Chemical analysis of polysaccharides in plantation eucalypt woods and pulps

Chemical Study of Kraft Lignin during Alkaline Delignification of E. urophylla x E. grandis Hybrid in Low and High Residual Effective Alkali

Article

May 2019

Chips from E. urophylla x E. grandis hybrid were subjected to kraft cooking using two different approaches: low and high residual effective alkali. The lignin remaining in the pulps were analyzed for hydroxyl and carboxyl functional groups. For both pulping cases the kappa number varied between 14 and 26. Significant yield gains were observed when kraft cooking was terminated with low residual effective alkali (L-REA) in contrast to high residual effective alkali (H-REA) at a given kappa number. The L-REA pulps also tended to contain higher lignin and lower HexA contents than the H-REA pulps at a given kappa number. Cellulolytic enzyme lignin (CEL) was isolated from the studied pulp’s residual lignins and their hydroxyl functional group distributions were quantified using a method involving 31P-NMR. Analysis of residual lignins isolated from L-REA and H-REA cooking indicated that L-REA had high contents of phenolic hydroxyl groups and carboxylic acid groups in relation to the H-REA pulps. This work demonstrates the varied lignin chemistry one can expect when varying residual effective alkali levels during kraft pulping and how this parameter can influence downstream unit operations and overall process performance.

INFLUÊNCIA DA IDADE DE CORTE DE CLONES DE Eucalyptus grandis E HÍBRIDOS DE Eucalyptus grandis x Eucalyptus urophylla NA COMPOSIÇÃO QUÍMICA DA MADEIRA E POLPAÇÃO KRAFT

Article

Full-text available

Mar 2017

Os recentes esforços na melhoria da qualidade da madeira para o abastecimento das fábricas de celulose e papel têm focado em muitos pontos, dentre estes, a influência das características químicas da matéria-prima no processo produtivo e na qualidade do produto final. Considerando a atual demanda por árvores mais jovens, o efeito da idade de corte da madeira na composição química e nas variáveis de processo, torna-se uma questão importante para as indústrias do setor. Em função disto, o objetivo do presente estudo foi caracterizar clones de eucalipto, Eucalyptus grandis e híbridos Eucalyptus urograndis, ambos em diferentes idades de corte (1 a 8 anos) quanto às suas composições químicas e parâmetros de polpação kraft. Ambas as composições químicas das madeiras mostraram variações estatísticas significativas devido às suas diferentes idades de corte. O teor de glicanas, assim como o teor de celulose, densidade básica e extrativos, aumentaram com o aumento da idade de corte das árvores, enquanto o teor de xilanas e demais carboidratos que compõem as hemicelulose, tenderam a diminuir com o aumento da idade de corte, assim como os ácidos urônicos, grupos acetila, lignina, cinzas e relação S:G da lignina da madeira. As amostras com 5 anos de idade mostraram o melhor rendimento na polpação kraft para número kappa 17, e este rendimento (número kappa 17) mostrou forte correlação com o teor de glicanas.

Effect of Mechanical Treatment of Eucalyptus Pulp on the Production of Nanocrystalline and Microcrystalline Cellulose

Article

Full-text available

May 2021

This study aimed to assess the effect of mechanical pretreatment on bleached eucalyptus kraft pulp fibers and investigate the influence of reaction time and temperature on the properties and yield of nanocrystalline cellulose (NCC) and microcrystalline cellulose (MCC). Two types of pulps were hydrolyzed, pulp 1 (control, whole fibers) and pulp 2 (mechanically pretreated, disintegrated fibers). NCC and MCC particles were obtained by sulfuric acid hydrolysis (60% w/w) of eucalyptus pulps under different conditions of time (30–120 min) and temperature (45–55 °C). Physical treatment of kraft pulp facilitated acid hydrolysis, resulting in higher NCC yields compared with no pretreatment. The morphologic properties and crystallinity index (CI) of NCC and MCC were little affected by pulp pretreatment. NCC particles obtained from pulps 1 and 2 were needle-shaped, with mean diameters of 6 and 4 nm, mean lengths of 154 and 130 nm, and CI of 74.6 and 76.8%, respectively. MCC particles obtained from pulps 1 and 2 were rod-shaped, with mean diameters of 2.4 and 1.4 µm, mean lengths of 37 and 22 µm, and CI of 73.1 and 74.5%, respectively. Pulps 1 and 2 and their respective NCC and MCC derivatives had a cellulose I crystalline structure.

