Soda Pulping Research Articles

Effects of Lignin Derivatives on Cross-Link Density and Dielectric Properties in the Epoxy-Based Insulating Materials for Printed Circuit Boards

Bio-plastics are made from renewable biomass sources. We focus on lignin and develop epoxy resins containing lignin derivatives. We describe the preparation and application of epoxy resin containing lignin as a matrix. Soda-lignin (SLG) is obtained from black liquor in a soda pulp process. First, we use a lignin manufacturing process in which a methanol extraction method enabled reduction in the molecular and hydroxyl equivalent weights of lignin and removal of SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and cellulose. Second, we investigate the ratio of diglycidyl ether of bisphenol-A (DGEBA) and methanol extraction SLG (me-SLG). From the viewpoint of cross-linking density and dielectric properties, 100/84 phr in the DGEBA/me-SLG casting system is found to be preferable. Finally, we try to fabricate an insulating material made up of DGEBA/me-SLG for an aluminum-based printed circuit board, and it achieves standard values.

Physicochemical characterization of alkaline and ethanol organosolv lignins from oil palm (Elaeis guineensis) fronds as phenol substitutes for green material applications

In the present work, lignin isolation and physicochemical features from oil palm fronds (OPF) black liquor using Kraft, soda and organosolv pulping have been studied. The characterization of lignin samples by means of FTIR, 1H and 13C NMR has shown that different types of hydroxyl functional groups were obtained from different delignification processes. It was revealed that the lignin samples contained substantial amounts of non-condensed guaiacyl and syringyl unit with fewer p-hydroxyphenyl units. The GSH molar ratio of Kraft, soda and organosolv lignin was assigned to 26:51:21, 21:49:30 and 23:67:10, respectively, upon quantification. The significant differences in the physicochemical features of the lignin isolated with alkali and organosolv treatments may be of great interest as a promising alternative for its revalorization.

Delignification of Phragmites karka – a Wetland Grass – by Soda Pulping Process

Phragmites karka, a common wetland grass, was delignified by the soda pulping process, and all the operating parameters were optimized. The effects of both anthraquinone and surfactant on pulp yield and kappa number at optimum pulping conditions were also investigated. The pulp was beaten at different beating levels to optimize different mechanical strength properties. A detailed morphological study of soda-AQ pulp of P. karka was conducted by scanning electron microscopy.

Biological removal of chloro-organic compounds from bagasse soda pulp bleaching effluent by Coriolus versicolor

The potential of rainbow fungus (Coriolus versicolor) for bioremediation of bagasse soda pulp bleaching effluent containing chlorinated organic compounds was investigated without co-substrate addition. Initially, the effect of each of the operating variable including time, temperature, pH, and biomass on color reduction was investigated. The highest color reduction (percentage of the original value) was observed applying a treatment time of 6 days (58%), a pH of 3 (48%), a biomass dose of 9 g L-1 (59%), and a temperature of 35°C (48%). Then, the combined effect of parameters was studied to reach the best combinations of parameters leading to the highest color reduction. The highest performance of rainbow fungus on color reduction (66%) was observed when applying the combination of variables including temperature, treatment time, biomass dose, and pH combination of 35°C, 6 days, 9 g L-1, and 3, respectively. At this condition, COD and BOD of effluent were decreased by 45% and 53%, respectively. It was also found that Coriolus versicolor can efficiently reduced various toxic compounds; chlorophenols, chloroguaiacols, and chlorocatechols present in the effluent to the levels less than their lethal concentration (96LC50) even without addition of cosubstrate. In general, rainbow fungus can efficiently modify the undesirable physico-chemical characteristics of bagasse soda pulp bleaching effluent.

Alkali consumption of aliphatic carboxylic acids during alkaline pulping of wood and nonwood feedstocks

Abstract The carbohydrate degradation products have been examined, which are formed during the conventional kraft pulping of a softwood, hardwoods, bamboo, and wheat straw as well as soda and soda-anthraquinone pulping of wheat straw. The focus was on “volatile” acids such as formic and acetic acids and “nonvolatile” hydroxy monocarboxylic and dicarboxylic acids. The different consumption profiles were obtained for the charged alkali required for the neutralization of these aliphatic acids depending on the feedstock and the cooking method. The relative composition of the acid fraction in the black liquors of softwood and hardwood and nonwood feedstocks showed characteristic variations. However, in the case of wood kraft pulping, the variations in cooking conditions (effective alkali 19–21% and cooking temperature 155–170°C) had no significant effect on the acid composition. The total amount of volatile and hydroxy acids formed during pulping at a typical target κ number level for each feedstock ranged from 78 to 174 kg ton-1 based on o.d. feedstock. It was highest in birch kraft pulping and lowest in wheat soda-anthraquinone pulping.

