest viscosity compared to all other pulps. The tearing index, a measure of the tensile qualities of pulp, is significantly impacted by the decrease in pulp viscosity. Brogdon and Lucia ( 2023 ) conducted a study on the relationship between Kraft pulp viscosity and paper strength. They found that there is a positive correlation between pulp viscosity and the tearing index. Another study conducted by Carvalho et. al ( 2000 ) revealed a correlation between tear index and pulp viscosity, indicating that pulps with greater viscosity exhibited a higher tear index.The statistical analysis indicated that there was no statistically significant difference between the groups at the 5% significance level. It suggests that the increase in delignification did not have an important effect on the paper's burst index. The main idea of employing OD is to reduce the remaining lignin concentration in the pulp in order to get a pulp that can be bleached. Basically, it is similar to the continuous soda-oxygen pulping process. Nevertheless, the presence of peroxide and perhydroxyl groups in the solution used for the reaction and the ability to oxidize the remaining lignin structure in the pulp, resulting in a brightening of its color, clearly indicates that this technique has a bleaching effect. According to Gullichsen and Fegelholm (1999), the optical brightening agent (OD) enhances brightness by 15–20% ISO and the extent of improvement depends on factors such as the kind of raw material, cooking technique, and the amount of residual lignin in the pulp. In this study, it was achieved an 18.4% increase in brightness using guar gum reinforced OD on kraft pulp. Additionally, a 19.7% increase was obtained using cherry gum reinforced OD, and a 24.6% increase was achieved using cherry gum and H 2 O 2 reinforcement. Similarly, Koç et al. ( 2017 ) reported that reinforced OD as compared to pure OD resulted in approximately 20% improvement in brightness value. Kappa number changes of pulps, which explain the changes in the degree of delignification in pulping, oxygen delignification, and pre-bleaching processes, are an important parameter used in the analysis of the amount of residual lignin in the pulp (Ning et al., 2019 ). According to Eiras et al. ( 2008 ), the pulp brightness is most affected by the chromophoric groups in the residual lignin. So that, the pulp of cherry gum and peroxide reinforced OD number exhibited the greatest increase in brightness, as well as the highest level of delignification. The results demonstrate the versatility of gums for oxygen delignification and their positive effect on the optical characteristics of pulp. This presents a promising and efficient option for the paper and pulp industry, which is also more ecologically sustainable. 4. Conclusions This study applied cherry and guar gums, sugar-based natural polymers, as an additive in the reaction medium to enhance the selectivity of the conventional single-stage oxygen delignification (OD) process for Kraft pine pulp. The addition of hydrogen peroxide was also tried to boost delignification while minimizing any substantial decrease in viscosity. First, bleachable pulp resulted in a pulp with a 46.8% yield, a kappa number of 32.1, and a value of 859.4 cm 3 .g − 1 . The pulp exhibited a good bleachability. The study mainly focused on evaluating the most optimal conditions for OD with and without additives. It was discovered that the optimal alkali charge for OD was 3%. An increase in the alkaline amount has decreased the delignification yield and led to a decrease in the consistency of the pulp. Under the conditions of optimum alkali charge, the application of OD produced a decrease in viscosity of just 6.1% and a removal of lignin at a rate of 54.8% for the pulp. By introducing cherry and guar gums into the reaction media under specified OD conditions, the delignification ratio increased by 2.1% and 6.2% correspondingly. This indicates that both gum affects the selectivity in the OD process. The combination of wood gum and peroxide has both increased delignification and significantly improved the brightness of the pulp. By introducing 1% hydrogen peroxide with 2% cherry gum into the OD, the process of delignification can be enhanced by 13.1%, even if there is only a minimal decrease in viscosity of 1.36%. The combined application of cherry gum and hydrogen peroxide reinforcements led to a statistically significant improvement in various strength properties, except for the tearing index. When examining the effects of different reinforcements on mechanical properties, it was observed that additions of both gums increased the strength of the pulp. The findings demonstrate that the combination of oxygen delignification and certain reinforcements can enhance the product properties in the paper and pulp industry. Moreover, the use of plant-based reinforcements, such as wood gums, improves the selectivity of the OD process. It offers significant potential for both sustainable development and high-quality products. Ultimately, by tailoring the oxygen delignification process within specific conditions and reinforcing it by suitable enhancements, it still has the potential to improve to a more effective and environmentally friendly method for the paper and pulp industry. Declarations Acknowledgments The authors express their gratitude to the Scientific and Technological Research Council of Turkey (TUBITAK), Grant Number: 110O894 for financial support. Authorship contribution statement Hüseyin KIRCI: Investigation, Conceptualization, Design, Funding Acquisition, Project Administration, Analysis, Visualization, Reviewing and Editing—First Draft of the Manuscript Ayşegül İSKEFYELİ: Data Collection, Analysis, Writing— First Draft of the Manuscript Evren ERSOY KALYONCU: Data Collection, Reviewing and Editing— First Draft of the Manuscript Emir ERİŞİR: Material Preparation, Investigation, Writing, Reviewing and Editing — First Draft of the Manuscript, Visualization Funding This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) [grant number 110O894]. Data availability Data will be made available on request. Declarations Confict of interest The authors declare no confict of interest. Ethical approval Ethics approval was not required for this research References Akim, L. G., Colodette, J. L., Argyropoulos, D. S. (2001) Factors limiting oxygen delignification of kraft pulp. Canadian Journal of Chemistry, 79(2), 201–210. DOI: https://doi.org/10.1139/v01-007 Bajpai, P., (2005) Cleaner Production Measures in Pulp and Paper Processing. In Environmentally Benign Approaches for Pulp Bleaching, Developments in Environmental Management, Elsevier, pp. 119. Brogdon, B. N., Lucia, L. A. (2023) Kraft pulp viscosity as a predictor of paper strength: Its uses and abuses. TAPPI Journal, 22(10), 631–643. Butler, C. L., Cretcher, L. H. (1931) The Composition of Cherry Gum. Journal of the American Chemical Society, 53(11), 4160–4167. DOI: https://doi.org/10.1021/ja01362a034 Cao, S., Ma, X., Luo, X., Huang, F., Huang, L., Chen, L. (2013) Effect of Hydroxyl Radical on the Selectivity of Delignification during Oxygen Delignification of Bamboo Pulp. Bioresources, 8 (2), 2657–2668. Carvalho, M. G., Ferreira, P. J., Figueiredo, M. M. (2000) Cellulose depolymerisation and paper properties in E. globulus kraft pulps. Cellulose, 7, 359–368. DOI: https://doi.org/10.1023/A:1009293924205 Danielewicz, D. (2023) The effect of treating pine regular kraft pulp with peracetic acid before O2-delignification on the consumption of ClO2 in D0ED1 bleaching. BioResources, 18(2), 2746. DOI: https://doi.org/10.15376/biores.18.2.2746-2755 Eiras, K. M. M., Colodette, J. L., Silva, V. L. and Barbosa, L. C. A. (2008) New insights on brightness stability of eucalyptus kraft pulp. Nordic Pulp & Paper Research Journal, 23(1), 102–107. https://doi.org/10.3183/npprj-2008-23-01-p102-107 Erişir, E., Gümüşkaya, E., Kirci, H., Misir, N. (2015) Alkaline sulphite pulping of Caucasian spruce (Picea orientalis L.) chips with additions of NaBH4 and ethanol. Drewno: prace naukowe, doniesienia, komunikaty, 58(194), 89–102. DOI: https://doi.org/10.12841/wood.1644-3985.067.07 Esteves C.V., Brännvall, E., Östlund, S. Sevastyanova, O. (2020) Evaluating the potential to modify pulp and paper properties through oxygen delignifcation. ACS Omega, 5:13703–13711. DOI: https://doi.org/10.1021/acsomega.0c008 69 