Mechanics of Natural Curauá Textile Reinforced Concrete

Article

Full-text available

Jul 2019

In the present work, textile-reinforced concrete (TRC) specimens were produced using high-performance natural curauá unidirectional fabrics as reinforcement. Portland cement was partially replaced by pozzolanic materials to produce a matrix with low calcium hydroxide content. Composites with different numbers of layers and thicknesses were produced. Their mechanical behaviour was evaluated through tensile testing. Crack formation was investigated using an image capture procedure and a digital image correlation (DIC) methodology. From the DIC analysis, it was possible to provide an estimate of the number of cracks, the mean crack spacing and width during the tensile tests. The curauá textile was shown to be a promising reinforcement, resulting in a composite with multiple cracking formation and strain-hardening behaviour. This newly developed composite showed similar mechanical behaviour to that of man-made fibre-reinforced composites. Combined with its low cost and sustainability characteristics, the curauá TRC may represent a good alternative to conventional construction materials.

Dissolving pulp production from bamboo

Article

Dec 2011
BIORESOURCES

Commercial bamboo chips were evaluated as raw material for dissolving pulp production. The chips were auto-hydrolyzed (AH) and subsequently cooked by the NaOH/AQ process and bleached to full brightness with the O-CCE-D-(EP)-D-P sequence. The term CCE designates a cold caustic extraction stage. The bamboo chip chemistry (22.4% lignin, 19.5% xylans, 49.3% cellulose, 16.8% total extractives, and 1.5% ash) was apparently unfavorable; however high quality dissolving pulp was produced using the aforementioned technologies, even when compared to results obtained with traditional eucalypt commercial wood chips. The pulp showed high brightness (92.4 % ISO) and α-cellulose content (94.9%). Its contents of hemicelluloses, extractives and ash were within acceptable levels for a dissolving pulp aimed at viscose rayon production. Thus, the bamboo chip furnish investigated can be regarded as a viable raw material for dissolving pulp production.

Evaluation of kraft lignin and residues of sawmill for producing briquettes

Article

Full-text available

Aug 2022

The aim of becoming a society based on the rational utilization of the natural resources, has led to the consideration of many alternatives by academic and industrial sectors. The forest sector may be particularly prominent in trying to achieve these goals when using residues of their processes, for timber and pulp production. One of the most important requirements in society is the energy production. Co-products of wood processing and cellulose mills can be used for bioenergy generation. The densification of biomass involves handling, transportation and storage issues, and furthermore, when industrial forest residues such as lignin are added to this biomass, the final energetic product may have some improved properties, adding value to the chain. The purpose of this study was to evaluate the usage of the woody industrial waste, the sawdust from Joannesia princeps Vellozo enriched with Kraft lignin as an additive, aiming to produce briquettes. One of the main findings from this work was the possibility to obtain a briquette with better properties (higher bulk density and higher resistance) when using 6% of Kraft lignin as an additive and a pressure of 1500 PSI.

Comparison of pre-treatments mediated by endoglucanase and TEMPO oxidation for eco-friendly low-cost energy production of cellulose nanofibrils

Article

Full-text available

Aug 2022
ENVIRON SCI POLLUT R

Specific kinds of enzymes have been used as an eco-friendly pre-treatment for mechanical extraction of cellulose nanofibrils (CNFs) from vegetal pulps. Another well-established pre-treatment is the 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)–mediated oxidation, which has gained considerable attention. Pre-treatments assist in fiber swelling, facilitating mechanical fibrillation, and reducing energy consumption; however, some of these methods are extremely expensive. This work aimed to evaluate the influence of enzymatic pre-treatment with endoglucanase on the energy consumption during mechanical fibrillation of cellulose pulps. Bleached pulps from Eucalyptus sp. and Pinus sp. were pre-treated with endoglucanase enzyme compared to TEMPO-meditated oxidation. Average diameters of CNFs pre-treated with enzymes were close to that found for TEMPO-oxidized nanofibrils (TOCNFs). Results showed that enzymatic pre-treatment did not significantly modify the pulp chemical and morphological characteristics with efficient stabilization of the CNFs suspension at higher supernatant turbidity. Energy consumption of pulps treated with endoglucanase enzymes was lower than that shown by pulps treated with TEMPO, reaching up to 58% of energy savings. The enzyme studied in the pulp treatment showed high efficiency in reducing energy consumption during mechanical fibrillation and production of films with high mechanical quality, being an eco-friendly option for pulp treatment.