Removal of silicon from green liquor with carbon dioxide in the chemical recovery process of wheat straw soda pulping

Green liquor in the chemical recovery process of wheat straw pulping was treated with carbon dioxide to precipitate silicon by a one-step process and a seeding process to address problems caused by high silicon content. The total silicon removal, the particle size, and the sedimentation performance of silica were investigated. The results showed that the pH of green liquor decreased with increasing amounts of carbon dioxide, becoming stable after the pH decreased to 8.2. Reaction temperature had no significant effect on the removal of silicon. About 99% of silicon removal was achieved at a pH of 9.2 at room temperature. In the one-step process, the particle size increased and the silica sedimentation performance improved with decreasing pH. The particle size decreased and the sedimentation performance improved with increasing reaction temperature. At a pH of 9.5 and reaction temperature of 80°C, the particle size was 10.43 μm. In the seeding process, 40% green liquor was treated with carbon dioxide at 80°C until the pH was about 10.5, then the 40% treated green liquor was mixed with the remaining 60% of green liquor. The mixture was then treated with carbon dioxide at a reaction temperature of 80°C until the pH reached 9.5. In that situation, the particle size reached 14.11 μm. Compared with the one-step process, the particle size of silica generated by the seeding process was bigger and the sedimentation performance was improved.

Evaluation of Defiberation by Organosolv Ethanolamine Pulping for Integral Utilization of Oil Palm EFB

Organosolv ethanolamine pulping for oil palm empty fruit bunches(EFB) were evaluated in this study. The screen yield by the ethanolamine pulping were higher than that by the soda pulping at the same operation conditions. The higher concentration of ethanolamine solvent resulted in the higher yield and the lower contents of residual lignin. The EFB pulp fibers were the narrower in fiber width but the higher in coarseness than those of the hardwood pulp fiber, while the fiber length of the EFB pulp fiber were similar to that of the hardwood fiber. The intrinsic zero span tensile testing showed the EFB pulp fiber by the 80% ethanolamine pulping were the stronger than the fiber by the soda pulping. The results of this study supported that the ethanolamine pulping could be used as an alternative pulping method for the EFB.

Papermaking potential of rapeseed straw, a new agricultural-based fiber source

Abstract The main papermaking characteristics of rapeseed straw (Brassica napus L.) as an agricultural residue were investigated. The average fiber length, width, lumen, and cell wall thickness were found to be 1.03 mm, 28.00 μm, 19.1 μm, and 4.91 μm, respectively. Cellulose, lignin, holocellulose, acetone-soluble extractives and ash content were determined as 41.66, 16.00, 78.9, 1.63, and 3.46%, respectively. Soda and soda-anthraquinone (AQ) pulping were conducted using 16, 18, and 20% sodium hydroxide and 0.2% AQ in soda-AQ pulping, based on oven-dried straw, cooking temperatures of 175 and 185 °C, cooking times of 40 and 70 min, and liquor-to-straw ratio of 8:1. The results showed that lower Kappa number, higher screened pulp yield, and improved bonding strength properties were obtained in the soda-AQ pulping at even 2% less alkali consumption as compared to the soda process. In general, the pulp strength characteristics of rapeseed straw were comparable to those of hardwoods and short-fiber non-wood plants.

Oxygen Delignification of Wheat Straw Soda Pulp with Anthraquinone Addition

Oxygen delignification of wheat straw soda pulp with the addition of anthraquinone (AQ) was conducted to evaluate the effects of AQ on pulp quality. The pulp yield, kappa number, intrinsic viscosity, and brightness were selected as the properties to optimize oxygen delignification. The optimal pulp was obtained via grey relational analysis with an alkali charge of 3%, oxygen pressure of 0.5 MPa at 120 °C for 85 min, and with 0.05% AQ. In contrast to conventional oxygen delignification, the addition of AQ produced pulp with a higher yield, and it did not generate other negative impacts on pulp kappa number, viscosity, and brightness. The reaction mechanism of AQ in oxygen delignification was different from that in alkali pulping.