Gullichsen, J., Fogelholm, C.J. (1999) Chemical Pulping. In Papermaking Science and Technology Series, 6A, (pp. 693), Tappi Press, USA. Gümüşkaya, E., Peşman, E., Kirci, H. Uçar, M. B. (2011) Influence of plum gum and sodium perborate addition on spruce kraft pulp properties during oxygen delignification. Wood Science and Technology, 45(3), 573–582. DOI: https://doi.org/10.1007/s00226-010-0367-x Hedjazi S., Kordsachia O., Patt R., Latibari A.J. Tschirner U. (2009) Alkaline sulfite- -anthraquinone (AS/AQ) pulping of wheat straw and totally chlorine free (TCF) bleaching of pulps. Industrial Crops and Products, 29, 27–36. DOI: https://doi.org/10.1016/j.indcrop.2008.03.013 Hu, H. C., Chai, X. S., Zhang, C. Y., Fu, L. M., Barnes, D., Huang, L., & Chen, L. (2015). Experimental data and kinetic models in terms of methanol formation during oxygen delignification processes of alkaline pulps. Holzforschung, 69(8), 933–942. https://doi.org/10.1515/hf-2014-0246 Jafari, V., Nieminen, K., Sixta, H., van Heiningen, A. (2015) Delignification and cellulose degradation kinetics models for high lignin content softwood Kraft pulp during flow-through oxygen delignification. Cellulose, 22, 2055–2066. DOI: https://doi.org/10.1007/s10570-015-0593-3 Kang, G. J., Ni, Y., Van Heiningen, A. R. P., McKenzie, J. (1998) Effect of Selected Chemicals in Recycled Filtrate on the Selectivity during O2 Delignification. In TAPPI Pulping Conference Proceedings Book (pp. 243–250). TAPPI PRESS. Koç, B. O., Gümüşkaya, E., Erişir, E., Peşman, E. Kirci, H. (2017) Comparison of reinforced oxygen delignification methods for oldcorrugated board (OCC) fibres. Drewno: prace naukowe, doniesienia, komunikaty, 60. DOI: https://doi.org/10.12841/wood.1644-3985.208.04 Li, J., Miao, G., He, L., Chen, K., Guan, Q., Qian, W., Zhou, H. (2022) Analyzing the delignification, carbohydrate degradation kinetics, and mechanism of wet-storage bagasse in oxygen-alkali cooking. Cellulose, 29(17), 9421–9435. DOI: https://doi.org/10.1007/s10570-022-04843-9 Liebergott, N., Van Lierop, B., Teoderescu, G., Kubes, G.J., (1985) Comparison Between Low and High Consistency Oxygen Delignification of Kraft Pulp, in: TAPPI Pulping Conference Proceedings, TAPPI Press, pp. 213–217, Atlanta. Miao, Y., Xiang, S., Wei, Y., Long, X., Qiu, J., & Miao, Y. (2023). Physical Properties of Pulp and Paper: A Comparison of Forming Procedures. Forest Products Journal, 73(2), 175–185. https://doi.org/10.13073/FPJ-D-23-00007 Ning, D., Hu, Y., Fu, C. Chen, L. Huang, H., Cao, S., Ni, Y. Huang, F. (2019) Effect of the particle size of magnesium hydroxide on the cellulose polymerization during the oxygen delignification of radiata pine kraft pulp. Cellulose 26, 6571–6581. https://doi.org/10.1007/s10570-019-02569-9 Parthasarthy, V.R., Klein, R., Sundaram, V.S.M., Jammel, H., Gratzl, J.S. (1990) Hydrogen-Peroxide-Reinforced Oxygen Delignification of Southern Pine Kraft Pulp and Short Sequence Bleaching, TAPPI Journal, 73(7), 177–185. Peşman, E., Kalyoncu, E. E. Kirci, H. (2010) Sodium perborate usage instead of hydrogen peroxide for the reinforcement of oxygen delignification. Fib. and Tex. in Eastern Europe, 18(6), 83, 106–109. Sixta, H., Süss, H.U., Potthast, A., Schwanninger, M., Krotscheck, A. W. (2006) Pulp Bleaching. In Sixta, H. (Ed.), Handbook of Pulp, Vol:1. (pp. 628–734), WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Solinas, M., Proust, A. M. (1997) U.S. Patent No. 5,609,723. Washington, DC: U.S. Patent and Trademark Office. Suchy, M., Argyropoulos, D. S. (2002) Catalysis and activation of oxygen and peroxide delignification of chemical pulps: a review. TAPPI Journal, 1(2), 1–18. DOI: https://doi.org/10.1021/bk-2001-0785.ch001 Spönla, E., Hannula, S., Kamppuri, T., Holopainen-Mantila, U., Sulaeva, I., Potthast, A., Harlin, A., Grönqvist, S., Rahikainen, J. (2023) Hemicellulose-rich paper-grade pulp as raw material for regenerated fibres in an ionic liquid-based process. Cellulose 30, 11407–11423. https://doi.org/10.1007/s10570-023-05589-8 Suess, H., (2010). Bleaching of chemical pulp. In Pulp Bleaching Today (pp. 56). Walter de Gruyter GmbH & Co. KG, Berlin/New York. DOI: https://doi.org/10.1515/9783110218244 Valchev, I. (2013). Oxygen Delignification. In Popa, V. I. (Ed.), Pulp Production and Processing: From Papermaking to High-Tech Products (pp. 76), Smithers Rapra Technology Ltd, Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK. Van Heiningen, A., Violette, S. (2003) Selectivity lmprovement During Oxygen Delignification by Adsorption. Journal of pulp and paper science, 29(2). van Heiningen, A. R., Ji, Y., Jafari, V. (2018) Recent progress on oxygen delignification of softwood kraft pulp. In Rosenau, T., Potthast, A., Hell, J. (Eds.), Cellulose science and technology: chemistry, analysis, and applications (67) John Wiley & Sons, Inc., NJ, USA. Van Lierop, B., Liebergott, N., Faubert, M. G. (1994) Using oxygen and peroxide to bleach kraft pulps. Journal of pulp and paper science, 20(7), J193. Zhang, K., Li, J., He, L., Zhou, H., Guan, Q., Chen, K., Shan, S. & Hu, T. (2023). Preparation of cellulose nano/microfibres with ultra-high aspect ratios from tobacco stem using soda-oxygen delignification and ultrasonication. Cellulose, 1–16. https://doi.org/10.1007/s10570-023-05215-7 Zou, H., Liukkonen, A., Cole, B., Genco, J., Miller, W. (2000) Influence of kraft pulping on the kinetics of oxygen delignification. TAPPI journal, 83(2). Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3882713","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":268593643,"identity":"595576a4-e131-46c9-963b-7af82ea74674","order_by":0,"name":"Ayşegül İskefyeli","email":"","orcid":"","institution":"Karadeniz Technical University","correspondingAuthor":false,"prefix":"","firstName":"Ayşegül","middleName":"","lastName":"İskefyeli","suffix":""},{"id":268593644,"identity":"9b867112-f3c1-4eac-8062-f0adb7633565","order_by":1,"name":"Hüseyin Kırcı","email":"","orcid":"","institution":"Karadeniz Technical University","correspondingAuthor":false,"prefix":"","firstName":"Hüseyin","middleName":"","lastName":"Kırcı","suffix":""},{"id":268593645,"identity":"5279bba8-98a6-4e52-bede-154e6aa53d01","order_by":2,"name":"Evren Ersoy Kalyoncu","email":"","orcid":"","institution":"Arsin Vocational School, Karadeniz Technical University","correspondingAuthor":false,"prefix":"","firstName":"Evren","middleName":"Ersoy","lastName":"Kalyoncu","suffix":""},{"id":268593646,"identity":"c8f6f9ce-6f4d-4f7d-9a76-7c3eb43bc551","order_by":3,"name":"Emir Erişir","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIiWNgGAWjYFACxgYgIcHAxsB8AMJmSCBaC1sCQssB4qzjMSBOC7/Y4bYPH/dY2PNJn/n8mXfHYQZ+9hwD5o97cGuRnJ3YPHPGM4nENr7cbdK8Zw4zSPa8MWA48Ay3FoPbic3MPAckEth4eLcx87YdZjC4kQPUgsdl9iAtfw5I2LPx8Dz+DNJiT0iLgTRQC8MBCcY2Hh4GabAtEgS0SABtYew5APQLD5uZ5Nwz6TwSZ54VHDiDRwv/7PTHDD8O1NnL9zA//vB2h7Ucf3vyxgcVeLRgAB4QQYqGUTAKRsEoGAVYAAAty07+JCqEagAAAABJRU5ErkJggg==","orcid":"","institution":"Sakarya University of Applied Sciences","correspondingAuthor":true,"prefix":"","firstName":"Emir","middleName":"","lastName":"Erişir","suffix":""}],"badges":[],"createdAt":"2024-01-20 22:15:03","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3882713/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3882713/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":50095548,"identity":"2dcf361f-bb1c-4eb8-8528-244e98c7c478","added_by":"auto","created_at":"2024-01-24 13:17:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":32166,"visible":true,"origin":"","legend":"\u003cp\u003eThe relationship of pulp viscosity and process yield with kappa number during oxygen delignification at the different alkali additions (Red: yield, Black: pulp viscosity).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-3882713/v1/d4b91b05b6b1470f50b4a011.png"},{"id":50096021,"identity":"a5faed0a-778c-4dc6-a096-f2a405834281","added_by":"auto","created_at":"2024-01-24 13:25:34","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":349807,"visible":true,"origin":"","legend":"\u003cp\u003eThe change in the kappa number of oxygen-delignified pine kraft pulp reinforced by different additives (The black line: ODCn+P; The red line: ODGn; The green line: ODCn).