Alkaline Pretreatment Facilitate Mechanical Fibrillation of Unbleached Cellulose Pulps for Obtaining of Cellulose micro/nanofibrils (MFC)

Article

Jun 2022

Energy expenditure is a limiting factor for the production of cellulose micro/nanofibrils in mechanical processing. This study evaluated the effect of novel alkaline pretreatments on unbleached Eucalyptus sp. pulps (hardwood) and Pinus sp. cellulose (softwood) to facilitate the production of cellulose nanofibrils by mechanical fibrillation and reduce the energy consumed by the mill. Pretreatments with NaOH in concentrations of 5% for 2 h and 10% for 1 h and 2 h and a hybrid pretreatment with 5%/16% NaOH/ H2O2 for 2 h were evaluated. The 10% pre-treatment was done at 1 h and 2 h to evaluate the effect of the less aggressive treatment (1 h). The morphology, chemical composition, turbidity of the fibers/suspensions, mechanical properties, fibrillation quality index and energy expended during the fibrillation were evaluated for each pretreatment. The less aggressive pretreatments produced micro/nanofibrils with fewer passes of the pulp through the fibrillator, which effectively facilitated extraction with lower energy consumption. The hybrid pretreatment did not show satisfactory results in reducing energy consumption, and the quality of the nanofibrils produced by this pre-treatment was inferior to the others. This study showed innovation in performing novel and efficient NaOH and hybrid (NaOH/H202) pretreatments on commercial unbleached pulps to obtain pulp micro/nanofibrils.

Optimizing cellulose microfibrillation with NaOH pretreatments for unbleached Eucalyptus pulp

Article

Full-text available

Dec 2021
CELLULOSE

Microfibrillated cellulose (MFC) is a form of biopolymer that stands out because of its versatile use. However, the process of obtaining MFC requires adjustments to provide the increase of microfibrillation in industrial scale. Thus, this study aimed to apply pretreatments with NaOH in unbleached Eucalyptus sp. fibers to optimize the microfibrilation process, in order to evaluate the effect of drying and not drying the fibers after pretreatments for reduction of energy consumption. Treatments of MFC with NaOH at 5% with 2 h of reaction and by 10 wt% were evaluated for the resulting morphology, chemical composition, and energy consumption. The length and width of the pulp fibers pretreated with NaOH decreased significantly, mainly with hasher pretreatments. Pretreating fibers with 5 wt% NaOH for 2 h increased the water retention value (WRV), in addition to presenting the lowest energy consumption for fibrillation, promoting energy savings of up to 48%. Pulps that were non-dried after the NaOH pretreatments resulted in easier microfibrillation and lower energy consumption when compared to dried pulp, which shows the negative impact of drying on the fibers to obtain MFC. Graphic abstract

Evaluation of changes in cellulose micro/nanofibrils structure under chemical and enzymatic pre-treatments

Article

Jul 2021
HOLZFORSCHUNG

The objective of the present work was to evaluate the use of Raman microspectroscopy analysis to assess changes in cellulose micro/nanofibril structure from fibers subjected to different pre-treatments. Pulp fibers were pre-treated with 5 wt% NaOH for 2 h, 10 wt% NaOH for 1 h, and endoglucanase-type enzymes to improve nanofabrication. After the pre-treatments, the fibers were mechanically fibrillated to produce cellulose micro/nanofibrils, which were made into films to be analyzed. Fibers pre-treated with 5 wt% NaOH produced 59% micro/nanofibrils with an average diameter less than 30 nm, eucalyptus, and 46% of micro/nanofibrils, with the same diameter, for Pincus. However, the enzymatic pre-treatment was the most efficient, resulting in 83% of micro/nanofibrils for eucalyptus and 78% forPinus.This corroborates with the lowest values of the 1.096/2.896ratio and degree of polymerization, indicating chain shortening in cellulose. X-ray diffraction and Raman microspectroscopy crystallinity results presented similar tendencies, with increased crystallinity caused by all pre-treatments, being 5 wt% NaOH for 2 h the highest, with70%, for Eucalyptus and Pinus. Enzymatic pre-treatment has produced the best fibrillation and greater crystallinity. The present work has shown a reliable way of assessing cellulose structure using Raman microspectroscopy.

Characterization of Anthocephalus cadamba and its delignification by kraft pulping