Rapid Optimization of Typha Grass Organosolv Pretreatments Using Parallel Microwave Reactors for Ethanol Production

A comparative study of organosolv process was performed at laboratory scale using traditional stainless steel batch reactor with parallel microwave (MW) reactors. Ethanol (with sulfuric or soda catalyst), formic acid, and performic acid organosolv processes were first optimized for the pretreatment of Typha capensis using MW reactors. The best conditions based on mass balance and Klason lignin content were reassessed using a traditional pressure steel reactor. The enzymatic hydrolysability of soda process revealed better results (reducing sugar yields = 77–87%) as compared to the sulfuric acid process (reducing sugar yields = 57–66%). Substantially higher delignification and better enzyme hydrolysability were observed for the formic acid process with hydrogen peroxide catalyst. This process produced a pulp with very low residual lignin ( 85%). It can be concluded from this study that parallel microwave technology could be used for rapid optimization of bio...

Alkaliphilic Endoxylanase from Lignocellulolytic Microbial Consortium Metagenome for Biobleaching of Eucalyptus Pulp

Enzymatic pre-bleaching by modification of pulp fibers with xylanases is an attractive approach to reduce the consumption of toxic bleaching chemicals in the paper industry. In this study, an alkaliphilic endoxylanase gene was isolated from metagenomic DNA of a structurally stable thermophilic lignocellulose-degrading microbial consortium using amplification with conserved glycosyl hydrolase family 10 primers and subsequent genome walking. The full-length xylanase showed 78% sequence identity to an endo-beta-1,4-xylanase of Clostridium phytofermentans and was expressed in a mature form with an N-terminal His6 tag fusion in Escherichia coli. The recombinant xylanase Xyn3F was thermotolerant and alkaliphilic, working optimally at 65-70 degrees C with an optimal pH at 9- 10 and retaining >80% activity at pH 9, 60 degrees C for 1 h. Xyn3F showed a Vmax of 2,327 IU/mg and Km of 3.5 mg/ml on birchwood xylan. Pre-bleaching of industrial eucalyptus pulp with no prior pH adjustment (pH 9) using Xyn3F at 50 IU/g dried pulp led to 4.5-5.1% increase in final pulp brightness and 90.4-102.4% increase in whiteness after a single-step hypochlorite bleaching over the untreated pulp, which allowed at least 20% decrease in hypochlorite consumption to achieve the same final bleaching indices. The alkaliphilic xylanase is promising for application in an environmentally friendly bleaching step of kraft and soda pulps with no requirement for pH adjustment, leading to improved economic feasibility of the process.

Effect of processing variables on efficiency of eucalyptus pulps for internal curing

Abstract This study evaluates the effect of fiber composition and morphology, as altered by various papermaking processes, on internal curing performance of hardwood eucalyptus pulp fibers. The autogenous deformations of cement pastes containing each of five different eucalyptus pulps—unbleached soda pulp, bleached soda pulp, unbleached kraft pulp, bleached kraft pulp, and semi-chemical pulp—were examined and analyzed in the context of the known relevant chemical composition and morphology, e.g., cellulose-to-hemicellulose ratio, cell wall thickness, and “hard to remove” (HR) water content. The results revealed that the internal curing efficiency of these pulps is related more strongly to their physical morphology than chemical composition, as measured by cellulose-to-hemicellulose ratio. The partial defiberization during mechanical treatment associated with semi-chemical pulping resulted in fiber fracture and also produced materials which were poorly dispersible; together, these factors limit internal curing capability of semi-chemical pulp. The soda fibers, both unbleached and bleached, with their thicker cell wall and higher HR water content were more effective for internal curing than kraft fibers. It is proposed that for hardwood pulp fibers a slower rate of entrained water release is beneficial for internal curing.

Ethanol from Nordic wood raw material by simplified alkaline soda cooking pre-treatment

Ethanol production from lignocellulosic raw materials will generate multiple streams, since only a certain fraction of the material can be converted into sugars and then fermented to ethanol. This requires a ‘poly-generation’ approach, where by-products also must have high value (e.g. lignin, sugars from hemicellulose). To reach the large scale required for profitability, it is proposed that the best way is to integrate the new processes with existing industries, preferably those that already operate biomass-to-materials or biomass-to-fuels plants. One of the largest industry branches in this respect is the pulp and paper industry. Production of second generation ethanol (or other products) via sugars from lignocellulosic materials includes a relatively costly pre-treatment of the raw material in order to separate the lignin from the cellulose. This separation of the wood components already takes place in the chemical pulp mill, and the long proven technology in pulp production known as soda cooking (pre-treatment under alkaline conditions) is further evaluated in this study. It can be directly integrated into the recovery of chemicals and energy in the pulp mill. The pre-treatment of the lignocellulosic material studied in this work is alkaline and sulphur-free, and results in a technically pure cellulose to be fed to the hydrolysis stage, which makes it different compared to most of the other processes that aim to produce ethanol from lignocelluloses. The process chain from enzymatic hydrolysis to ethanol is very similar to that being used today for grain ethanol.The aim of this study was to define the conditions in alkaline pre-treatment stage for the separation of wood to a carbohydrate fraction for hydrolysis and ethanol production, and to a lignin fraction for the production of lignin products. Aspen (Populus tremula) and pine (Pinus sylvestris) wood from Nordic mills were studied. The reference case was alkaline pre-treatment according to the well-known soda pulping technique. The pulps of alkaline pre-treated aspen could be enzymatically hydrolysed very efficiently and fermented to ethanol with high yields (82–88% ethanol yield from theoretical maximum). It should be possible to use raw material of lower quality and cost than wood from the pulp industry. However, it can then be important to be able to take out non-process elements (NPEs) that otherwise accumulate in the process. This can be done by introducing an acidic prehydolysis stage prior to the alkaline fractionation. The content of Mg and Mn ions in the wood was possible to reduce by 85–90% and Ba and Ca ions by 75–80%. Potassium was virtually completely removed during the acidic pre-treatment stage.