\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-3882713/v1/b292542edf9901b41bfbfacf.jpeg"},{"id":50095549,"identity":"ce9a1559-5a4e-4fe5-a16c-05fb5ca2e3a2","added_by":"auto","created_at":"2024-01-24 13:17:34","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":275829,"visible":true,"origin":"","legend":"\u003cp\u003eThe effects of cherry gum and guar gum addition to solution of oxygen delignification on process yield of pulps.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-3882713/v1/c5ede774f6673b5cac799b74.jpeg"},{"id":50095550,"identity":"db0e39a8-1638-4779-b866-1122324e4297","added_by":"auto","created_at":"2024-01-24 13:17:34","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":276148,"visible":true,"origin":"","legend":"\u003cp\u003eThe effects of cherry gum addition to the solution of oxygen delignification on process yield of pulps.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-3882713/v1/99a4fc5d1d0341cfe1248b58.jpeg"},{"id":50378413,"identity":"52c06f99-7d0f-4e5a-9078-e6bacef6faa9","added_by":"auto","created_at":"2024-01-30 15:56:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":618592,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3882713/v1/4c1af611-f82d-48cc-b6e3-a382b2752e09.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The enhanced selectivity of oxygen delignification of kraft pine wood pulps: The effects of pentosane-based cherry and guar gum additions","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eOxygen delignification (OD) is a lignin removal process that is known for its lower effect on the environment and dependence on chemicals. The primary application of the process is the extraction of lignin from Kraft wood pulp. Additionally, it has the potential to be utilised for Sulfite wood pulps, secondary fibers (Ko\u0026ccedil; et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), and annual plants (Hedjazi et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2009\u003c/span\u003e; Cao et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). In the early 1980s, the daily production of OD-treated pulp was about 10,000 tones (Bajpai, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Sixta et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), but it became over 300,000 tones by 2010 (Valchev, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2013\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNevertheless, the disadvantages of the process, such as the expensive installation costs, the extra load on plant recovery systems, and the reduction in selectivity during prolonged stages, are well known and need a thorough assessment of its overall feasibility. When the rate of delignification reaches 50% and its duration is extended, the efficiency and selectivity of OD decrease Akim et al. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). Consequently, during extended OD stages, there is a challenge between two reactions: degradation of carbohydrates and delignification.\u003c/p\u003e \u003cp\u003ePretreatments (Danielewicz, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), reinforcement (Peşman et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003e), two-stage applications (van Heiningen et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), catalysis (Suchy and Argyropoulos, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2002\u003c/span\u003e) and selectivity-enhancing additives (G\u0026uuml;m\u0026uuml;şkaya et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) have been extensively studied to understand their impact on the selectivity, efficiency, and mechanisms of OD process. Although modifications for OD process offer advantages such as limiting environmental pollution and minimizing chemical usage, they also normally lead to additional challenges and expenses.\u003c/p\u003e \u003cp\u003eThe addition of hydrogen peroxide to OD process provides significant advantages. Previous research revealed that pulps reacted with oxygen delignification reinforced by hydrogen peroxide exhibit better physical strength characteristics and a reduced kappa number in comparison to simple oxygen-delignified pulps (Parthasarathy et al., 1990). For the following reasons, hydrogen peroxide is the solvent preferred in oxygen delignification: to enhance the brightness of the pulp and the removal of lignin; to reduce chemical consumption; and to optimize the chemical selectivity during the process (Van Lierop et al., \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1994\u003c/span\u003e). For these purposes, hydrogen peroxide may offer up to 10% extra delignification when added to a single-stage OD medium at a concentration of 1% (Gullichsen and Fogelholm, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1999\u003c/span\u003e). However, the breakdown of polysaccharides accelerates as the peroxide ratio rises.\u003c/p\u003e \u003cp\u003eMany studies show that the breakdown of cellulose may be traced back to highly reactive hydroxyl radicals that are produced in the reaction media and responsible for the degradation reactions. A significant constraint arises from carbohydrate degradation caused by free radicals during extended oxygen delignification, as highlighted by Esteves et al. (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Hydroxyl radicals are generated after the formation of hydrogen peroxide ion, which originated from the reduction of phenolic lignin units and transition metal ions catalyze the production of these radicals by the Fenton mechanism (Van Heiningen and Violette, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2003\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn practice, acid washing, which is a pre-treatment, or the addition of magnesium sulphate, which reduces the catalytic impact of these ions, is used to limit the breakdown of cellulose by harmful radicals during OD. These procedures aim to chelate the pulp or eliminate transition metal ions, respectively. In addition, laboratory-scale studies involving the use of substances with radical-scavenging characteristics were conducted. Partially successful additives such as radical-scavenging are methanol (Hu et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), ethylene glycol (Solinas and Proust, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1997\u003c/span\u003e), and sodium gluconate (Kang et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e1998\u003c/span\u003e). However, the overconsumption of the additives for these methods limited their industrial application. As these additives are easily soluble in water, they can be uniformly distributed in the OD reaction medium.\u003c/p\u003e \u003cp\u003eThe reaction of alkali and oxygen between all components of the fibers and residual lignin generates damaging radicals. The rapid consumption of these radicals can be attributed to their increased reactivity, while their diffusion within the solution occurs at a notably accelerated rate. As a result, these radicals generally do not interact with molecules in the solid phase. Based on this knowledge, it was hypothesized that low ratios of radical-scavenging agents potentially control oxygen radicals formed in the environment. It was also hypothesized that if radical-neutralizing additives can be widely dispersed on the cellulosic surface, they will create a barrier to protect the cellulose.\u003c/p\u003e \u003cp\u003eIt is also known that pulps with higher hemicelullose content may undergo more selective OD process (Zou et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). The molecular structure of polymers derived from galactoglucomannan, specifically guar gum, exhibits similarities to the structure of hemicellulose that exists in wood. Van Heiningen and Violette (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2003\u003c/span\u003e), studied the effect of adding guar gum to the OD solution on selectivity, obtaining pulp with a higher viscosity but the same kappa number. G\u0026uuml;m\u0026uuml;şkaya et al. (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) applied plum gum to stabilize polysaccharides and sodium perborate as an additional delignification additive in their study. They concluded that the addition of plum gum increased viscosity.\u003c/p\u003e \u003cp\u003eDuring the evaluation of the relevant literature, no prior investigations were found that applied cherry gum for OD. This study is designed to evaluate the individual effects of cherry and guar gums on the OD process, as well as the response of the gums to introduce hydrogen peroxide into the OD process. Kappa number and viscosity were measured for each delignified pulp. Hand sheets were further manufactured to assess the impact of gums on the mechanical characteristics of the pulps. The properties of the sheets such as bursting, tearing, break length, and opacity were also examined.