Research

Full-text available

Jul 2021

PULPING 30 TAPPI JOURNAL | MARCH 2010 W orld demand for paper and paperboard is likely to grow by 2.1% annually, reaching an estimated 490 million tons by the year 2020 [1]. Forest cover in India is 67.8 million ha, or 20.6% of the country's surface area. This translates into a per capita forest area of only 0.8 ha/person, one of the lowest in the world [2]. Total fiber consumption for paper and paperboard production in India will nearly be doubled between 2006 and 2016, growing from 7.4 to 13.7 million tons in that time frame. India's total wood fiber deficit is forecast to increase at an annual rate of 11.3% by 2016 [2]. Many fast-growing annual and perennial plants have been identified and studied to assess their suitability for pulp manufacture [3]. Anthocephalus cadamba, commonly known as kadam, is a moderate-sized deciduous tree of the Rubiaceae family. A. cadamba is grown as a soil improver that enhances some physicochemical properties of soil under its canopy when its leaves decompose. A. cadamba upgrades soil by increasing the level of organic carbon, cation exchange capacity , available plant nutrients, and exchangeable bases [4]. To determine optimal mechanical strength for kraft pulping, we examined the anatomical, morphological, and chemical characteristics of A. cadamba and variations in physicochemical characteristics, optimizing various operating parameters including effect of ageing, SEM, °SR. MATERIALS AND METHODS Anatomy and morphology Five logs of 4-year-old A. cadamba were debarked manually. Three samples were taken at 10% (base), 50% (mid-dle), and 90% (top) of their height/length respectively, an approach similar to that followed by Paraskevopoulou [5]. For fiber length determination, small slivers were macer-ated with 10 mL of 67% HNO 3 and boiled at 100±2 °C for 10 min [6]. The slivers were washed and placed in small flask with 50 mL of distilled water. The fiber bundles were separated into individual fibers using a small mixer with a plastic end to avoid breakage. Using a medicine dropper, the macerated fiber suspension was placed on a glass slide [7]. We viewed all fiber samples under a calibrated microscope ; we measured a total of 50 randomly chosen fibers from each sample for a total of 150 fiber measurements. For fiber diameter, lumen diameter, and cell wall thickness determinations, wood cross-sections 25-μm thick were cut on a Leitz base sledge microtome at the same height/length as before. The slices were stained with 1:1 aniline sulfate-glycerin mixture to enhance cell wall visibility, as it retains a characteristic yellowish color. Three derived values-wall fraction, flexibility coefficient, and Runkel ratio [6-9]-were calculated and compared with Eucalyptus teret-icornis and Eucalyptus camaldulensis [10] to assess the potential of A. cadamba for paper production. Scanning electron microscopy (SEM) studies of kraft pulp were conducted using a Leo 435 VP (LEO Electron Microscopy Ltd., Cambridge, England) by taking 2 g pulp for primary fixa-tion using 3% (v/v) glutaraldehyde and 2% (v/v) formalde-hyde (4:1) for 24 hr. The pulp samples were washed three times with double distilled water and treated with alcohol gradients of 30%, 50%, 70%, 80%, 90% and 100% purity, respectively, for dehydration. Samples were kept for 15 min each up to 70% alcohol gradient, and thereafter treated for 30 min each for subsequent alcohol gradients. After treating with 100% alcohol, the pulp samples were air dried and examined under SEM using gold shadowing technique [11]. Electron photomicrographs were taken at 15 kV using detector SE1. ABSTRACT: Anthocephalus cadamba is a fast-growing deciduous tropical hardwood with anatomical, morphological , and chemical characteristics that make it suitable for pulp production. The fibers are short but fiber width, cell wall thickness, and rigidity coefficient of A. cadamba are comparable to those of softwoods such as Pinus kesiya and Picea abies. Due to low lignin and high holocellulose contents, A. cadamba produces high pulp yield at milder cooking conditions. We studied the effect of sulfidity, cooking time, and temperature on pulp yield and kappa number during kraft pulping. The effect of ageing on pulp yield, kappa number, and viscosity indicated that 4-year-old A. cadamba is suitable for pulp production and produces optimal strength properties at 44 Schopper-Riegler degree (°SR). Application: A. cadamba may have potential for pulp and paper production in south Asian countries that have scarcity of wood fibers.

Processing and Properties of Oil Palm Fronds Composite Boards from Elaeis guineensis

Chapter

Full-text available

Jun 2021

Oil palm fronds are one of the biomass residues originating from oil palm plantations. It has great potential to be used as an alternative material for the composite boards industry to reduce dependency on wood-based raw materials. The fronds are obtainable all the year round and in big quantity. The oil palm fronds had been processed as compressed oil palm fronds to form such a potential composite board in this topic. A composite board from compressed oil palm fronds was produced by removing the fronds' leaflets and epidermis. The sample was sliced longitudinally into thin layers and compressed into an identical thickness at about 2 to 3 mm. Pieces of the sample were dry using the air-dried method. They were then mixed with phenol and urea-formaldehyde of resins in the range of 12-15% and compressed again with another layer forming a composite board. Standard outlined by the International Organization for Standardization (ISO) tested for their physical and strength properties of composite board. Found that the physical and strength aspects' properties show that the composite board possessed characteristics at par or equivalent. The composite board from compressed oil palm fronds has good prospects to be used as an alternative to wood. Thus, this characteristics can overcome the shortage in materials supply in the wood-based industry.