Effects of hot water pre-extraction on surface properties of bagasse soda pulp

In this work, the effects of hot water pre-extraction of depithed bagasse on the soda pulping and surface properties were studied. The conditions of hot water pre-extraction were: maximum temperature 170°C, heat-up time 90min, time at maximum temperature 10min, and solid to liquor ratio (S:L) 1:8. Consequently, the pre-extracted and un-extracted bagasse chips were subjected to soda pulping at 160°C for 1h with 11, 14 and 17% active alkali charge and an S:L of 1:5. The results showed that the hot water pre-extraction increased bagasse surface texture porosity by hemicellulose degradation. Therefore, the delignification was faster for pulping of pre-extracted samples. At a certain charge of alkali, pre-extracted samples showed higher screened yield and lower Kappa number. For instance, at 17% alkali charge, pre-extracted bagasse gave 11.3% higher pulp yield compared with the un-extracted ones. Inverse gas chromatography (IGC) results showed that the hot water pre-extraction changed the active sites on the bagasse surface, decreasing the dispersive energy and the basicity character, and affected the particle morphology. The pulping process decreased the hydrophobicity and the basicity of the bagasse surface. The surfaces of un-extracted and pre-extracted bagasse pulps had similar properties but different morphology. The pulps present higher surface area and permeability with more reactive capacity.

English

Influence of variables [soda, (0.5 to 3.0%), hydrogen peroxide (1.0 to 10.0%) and time (1 to 5 h)] in the bleaching of soda pulp of&nbsp;Hesperaloe funifera, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models had reproduced the results of Kappa number, brightness and viscosity of the pulps with errors less than 10 and 15%, respectively. By simulating the bleaching process of pulp&nbsp;H. funifera, with the polynomial and neural fuzzy models, the optimal values of operating variables can be found, so that the properties of bleached pulps differ little from their best values and instead will save chemical reagents, energy and plant size, operating with lower values of operating variables. Thus, by application of polynomial models, it was found that operating with a soda concentration of 0.5%, a hydrogen peroxide concentration of 5.5% and for a processing time of 3 h, it was possible to get a pulp with a brightness of 65.9% and a viscosity of 587 ml/g. &nbsp; Key words:&nbsp;Pulp bleaching,&nbsp;Hesperaloe funifera, hydrogen peroxide, neural fuzzy model, polynomial model.

Pre-extraction of hemicelluloses from bagasse fibers: Effects of dry-strength additives on paper properties

The aim of this study was to further evaluate the viability of the integrated pulp mill biorefinery concept. On one side the properties of hot-water pre-extractions were studied, in order to determine the effect of extraction on soda pulping and bleachability. On the other side, the performance of two dry-strength agents on the paper properties obtained from extracted and un-extracted (control) samples were investigated. It was found that hemicelluloses removal of the depithed bagasse chips was 24.6% at 140°C for 10min with a solid to liquor ratio (S:L) of 1:8 (w/w), and that mass removal increased with extraction time and temperature. The hemicelluloses removal reached 65.5% at 170°C for 30min. The residual extracted bagasse were subjected to soda pulping at 160°C for 1h with 11, 14 and 17% active alkali charge and a S:L of 1:5 (w/w). Conventional elemental chlorine free bleaching (D0ED1) sequence was also used to compare the results with the un-extracted ones. Compared with the control sample, the overall pulp yield for extracted bagasse increased considerably while Kappa number and rejects decreased moderately. In addition, yield and Kappa number of the pulps improved with increasing alkali charge from 11% to 17%. After pre-extraction, better brightness compared with the control pulp was also shown. However, hot-water extraction was found to negatively impact some pulp properties including decreases in burst and tensile indices while addition of chitosan and cationic starch could improve the strength properties. Overall, papers treated with chitosan gave superior mechanical properties compared to the papers treated with cationic starch.