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Raw Materials\u003c/h2\u003e \u003cp\u003ePine (Pinus \u003cem\u003epinea\u003c/em\u003e L.) wood was used for pulping. After the knots and other defects were eliminated, the log was cut into discs (2\u0026ndash;3 cm disc thickness) and then the discs were cut into pieces (2\u0026ndash;3 cm wide) for the preparation of the chips. Using hand tools, the wooden pieces were chipped to be 2\u0026ndash;4 mm of the chip thickness.\u003c/p\u003e \u003cp\u003eThe cherry gum derived from \u003cem\u003ePrunus avium\u003c/em\u003e was collected in the month of April. The collected balsam was carefully preserved in controlled environments to maintain its pale color and prevent excessive oxidation. It was transported to the laboratory, mixed with a 1/10 ratio of distilled water, and blended using a shaker. The gum solution was purified by passing it through a metal sieve with a 100-mesh aperture to remove contaminants. The guar was provided in the form of powder and was dissolved in distilled water (1/10 ratio) before to usage. All the chemicals were purchased and used without any purification.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Pulping\u003c/h2\u003e \u003cp\u003eKraft method was preferred to produce bleachable wood pulp. The active alkali ratio was 18%, the sulfide ratio was 25%, the temperature was 170\u0026deg;C, and the solution-to-chip ratio was kept at 4:1. The pulping time was 90 min. The cooking process was conducted in a laboratory-type rotary reactor with a 15-litre capacity, resistance to 25kg/cm\u003csup\u003e2\u003c/sup\u003e pressure, automated temperature control, electrical heating, and the ability to rotate twice per minute. Manual filling and discharging of the reactor were performed. The obtained pulps were mixed and stored in polyethylene bags and kept isolated from external factors. The major results for pine wood pulp produced by the kraft pulping process are as follows: viscosity (SCAN-CM 15:88 standard) of 859.40 cm\u003csup\u003e3\u003c/sup\u003e.gr\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, kappa number (TAPPI T 236 om-99) of 32.1, and screened pulp yield of 46.8%.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Oxygen Delignification\u003c/h2\u003e \u003cp\u003eOptimization studies were conducted to determine the optimal conditions for the reel delignification process, namely the OD, ODC, ODC\u0026thinsp;+\u0026thinsp;P, and ODG series. The experiments were conducted in the same reactor utilized for pulping and were manually filled and discharged.\u003c/p\u003e \u003cp\u003eFor all delignification setup, the conditions are the same: the temperature: 90 \u0026ordm;C, O2 pressure (bar): 7, the time (min): 60, MgSO\u003csub\u003e4\u003c/sub\u003e amount (%): 1, and the pulp concentration (%): 12. 100 g of dry pulp was used for each one. Oxygen was supplied to the reactor through the pressure relief valve. The pH of the black liquor collected from the reactor was measured after delignification. The delignified pulp was rinsed with plenty of tap water over a 150-mesh screen until the black solution was eliminated. The washed pulp was manually squeezed to ensure equal moisture distribution, and each bleached pulp was put in its plastic bag. The pulps were kept closed for 24 hours to equalize the humidity.\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e displays the symbolic representation of the constant and variable parameters included in the experimental systems of the OD and its variations used in this study.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eExperimental design and symbolization of OD and its modifications\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProcess*\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProcess Conditions\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"5\" nameend=\"c7\" namest=\"c3\"\u003e \u003cp\u003eSymbolic representation\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eODn\u003c/p\u003e \u003cp\u003eSeries\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaOH ratio: 1,2,3,4,5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eOD1\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eOD2\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eOD3\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eOD4\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eOD5\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eODCn Series\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaOH ratio: 3%\u003c/p\u003e \u003cp\u003eCherry gum: 1,2,3,4,5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC1\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC2\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC3\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC4\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC5\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eODCn\u0026thinsp;+\u0026thinsp;P\u003c/p\u003e \u003cp\u003eSeries\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaOH ratio: 3%\u003c/p\u003e \u003cp\u003eCherry gum: 2%\u003c/p\u003e \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e addition: 0.5,1,2,3,4%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC1\u0026thinsp;+\u0026thinsp;P\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC2\u0026thinsp;+\u0026thinsp;P\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC3\u0026thinsp;+\u0026thinsp;P\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC4\u0026thinsp;+\u0026thinsp;P\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODC5\u0026thinsp;+\u0026thinsp;P\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eODGn Series\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNaOH ratio: 3%\u003c/p\u003e \u003cp\u003eGuar gum: 1,2,3,4,5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODG1\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODG2\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODG3\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODG4\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cspan type=\"SmallCaps\" class=\"SmallCaps\" name=\"Emphasis\"\u003eODG5\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e\u003csup\u003e\u003cb\u003e* ODn\u003c/b\u003e: Oxygen delignification without any reinforcements; \u003cb\u003eODCn\u003c/b\u003e: Cherry gum reinforced oxygen delignification; \u003cb\u003eODCn+P\u003c/b\u003e: Cherry gum reinforced oxygen delignification and \u003cb\u003eODGn\u003c/b\u003e: Guar gum reinforced oxygen delignification\u003c/sup\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Determination of Pulp Properties\u003c/h2\u003e \u003cp\u003eThe following methods were employed to investigate the impact of the factors utilized in delignification on the yield, kappa number, viscosity, and mechanical qualities of the pulps.\u003c/p\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.4.1. Yield calculations\u003c/h2\u003e \u003cp\u003eThe following equations are utilized for yield calculations of pulping and delignification processes:\u003c/p\u003e \u003cp\u003eScreened Yield of Pulping (%)\u0026thinsp;=\u0026thinsp;A.B\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (1)\u003c/p\u003e \u003cp\u003eTotal Yield of Pulping (%)\u0026thinsp;=\u0026thinsp;C.B\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (2)\u003c/p\u003e \u003cp\u003eRejected Yield of Pulping (%) = (C \u0026ndash; A). B\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (3)\u003c/p\u003e \u003cp\u003eProcess Yield of Delignification (%)\u0026thinsp;=\u0026thinsp;D.E\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (4)\u003c/p\u003e \u003cp\u003eWhere A is the weight of the dry pulp passing through the screen after pulping process (output) (g); B is the weight of the dry chips used in the pulping process (output) (g); C is the weight of total pulp from the reactor after pulping process (input) (g); D is the weight of the dried pulp obtained after oxygen delignification (output) (g) and E is the weight of the dried pulp obtained before oxygen delignification (input) (g).