Brachiaria brizantha Grass as a Feedstock for Ethanol Production

Article

Full-text available

Apr 2021
BRAZ ARCH BIOL TECHN

Different lignocellulosic biomasses are found worldwide and each country has its own important industrial crop that can be converted into high-value products, such as ethanol. Therefore, evaluation of new biomasses to be used in biorefineries is important to decrease the dependence on non-renewable resources and to guarantee sustainable development. This work evaluated Brachiaria brizantha, a grass commonly used as animal forage, and the standard biomass for 2G-ethanol, sugarcane bagasse. The chemical compositions of both biomasses were determined and different times and temperature of acid pretreatment were tested. Morphological analysis via scanning electron microscopy showed more deconstructed fibers after harsher biomass pretreatments. Simultaneous saccharification and fermentation of pretreated Brachiaria brizantha presented higher efficiency than when using sugarcane bagasse as the carbon source. A biomass conversion of 46 % was achieved when Brachiaria brizantha grass was pretreated with 2% sulfuric acid for 60 minutes. Moreover, fermentation was not impaired by the inhibitors furfural and hydroxymethylfurfural. It was concluded that Brachiaria brizantha is a promising biomass for ethanol production.

Effect of autohydrolysis on hemicellulose extraction and pyrolytic hydrogen production from Eucalyptus urograndis

Article

Full-text available

Sep 2022

Ensuring environmental and social-economic sustainability in the use of materials from lignocellulosic biomass requires their fractionation and valorization of their main components. In this work, we used Eucalyptus urograndis wood to obtain chemicals and energy. The raw material was characterized in chemical terms and then subjected to autohydrolysis under variable operating conditions to optimize the extraction of hemicellulose derivatives relative to cellulose. The kinetics of the pyrolysis process was modeled in terms of activation energy and hydrogen production. Using temperatures in the range of 180–190 °C and treatment times in the range of 15–30 min allowed more than 74.5% of all hemicellulosic components in the raw material to be selectively extracted into the liquid post-hydrolysis phase, more than 90% of all glucan to remain in the solid phase and up to 27.8% of lignin to be removed. The thermal behavior of solid fraction was examined by thermogravimetric analysis, using variable heating rates under a nitrogen atmosphere, and the activation energy can be estimated by using the Flynn-Wall-Ozawa method. Based on the results, the pyrolysis of E. urograndis can be modeled as a first-order reaction. The activation energy (Ea) at a fractional conversion α between 0.3 and 0.7 was 183 to 199 KJ mol−1 for the raw material, whereas that for the solid residue from autohydrolysis ranged from 179 to 186 kJ mol−1 at same fractional conversion when operational temperature in autohydrolysis was upper 185 °C. Based on the results, using temperatures above 180 °C and times of 15 min or longer [i.e., operating at the (0,0) experimental point for the autohydrolysis process] in combination with degrees of conversion from 0.3 to 0.8 reduced the activation energy of the pyrolysis process in relation to the raw material by up to 12% and removed hemicellulose by more 74.5% from it. In parallel, the comparative analysis of the Ea values and the composition of the pyrolysis gas obtained showed a negative relationship between Ea and the amount of hydrogen produced.

Influence of chemical pretreatments on plant fiber cell wall and their implications on the appearance of fiber dislocations

Article

Feb 2020
HOLZFORSCHUNG

The cell wall of plant fibers may contain irregular regions called dislocations. This study evaluated the effect of chemical pretreatment as a mechanochemical dislocation initiator in unbleached and bleached Eucalyptus sp. fibers. Accordingly, bleached and unbleached pulps of eucalyptus were subjected to chemical pretreatments with sodium hydroxide at concentrations of 5% for 2 h, 10% for 1 h and 10% for 2 h or with hydrogen peroxide. The extent of dislocations was evaluated by polarized light microscopy. Based on the observation, an index of dislocations (ID) expressing their ratio of cell wall as per two-dimensional (2D) imaging and their angle relative to the longitudinal direction of the fiber were estimated. Chemical pretreatments increased the ID for bleached and unbleached fibers as well as increased the changes in the curl of bleached and unbleached fibers for chemical pretreatments. Chemical pretreatment extracted the hemicellulose of the fiber cell wall causing some fiber to curl, which in turn generated new dislocations and modifications in the dislocation angles which may be useful for improving the deconstruction process of the cellulose fibers.

Assessment of the self-sustained energy generation of an integrated first and second generation ethanol production from sugarcane through the characterization of the hydrolysis process residues

Article

Nov 2019
ENERG CONVERS MANAGE

This paper compares the physico-chemical characterization of bagasse and sugarcane straw used for second-generation ethanol process and the waste produced in a pilot plant. The bagasse was obtained from conventional ethanol process. The cane straw was pruned in a hammer mill and also sent to the second-generation process. Analysis of the bagasse and the residue after hydrolysis indicated that about 64% of the cellulose and 95% of the hemicellulose in the sample was converted to sugars during hydrolysis. Much of the cellulose therefore remains in the final residue together with the lignin. Results for the available energy from the waste generated during the production of first- and second-generation ethanol indicate considerable potential for thermal power generation. For an integrated plant, with conventional ethanol production, second generation ethanol production and a cogeneration system burning sugarcane straw and process residues, energy self-sufficiency is achieved by using only 36% of the cane straw recovery from the field. In this case, 63 kWh is the surplus electricity generated per ton of cane processed.