Efficacy of Chemical Oxidation and Coagulation for COD and Color Reduction from Pulp Mill Effluent

AbstractIn a pulp and paper mill, the highly colored wastewater generated from the pulping process requires pretreatment before the biological purification process because of the presence of recalcitrant lingo-cellulosic compounds. For the present study, the black liquor was prepared in the laboratory by digesting the sugarcane baggase using the soda process, which was further diluted before use in the experimental study. The wastewater [pH=13.0, chemical oxygen demand (COD)=5,120 mg/L] was treated by two processes: wet oxidation (WO) (both noncatalytic and catalytic) and coagulation. Catalytic WO (CWO) experiments were conducted in the presence of 60% CuO/40% CeO2 at temperatures ranging from 130 to 170°C and total pressures of 0.95 MPa. During the CWO process, the maximum COD and color removals were found to be approximately 51 and 71%, respectively. Coagulation followed by noncatalytic WO exhibited the best performance with overall COD and color reductions of approximately 77.5 and 87%, respectively. ...

Study of Rice Husk Pulping for utilization of Rice Husk Fiber

The rice husk is one of the major agricultural residue in KOREA. In this paper, the effects of various pulping conditions on the properties of rice husk pulp and handsheets made of rice husk fiber were evaluated in order to utilize the rice husk as an alternative source for wood pulp. Two typical alkali pulping, such as soda pulping and Kraft pulping were applied with various conditions of the pulping processes. The higher effective alkali and higher pulping temperature resulted in the higher efficiency in removal of lignin and ash, which leaded to the higher strength properties of handsheets made of rice husk fiber, but the lower yield of rice husk pulp. The better efficiency in production of rice husk pulp and the stronger handsheets were obtained by the Kraft pulping.

Anthraquinone polymer catalysts for alkaline delignification of lignocellulosic matter. Part 2. Action in soda pulping conditions on softwood and phenolic β-O-4 lignin models

Abstract Two hydrophobic and one hydrophilic anthraquinone (AQ) polystyrene catalysts were tested under soda pulping conditions on thermomechanical fibers, and the results were evaluated based on commercial AQ. Hydrophobic and hydrophilic polymers had efficiency gains of 23%–28% and 57%, respectively, compared to AQ (100% efficiency). Hydrosolubility of AQ polymers played a major role in delignification efficiency, a property that allows a better contact with lignocellulosic fibers. Hydrophobic copolymers were stable under pulping conditions and preserved their catalytic effect entirely by contrast to the hydrophilic AQ, as demonstrated by recovery yields after pulping and catalytic action of the recovered copolymers. Studies on lignin models confirmed that the hydrophilic AQ polystyrene is a better catalyst under soda pulping conditions than the hydrophobic ones. It was demonstrated that AQ polystyrene polymers react with lignin models by electron transfer mechanisms.

Coupling of solar-assisted advanced oxidative and biological treatment for degradation of agro-residue-based soda bleaching effluent

This study evaluates the effect of integrated solar-assisted advanced oxidation process (AOP) and biological treatment on the extent of degradation of effluents from chlorination (C) and first alkaline extraction (E(1)) stages of soda pulp bleaching in agro-residue-based pulp and paper mill. Biodegradation of the effluents was attempted in suspended mode using activated sludge from the functional pulp and paper industry effluent treatment plant acclimatized to effluents in question. The photocatalytic treatment was employed using zinc oxide (ZnO) in slurry mode for decontamination of effluents in a batch manner and the degradation was evaluated in terms of reduction in chemical oxygen demand. The biological treatment (24h) of C and E(1) effluent resulted in 30 and 57% of degradation, respectively. Solar-induced AOP of C and E(1) effluents resulted in 53 and 43% degradation under optimized conditions (2.5gL(-1) ZnO at pH8.0) after 6h of exposure. For C effluent, a short duration of solar/ZnO (1h) prior to biological treatment reduced the time required at biological step from 24 to 12h for almost same extent (92%) of degradation. However, sequential biological treatment (24h) followed by solar/ZnO (2h) resulted in 85.5% degradation. In contrast, in the case of E(1) effluent, sequential biological (24h)-solar/ZnO (2h) system effectively degrades effluent to 95.4% as compared to 84.8% degradation achieved in solar/ZnO (2h)-biological treatment (24h) system. In the present study, the sequencing of photocatalysis with the biological treatment is observably efficient and technically viable process for the complete mineralization of the effluents.