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.4.2. Kappa number\u003c/h2\u003e \u003cp\u003eThe Kappa number was determined twice for each pulp using the TAPPI T 236 om-99 standard test method. Under special conditions, it is the quantity of 0.1N KMnO\u003csub\u003e4\u003c/sub\u003e solution consumed by 1 g of fully dry pulp in ml. The Klason lignin remaining in the pulp as a percentage is calculated by multiplying the kappa number of the kraft pulp derived from pine wood by 0.15. For this reason, the kappa number is an important factor that should be taken into account in determining the degree of bleaching, determining the amount of lignin-free yield and calculating the number of chemicals to be used in bleaching.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.4.3. Viscosity of Pulp\u003c/h2\u003e \u003cp\u003eThe viscosity value, which is related to the degree of polymerization (DP) of the cellulose, is an important factor that indirectly affects the resistance properties of the pulp. The strength values related to the tearing and stretching of the paper, in particular, increase together with the increase in viscosity.\u003c/p\u003e \u003cp\u003eViscosity determination was conducted by SCAN-CM 15:88 standard. After the pulp was dissolved in 0.5M copperethylenediamine (CED) solution, its relative viscosity was found using a pipette-type viscometer and then this value was converted to actual viscosity in cm\u003csup\u003e3\u003c/sup\u003e.gr\u003csup\u003e\u0026ndash;1\u003c/sup\u003e from the table arranged according to Martin's formula. The intrinsic viscosity (η) and the degree of polymerization (DP) of cellulose in the pulp have the following relationship:\u003c/p\u003e \u003cp\u003eDP\u003csup\u003e0.905\u003c/sup\u003e =0.75\u0026thinsp;\u0026times;\u0026thinsp;η (5)\u003c/p\u003e \u003cp\u003eThe viscosity measurement was conducted twice for each pulp sample, and the average result was presented.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Preparation of paper sheets and mechanical characterization\u003c/h2\u003e \u003cp\u003eFor each pulp sample after delignification, hand sheets of about 60 g/m\u003csup\u003e2\u003c/sup\u003e were prepared on a Rapid K\u0026ouml;then Sheet Making Machine according to TAPPI T 205 sp-12. Before papermaking, the pulps were initially exposed to a 2-stage beating procedure (TAPPI T 200 om-89 standard) in the Valey type beater at periods of 9 and 12 minutes. The Schopper-Riegler Freeness Tester was used to determine and the degree of freeness according to the SCAN-C20:65 standard.\u003c/p\u003e \u003cp\u003eUnbeaten and beaten pulp samples were used for the production of the test sheets. After recording the results from each of the physical tests performed on the produced test sheets individually in terms of the SR\u0026deg; degree, the values corresponding to 50 SR\u0026deg; were computed one by one using interpolation.\u003c/p\u003e \u003cp\u003eAfter the time for conditioning (TAPPI T 402 om-88 standard), the test sheets were performed to the following tests.\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003ePreparing of the paper samples to tests: TAPPI T 220 om-88 standard,\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eGrammage: TAPPI T 410 om-88 standard,\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThickness: TAPPI T 411 om-89 standard,\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eOpacity: TAPPI 425 om-91 standard,\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eBrightness: TAPPI T 452 om-88 standard,\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eBurst index: TAPPI T 403 om-91 standard,\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eTearing index: TAPPI T 414 om-88 standard,\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThe breaking length: TAPPI T 494 om-88,\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e2.6. Statistical Analysis (One-way ANOVA)\u003c/h2\u003e \u003cp\u003eThe data was subjected to statistical analysis using the One-way analysis of variance (ANOVA) method, utilising IBM SPSS version 11 software. If the simple analysis of variance indicated a statistically significant difference among the groups, the Newman-Keuls test was employed.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cp\u003eThe oxygen delignification process applied to Kraft pine (Pinus pinea) wood pulp, which exhibited a kappa value of 32.1, intrinsic viscosity of 859.40 cm\u003csup\u003e3\u003c/sup\u003e.gr\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and a yield of 46.8% based on oven dry wood.\u003c/p\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Evaluation of alkali amount optimization results\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e depicts a graph of viscosity and yield changes based on pulp kappa number to understand the selectivity of delignification. As shown in the figure, the yield of delignification decreases linearly with increasing alkali concentration. Previous studies about OD indicates that the alkali charge in delignification is the primary factor influencing pulp qualities and plays a crucial role in determining the pH level of the environment (Sixta et al., \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Kappa number loss due to alkali charge increase and viscosity loss due to polysaccharide degradation verified the yield decline in pulp with the OD procedure. It was attributed to the removal of additional wood components from the pulp by the more severe reaction environment that occurred as the alkaline charge increased. Similarly, Zhang et al. (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) found that as the cooking conditions for soda-oxygen delignification procedures were severer, the pulp's whiteness increased, and the Kappa number declined. The studies conducted by Jafari et al. (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) and Li et al. (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) developed the models that estimate changes in kappa number for different alkaline charge. The rate of delignification and the remaining lignin content in the pulp was calculated by them and they observed that their models correlated with the experimental delignification rate and concluded that increasing the alkali ratio resulted in greater delignification values. In the studies carried out under laboratory conditions, it was stated that the reaction intensified by increasing the alkali ratio and more lignin could be removed from the pulp. However, under harsh reaction conditions, cellulose molecules are oxidized, split, and dispersed in solution as small molecules, in addition to lignin (Suess, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe data showed that the rate of yield loss increased significantly when the alkaline ratio exceeded 3%. Liebergott et al. (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e1985\u003c/span\u003e) found that increasing the alkali ratio during oxygen delignification (OD) led to higher lignin removal and cellulose degradation, despite constant pulp concentration and period of time. In another study, it was underlined that the reaction on lignin and polysaccharides was accelerated due to the increase in pH of the reaction medium as the alkali ratio increased. In addition, it was stated that the selectivity of the reaction decreases in OD performed with a high alkali ratio, resulting in considerable polymerization degree losses of cellulose due to attacks on the carbohydrate fraction (Gullichsen and Fogelholm, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1999\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Evaluation of reinforcements of OD pulps\u003c/h2\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e3.2.1. The effects on chemical properties of pulps\u003c/h2\u003e \u003cp\u003eThe effect of wood gum, a water-soluble hemicellulosic material with a low degree of polymerization, on selectivity during OD was studied in this work. Figure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the data on the characteristics of the pulp produced by adding gum to the OD solution.