Tannin-stabilized silver nanoparticles and citric acid added associated to cellulose nanofibrils: effect on film antimicrobial properties

Article

Full-text available

Oct 2019

The aim of this work was to evaluate the potential of cellulose nanofibrils (CNFs) films treated with commercial solution of Ag nanoparticles stabilized with natural tannin and silane groups in the bacteria growth inhibition. The films were produced with commercial pulps of pine and eucalyptus treated with sodium hydroxide (5% w/v) and calcium hydroxide (10% w/v), respectively. The bacteria selected for the inhibition test were the gram-positive Listeria monocytogenes and gram-negative Salmonella enteriditis. The films performance was investigated by the antimicrobial activity using disc diffusion. In addition, the pulps were evaluated by their chemical composition, water retention index (WRI) and X-ray diffraction (XRD). The content of hemicelluloses in the treated pine pulp (11.32%) was lower in comparison to the found in the treated eucalyptus pulp (14.46%). The XRD diffractogram presented higher crystallinity index for the treated eucalyptus pulp (70%) with a characteristic peak of calcium carbonate. The treated eucalyptus pulp showed higher WRI and viscosity values in relation to the treated pine pulp. Growth inhibitory halos were more expressive when the treatment with both antimicrobial solutions were proceeded in the films produced with pine CNFs with addition of the citric acid. The effect of the nanoparticles stabilized with tannin must be highlighted, mainly on the bacterium S. enteriditis.

INFLUENCE OF VAPORIZATION AND IMPREGNATION OF SILVER NANOPARTICLES ON THE DRYING RATE OF Eucalyptus pellita F. MUELL.

Article

Full-text available

Jul 2019

The aim of this study was to evaluate the effect of vaporization and impregnation of silver nanoparticles on the Eucalyptus pellita wood properties. For that, samples of three radial regions of the wood from three trees were vaporized for 12 and 24 hours and later on, they were immersed in solution of silver nanoparticles with and without application of vacuum (750 mm.Hg). Anatomical, physical and chemical analyzes of the wood were carried out in order to evaluate the effect of the treatments. The drying rate of the wood was determined in moisture bands before and after the fiber saturation point. Generally, the treatments did not modify the anatomical characteristics, permeability, and wood density in the three radial regions; however, the vaporization for 24h reduced the total extractive content in the wood. These results contributed in obtaining gains in the drying rate before and after the fiber saturation point. The effect of impregnation of nanoparticles with vacuum preceded by two periods of vaporization resulted in higher drying rates and the time of 24h stood out, resulting in the best averages among all treatments. The impregnation of nanoparticles had positive effects on the drying rate.

Influence of hemicellulose content of Eucalyptus and Pinus fibers on the grinding process for obtaining cellulose micro/nanofibrils

Article

Full-text available

Jun 2019
HOLZFORSCHUNG

The objective of this study was to verify the effect of the hemicellulose content of commercial bleached pulps on the ease of mechanical fibrillation and on its energy consumption (EC). NaOH in concentrations of 5% with 2 h of reaction, and 10% with 1 and 2 h of reaction, was evaluated for the partial removal of hemicelluloses. Pulp fibrillation was influenced by hemicellulose removal, being less fibrillated when excessive removal occurred (in the range of 4–8.5%). Hemicellulose content in the range of 9–13% increased the water retention value (WRV) and led to nanofibrils with smaller diameter, while a stronger alkali concentration reduced the WRV. X-ray diffraction (XRD) showed that reaction time was a determining factor for the crystallinity of the samples and partial conversion of cellulose I to cellulose II in pretreatments with NaOH 10% (1 and 2 h), and was a factor that may also damage the fibrillation process. Pre-treatment with NaOH 5% for 2 h promoted energy savings for both pulps. This work demonstrated that hemicellulose content has a considerable influence on the mechanical fibrillation and is a key aspect of the balance between efficient fibrillation and the energy required for that.