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIt was found that there was no notable difference among the kappa value up to 3% gum addition when comparing OD3 to both gum additions with the same alkaline amount. However, the kappa number increased when the gum addition exceeded 3%. There may be two causes for this phenomenon. Firstly, the reaction selectivity is enhanced, particularly in terms of the increased retention of hemicelluloses inside the pulp. Due to the increased quantity of hemicellulose, which acts as an intermediary component between cellulose and lignin, a greater amount of lignin was retained in the pulp. The effect shown here is about twice as pronounced for cherry gum compared to guar gum. Previous studies (Van Heiningen and Violette, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2003\u003c/span\u003e and Peşman et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) have indicated that gums containing hemicellulosic structures, but with a lower level of polymerization, enhanced selectivity by exhibiting radical-scavenging activity in the oxygen delignification process. Secondly, the presence of an excessive quantity of hemicellulosic gum in the OD solution prevents diffusion of the solution to the mini-spaces (pores) on the fibre surface, hence limiting oxygen delignification (Van Heiningen and Violette, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Peşman et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003em\u0026uuml;şkaya et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn this study, cherry gum was added to the oxygen delignification medium primarily to prevent viscosity, not to promote delignification. The viscosity of the pulp increased by 1.7% until the amount of gum reached 2% for the ODC series. However, after it reached 3%, the viscosity stopped increasing and started to decrease. Furthermore, it was shown that exceeding a gum concentration of 2% had an adverse effect on the removal of lignin. In a study conducted by Van Heiningen and Violette in 2003, it was shown that the addition of guar gum, an absorbable polymer, to the oxygen delignification medium led to a linear improvement in reaction selectivity. This improvement continued until 2% guar gum was added, resulting in a viscosity improvement of around 5%.\u003c/p\u003e \u003cp\u003eIn this study, it was found that the viscosity-improving effect of cherry gum was less than that of guar gum, due to the different chemical structures. Guar gum is mostly composed of galactomannan-based hemicellulosic components, cherry gum also contains galactomannan but 65% of the structure of cherry gum is made up of pentosan-rich monomeric sugar structures, such as arabinose and xylose (Butler and Cretcher, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e1931\u003c/span\u003e). Based on these results, it was hypothesized that hexosan-type hemicellulosic structures were more efficient for the radical-scavenging mechanisms.\u003c/p\u003e \u003cp\u003eThis work was also aimed to enhance delignification while preserving selectivity by combining the radical-scavenging effect of cherry gum with the more severe oxidative environment generated by peroxide. H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e added to the cherry gum-doped oxygen delignification medium caused a significant decrease in the kappa number of the pulp. In Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, it was also clear that when H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e was added, the viscosity value of the pulp went down. H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e is an effective oxidant that decolorizes and degrades the lignin structure whether used alone or in conjunction with other additives. In studies on the addition of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e to the OD solution, it was determined that peroxide showed a protective impact on pulp viscosity as well as a delignification-enhancing effect. This effect is primarily caused by the rise of lignin-oxidizing perhydroxyl ions and the reduction of detrimental hydroxonium ions.\u003c/p\u003e \u003cp\u003eThe OD experiments involved the addition of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e to a solution containing 2% cherry gum, which had previously been determined as the optimal concentration. Parthasarathy et al. (1990) and Peşman et al. (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) reported that the addition of 0.5% hydrogen peroxide to an OD solution resulted in a 20% and 3% increase in viscosity, respectively. Nevertheless, these findings were not attainable in our investigation. However, the results of this study are noteworthy as they demonstrate that the incorporation of cherry gum and peroxide does not result in a substantial decrease in pulp viscosity. This means that an additional 11% of lignin may be eliminated while seeing a mere 3% decrease in pulp viscosity. The research conducted by Parthasarathy et al. (1990) and Peşman et al. (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003e) found that the delignification rate increased by around 3\u0026ndash;4% without any corresponding change in viscosity. The synergetic impact of cherry gum and peroxide is responsible for this outcome.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, the change in pulp yield caused by the addition of cherry gum was quite little. The increase in the cherry gum ratio resulted in a small increase in pulp production. It is possible to explain the increase with hemicellulose stabilization, more lignin remaining in the pulp due to the increase in kappa number, or some gum remaining in the pulp due to the use of more gum. The difficulties in absorbing and eliminating the cherry gum on the pulp during the washing step made determining the pulp yield quite difficult.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe change in yield was displayed in the same figure as a consequence of the OD conducted by adding guar gum. The yield increased as the quantity of guar gum added to the OD medium increased, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The result has a similar pattern to cherry gum. Therefore, as radical-scavenging additives, cherry gum and guar gum displayed a similar reaction mechanism but could be used interchangeably.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e provides a concise overview of the results obtained from the pulps produced by introducing hydrogen peroxide into the ODC2 system. Upon analysing the graph, it becomes evident that the yield decreases as the peroxide consumption rate increases. From this finding, we could conclude that both lignin and polysaccharides were degraded during delignification. The introduction of hydrogen peroxide into the ODC system increased its oxidative properties, indicating the removal of a portion of the pulp. A similar outcome was observed in a research study employing plum gum (Peşman et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section3\"\u003e \u003ch2\u003e3.2.2. The effects of mechanical properties of pulps\u003c/h2\u003e \u003cp\u003eA comprehensive analysis of variance was performed to evaluate the effects of different additives on the properties of oxygen delignification (OD), utilizing data from the specified five groups. The Newman-Keuls test was applied in cases when significant differences took place from a fundamental analysis of variance. The physical and optical properties that are important to OD-treated pulps were evaluated using defined methods, and the results are presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe effect of some herbal gums and hydrogen peroxide added to the solution medium in the OD process applied to unbleached pine kraft pulp on the physical and optical properties of the pulp.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample Code\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePaper weight (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThickness (\u0026micro;m)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eOpacity\u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eBrightness\u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eBreaking length\u003c/p\u003e \u003cp\u003e(km)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eBurst index (kPa.m\u003csup\u003e2\u003c/sup\u003e.gr\u003csup\u003e\u0026ndash;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eTearing index (mN.m\u003csup\u003e2\u003c/sup\u003e.gr\u003csup\u003e\u0026ndash;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eControl\u003c/p\u003e \u003cp\u003e(K)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e64.83\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;2.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e74.93\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;3.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e92.76\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.91)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e30.04\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.46)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.63\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.62)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2.89\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5.95\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.24)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOD3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e64.60\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;1.90)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e78.00\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;2.73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e83.84\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.75)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e49.69\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.69\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.49)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2.73\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5.48\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.24)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eODC2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.90\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;5.20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e77.82\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;5.05)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e84.27\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;1.68)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e49.71\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.21\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2.71\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.19)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5.79\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.27)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eODC2\u0026thinsp;+\u0026thinsp;P\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e65.70\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;2.70)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e79.12\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;3.63)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80.41\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;1.26)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e54.59\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.31)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.02\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.48)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2.95\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e5.56\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.00)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eODG2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67.10\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;1.20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e81.30\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;2.40)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e85.20\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.69)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e48.88\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.27)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e4.32\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.57)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2.82\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e4.70\u003c/p\u003e \u003cp\u003e(\u0026plusmn;\u0026thinsp;0.07)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe study employed the accepted standard value of 50 SR\u0026deg; (freeness of pulp) as a reference point. Interpolation techniques were used to evaluate the basic strength and optical properties related to this level of freeness, ensuring precision in the study. The difference between the strength properties and the values obtained from the undelignified pine kraft control pulp (K) and the pulp delignified with conventional and modified oxygen delignification (OD) was statistically tested at the 5% significance level.\u003c/p\u003e \u003cp\u003eThere was a limited improvements in breaking length when oxygen delignification was applied to pine kraft pulp without any reinforcements. However, the impact progressively improved by the addition of reinforcements to the OD stage. Individually, the addition of cherry gum and guar gum contribute positively to the breaking length of kraft pine pulp from 3.63 (\u0026plusmn;\u0026thinsp;0.62) to 4.21 (\u0026plusmn;\u0026thinsp;0.65) and 4.02 (\u0026plusmn;\u0026thinsp;0.48) km, respectively. Cherry gum in combination with hydrogen peroxide shown better performance up to 4.32 (\u0026plusmn;\u0026thinsp;0.57) km. Erişir et al. (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2015\u003c/span\u003e) found that an increase in the hemicellulose content in the pulp led to a decrease in the strength properties of the paper sheets. Indeed, similarly, Sp\u0026ouml;nla et al. (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) reported that an increase of the hemicellulose content in the fibers had an adverse impact on strength properties. The study revealed that the addition of gum during oxygen delignification improved the removal of lignin from the fibers, resulting in greater bonding ability and higher breaking resistance, due to the protection of the pulp's viscosity value. Miao et al. (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) quoted by Jie Cai et al. (2015) reported that chemical treatment processes, particularly those consisting of NaOH aqueous solutions, can cause major lateral swelling of the fiber, leading to changes in its bonding properties and strength.\u003c/p\u003e \u003cp\u003eThe previous sections provided comprehensively description of the adverse effects of OD on fibers. The pulp of oxygen delignification with guar gum showed the lowest tear index value of 4.70 mN.m\u003csup\u003e2\u003c/sup\u003e.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Conversely, among the various types of pulps, unbleached pine kraft pulp (K) exhibited the highest tearing index value of 5.95 mN.m\u003csup\u003e2\u003c/sup\u003e.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, as well as the greatest viscosity compared to all other pulps. The tearing index, a measure of the tensile qualities of pulp, is significantly impacted by the decrease in pulp viscosity. Brogdon and Lucia (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) conducted a study on the relationship between Kraft pulp viscosity and paper strength. They found that there is a positive correlation between pulp viscosity and the tearing index. Another study conducted by Carvalho et. al (\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2000\u003c/span\u003e) revealed a correlation between tear index and pulp viscosity, indicating that pulps with greater viscosity exhibited a higher tear index.The statistical analysis indicated that there was no statistically significant difference between the groups at the 5% significance level. It suggests that the increase in delignification did not have an important effect on the paper's burst index.\u003c/p\u003e \u003cp\u003eThe main idea of employing OD is to reduce the remaining lignin concentration in the pulp in order to get a pulp that can be bleached. Basically, it is similar to the continuous soda-oxygen pulping process. Nevertheless, the presence of peroxide and perhydroxyl groups in the solution used for the reaction and the ability to oxidize the remaining lignin structure in the pulp, resulting in a brightening of its color, clearly indicates that this technique has a bleaching effect. According to Gullichsen and Fegelholm (1999), the optical brightening agent (OD) enhances brightness by 15\u0026ndash;20% ISO and the extent of improvement depends on factors such as the kind of raw material, cooking technique, and the amount of residual lignin in the pulp.