Autohydrolysis, Pulping, and Bleaching of Eucalyptus urograndis in a Biorefinery Framework

Article

May 2019
BIORESOURCES

Autohydrolysis and kraft pulping were sequentially applied to Eucalyptus urograndis wood to obtain added-value products from hydrolysis liquor. A biorefinery approach was used to bleach the resulting solid phase containing the cellulose pulp with an optimized O-D-(EP)-D bleaching sequence, where O denotes delignification with the sequence D bleaching with chlorine dioxide and EP alkaline extraction with soda and hydrogen peroxide. The pulp was then beaten to obtain paper sheets. The two-stage process yielded pulp with a small Kappa number relative to conventional delignification (4.9 to 13.7 vs 17.1). Using autohydrolysis temperatures of 160 ºC to 170 ºC during 0 min to 15 min made the process selective towards the extraction of hemicelluloses (xylan up to 43.9%). Additionally, the Kappa number and brightness obtained after bleaching with an O-D-EP-D sequence were suitable for preparing dissolving grade pulp. The brightness of the pulp obtained was identical with that of the reference pulp (91.0%) and the Kappa number was smaller (0.2 to 0.6). Beating the pulp for 4500 PFI revolutions produced paper sheets with slightly better tensile strength and tear index than those for sheets from the reference pulp (viz., 90.3 N·m·g-1 and 9.9 mN·m²·g-1 , respectively, versus 89.8 N·m·g-1 and 9.7 mN·m²·g-1 , respectively).

Energetic valorization of sawmill waste through slow pyrolisis

Article

Full-text available

Dec 2018

Brazil is a large producer of sawmill wastes, commonly used to supply boilers and produce energy. In order to reduce unwanted characteristics of the material, thermochemical conversions through carbonization is an alternative. The aim of this study is to characterize the energetic proprieties of raw biomass and pyrolyzed biomass of sawmill residues. In order to analyze the environmental impact in the emission of pyrolysis gases, the behavior of gases during the thermic treatment was determined. Eucalyptus sp. and Pinus sp. residues slow pyrolysis was performed in an electric kiln, whose gases were conducted through a condensable gas recovery system and an online gas analyzer. The charcoal, bio-oil and non-condensable gases yields were estimated. The wood’s and charcoal’s proximate analysis (extractives, lignin, holocellulosis, ash content), higher heating value, equilibrium moisture and density were appraised. The wood’s chemical components were esteemed. Hardwood and softwood’s charcoal presented several differences, especially in yields due to types of lignin. Hardwoods produce a higher amount of acetic acid in slow pyrolysis. This acid was converted, mainly, in carbon dioxide and e a minor extent in methane and carbon monoxide. The gas release was affected by the temperature and wood’s composition. The main gases resulting from the slow pyrolysis of wood are CO2, CO, CH4, H2. The emission of this gases to the atmosphere in addition to increasing the environmental impact caused by the industry is still a waste of energy that could be harnessed more efficiently. Pyrolysis increased the energetic characteristics of sawmill waste. However, in spite of the advantages of carbonization, ways to mitigate the emission of gases emitted in an operational scale should be evaluated.

Addition of corn fiber xylan to eucalyptus and pinus pulp and its effect on pulp bleachability and strength

Article

Full-text available

Aug 2018

Corn fibers are a significant residue of agriculture due to the huge amounts, which has fueled interest in a more rational use of its components, particularly regarding hemicelluloses. The impact of hemicellulose redeposition on printer and writing (P&W) paper grade pulp properties are discussed in this paper. Xylans extracted from corn fibers (16.9 % xylans) by cold caustic extraction (CCE) were added to commercial brown pulps (eucalypt and pine) in the oxygen delignification (O-stage) and further bleached to 90 % ISO brightness. Hemicelluloses deposition occurred at variable degree (up to 7 % on pulp weight). Pulp bleachability was not impaired by xylan deposition for eucalypt and pine pulps. Xylan deposition onto fibers was more efficient in eucalypt pulp than pine. Pulp beatability and strength properties were improved by xylan deposition for P&W paper grades.

Effects of lignin chemistry on oxygen delignification performance

Article

Full-text available

Jul 2018
TAPPI J

The present work focused on characterizing the chemical and structural properties of isolated lignin from six hardwoods and their kraft pulps in an attempt to better understand the relationship between lignin’s chemical properties and resultant oxygen delignification performance. Several hardwood samples were cooked under the same conditions with varying alkali charges to obtain unbleached pulps with kappa numbers between 19 and 20. These pulps were then subjected to an oxygen delignification stage. Both processes were evaluated for pulp quality, residual lignin, and O-stage delignification efficiency. The oxygen delignification stage was carried out under fixed conditions and evaluated with regards to kappa number, which was corrected for hexenuronic acid (HexA) contributions.Results revealed that different hardwood species exhibited differing oxygen delignification efficiencies. A high correlation was found between the O-stage delignification efficiency and the content of phenolic groups in the unbleached lignin, which confirmed that free phenolic groups are the reactive site for molecular oxygen attack. When different hardwood species were compared, the HexA contents were not found to affect O-stage delignification efficiencies.