\u003c/p\u003e \u003cp\u003eIn this study, it was achieved an 18.4% increase in brightness using guar gum reinforced OD on kraft pulp. Additionally, a 19.7% increase was obtained using cherry gum reinforced OD, and a 24.6% increase was achieved using cherry gum and H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e reinforcement. Similarly, Ko\u0026ccedil; et al. (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) reported that reinforced OD as compared to pure OD resulted in approximately 20% improvement in brightness value. Kappa number changes of pulps, which explain the changes in the degree of delignification in pulping, oxygen delignification, and pre-bleaching processes, are an important parameter used in the analysis of the amount of residual lignin in the pulp (Ning et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). According to Eiras et al. (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), the pulp brightness is most affected by the chromophoric groups in the residual lignin. So that, the pulp of cherry gum and peroxide reinforced OD number exhibited the greatest increase in brightness, as well as the highest level of delignification. The results demonstrate the versatility of gums for oxygen delignification and their positive effect on the optical characteristics of pulp. This presents a promising and efficient option for the paper and pulp industry, which is also more ecologically sustainable.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eThis study applied cherry and guar gums, sugar-based natural polymers, as an additive in the reaction medium to enhance the selectivity of the conventional single-stage oxygen delignification (OD) process for Kraft pine pulp. The addition of hydrogen peroxide was also tried to boost delignification while minimizing any substantial decrease in viscosity. First, bleachable pulp resulted in a pulp with a 46.8% yield, a kappa number of 32.1, and a value of 859.4 cm\u003csup\u003e3\u003c/sup\u003e.g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The pulp exhibited a good bleachability.\u003c/p\u003e \u003cp\u003eThe study mainly focused on evaluating the most optimal conditions for OD with and without additives. It was discovered that the optimal alkali charge for OD was 3%. An increase in the alkaline amount has decreased the delignification yield and led to a decrease in the consistency of the pulp. Under the conditions of optimum alkali charge, the application of OD produced a decrease in viscosity of just 6.1% and a removal of lignin at a rate of 54.8% for the pulp. By introducing cherry and guar gums into the reaction media under specified OD conditions, the delignification ratio increased by 2.1% and 6.2% correspondingly. This indicates that both gum affects the selectivity in the OD process. The combination of wood gum and peroxide has both increased delignification and significantly improved the brightness of the pulp. By introducing 1% hydrogen peroxide with 2% cherry gum into the OD, the process of delignification can be enhanced by 13.1%, even if there is only a minimal decrease in viscosity of 1.36%.\u003c/p\u003e \u003cp\u003eThe combined application of cherry gum and hydrogen peroxide reinforcements led to a statistically significant improvement in various strength properties, except for the tearing index. When examining the effects of different reinforcements on mechanical properties, it was observed that additions of both gums increased the strength of the pulp.\u003c/p\u003e \u003cp\u003eThe findings demonstrate that the combination of oxygen delignification and certain reinforcements can enhance the product properties in the paper and pulp industry. Moreover, the use of plant-based reinforcements, such as wood gums, improves the selectivity of the OD process. It offers significant potential for both sustainable development and high-quality products. Ultimately, by tailoring the oxygen delignification process within specific conditions and reinforcing it by suitable enhancements, it still has the potential to improve to a more effective and environmentally friendly method for the paper and pulp industry.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors express their gratitude to the Scientific and Technological Research Council of Turkey (TUBITAK), Grant Number: 110O894 for financial support.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthorship contribution statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eH\u0026uuml;seyin KIRCI:\u003c/em\u003e Investigation, Conceptualization, Design, Funding Acquisition, Project Administration, Analysis, Visualization, Reviewing and Editing\u0026mdash;First Draft of the Manuscript\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAyşeg\u0026uuml;l İSKEFYELİ:\u003c/em\u003e Data Collection, Analysis, Writing\u0026mdash; First Draft of the Manuscript\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEvren ERSOY KALYONCU:\u003c/em\u003e Data Collection, Reviewing and Editing\u0026mdash; First Draft of the Manuscript\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEmir ERİŞİR:\u003c/em\u003e Material Preparation, Investigation, Writing, Reviewing and Editing \u0026mdash; First Draft of the Manuscript, Visualization\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) [grant number 110O894].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData will be made available on request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclarations Confict of interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no confict of interest. Ethical approval Ethics approval was not required for this research\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAkim, L. G., Colodette, J. L., Argyropoulos, D. S. (2001) Factors limiting oxygen delignification of kraft pulp. Canadian Journal of Chemistry, 79(2), 201\u0026ndash;210. DOI: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1139/v01-007\u003c/span\u003e\u003cspan address=\"10.1139/v01-007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBajpai, P., (2005) Cleaner Production Measures in Pulp and Paper Processing. In Environmentally Benign Approaches for Pulp Bleaching, Developments in Environmental Management, Elsevier, pp. 119.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrogdon, B. N., Lucia, L. A. 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TAPPI journal, 83(2).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Kraft pulp, Oxygen delignification, Cherry gum, Polysaccharide stabilization, Environmentally friendly bleaching","lastPublishedDoi":"10.21203/rs.3.rs-3882713/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3882713/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe objective of this study was to decrease the adverse effects of radicals created in the reaction medium by adding cherry gum or guar gum, which are sugar-based polymers, into the oxygen delignification (OD) solution used in the bleaching process of pine wood pulp produced by the kraft process. In order to enhance the dissolution of lignin, peroxide was introduced into the oxygen delignification solution, resulting in the formation of a more intensive oxidative environment. The impact of each gum addition on cellulose and hemicelluloses during oxidation processes was assessed by determining pulp viscosity, kappa number, and yield values. The addition of 2% cherry gum to the OD pulp resulted in a 2.1% increase in the removal of residual lignin and a 1.9% increase in viscosity compared to the pulp without cherry gum. Similar results were also achieved in the examination of OD pulps reinforced with guar gum. The study revealed that using cherry gum and peroxide-reinforced OD pulps resulted in the lightest-colored pulps. It was observed that additions of both gums increased the strength of the pulp except for the tearing index.\u003c/p\u003e","manuscriptTitle":"The enhanced selectivity of oxygen delignification of kraft pine wood pulps: The effects of pentosane-based cherry and guar gum additions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-24 13:17:29","doi":"10.21203/rs.3.rs-3882713/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"706ff548-d9d4-45ce-ad99-bc168cdf77d7","owner":[],"postedDate":"January 24th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-01-30T15:48:14+00:00","versionOfRecord":[],"versionCreatedAt":"2024-01-24 13:17:29","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-3882713","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3882713","identity":"rs-3882713","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}