Avaliação da qualidade e desempenho de clones de eucalipto na produção de celulose

Article

Full-text available

Nov 2017

Comparative study of acid hydrolysis of lignin and polysaccharides in biomasses

Article

Nov 2017
BIORESOURCES

Effects of different acid hydrolysis conditions were studied relative to the chemical transformations of lignin in eucalyptus, sugarcane bagasse, and sugarcane straw, and on the transformations of multiple polysaccharides in eucalyptus. The acid hydrolysis using 12 mol/L sulfuric acid followed by acid hydrolysis using approximately 0.41 mol/L sulfuric acid was used as the reference for the lignin and sugar analysis. During acid hydrolysis, the relative amount of lignin increased with longer reaction times and/or greater acid concentrations for all biomasses. The overestimation of lignin in harsher acidic conditions resulted from the summation of lignocellulosic-derivatives (pseudo-lignin) together with lignin itself. Lignin reactions (dissolution/deposition) for bagasse and straw occurred in a greater extent than for eucalyptus, considering similar conditions of acid hydrolysis. The sugar transformation during acid hydrolysis was also investigated for eucalyptus. The sugar content quantified in eucalyptus decreased as the acid concentration and/or reaction time in the second hydrolysis increased. Glucose, galactose, and mannose were more resistant to harsher acidic conditions than xylose and arabinose. However, the most severe conditions (121 °C, 90 min, and 6.15 mol/L H2SO4) caused complete sugar degradation.

The Effects of Wood Storage on the Chemical Composition and Indigenous Microflora of Eucalyptus species Used in the Pulping Industry

Article

Nov 2017
BIORESOURCES

Lipophilic extractives naturally occurring in wood tend to coalesce during pulping to form pitch deposits, which have particularly undesirable effects on the pulping process and quality of pulp produced. A chemical characterization of different eucalypt species [Eucalyptus nitens, E. grandis, and E. dunnii (of different site qualities)] wood and generated pulp was performed. This study aimed at determining the effects of wood storage at -20°C (for 6 months), by examining their chemical composition and indigenous microflora. Fatty acids were the main lipophilic compounds among E. dunnii (SQ3 and SQ4) and E. grandis wood extractives. The wood of E. nitens posed the least risk for pitch deposit formation, making it the most suitable Eucalyptus species for pulping. Storage of wood chips at -20°C had a similar effect as the traditional method of seasoning (storage of wood outdoors prior to pulping) used for the reduction of lipophilic extractives. A 25 to 44% reduction of total extractives was observed in the raw material after storage. Variations in bacterial and fungal communities were observed after storage, and should be taken into consideration when conducting lab scale trials. If storage of wood chips is necessary for lab testing, it should be retained for a maximum of 3 months at -20°C.

Influence of Elevated Temperatures on the Mechanical Behavior of Jute-Textile-Reinforced Geopolymers

Article

Full-text available

Aug 2017

Geopolymers may present important structural and environmental advantages compared to Portland-cement-based materials. They can achieve high mechanical strength at early ages and exhibit much better thermal durability than Portland-cement-based materials. Geopolymers are brittle materials and an increasing number of studies have been conducted on the incorporation of fibrous reinforcement into these matrices in recent years. Natural fibers appear as a reinforcing group that imply environmental superiority, resulting in improved mechanical behavior. This study evaluates the mechanical behavior of metakaolin-based geopolymers reinforced with jute textile when these are exposed to elevated temperatures. The matrices were activated with a combination of sodium-hydroxide and sodium-silicate solutions. Distinctions in the mixtures were made with the incorporation of different aggregates, i.e. natural quartz sand and chamotte. Direct tensile and compression tests were performed to study the mechanical behavior of the geopolymers when these were exposed to elevated temperatures. In addition, direct tensile tests were conducted on the fibers in different temperature conditions. X-ray diffraction and scanning electron microscopy (SEM) were used to investigate the microstructural changes of the reinforcement. The results indicated superior behavior for the matrices and composites made with the refractory aggregate, indicating a fiber-matrix interaction suitable for this combination at elevated temperatures.

The effect of reaction wood on the properties of eucalyptus kraft pulp - Part II

Article

Full-text available

Sep 2017

The fibers of Eucalyptus wood have characteristics relevant to the Brazilian pulp industry in the production of tissue papers, printing and writing papers, and more recently paper for packaging. The chemical composition and morphology of the fibers of reaction wood are distinct from normal fibers, and can influence both the pulping parameters and the paper properties. The objective of this study was to evaluate the quality of bleached Eucalyptus Kraft pulp, from reaction wood, on paper production. For that, the physicalmechanical and optical properties of bleached eucalyptus pulps produced from trees with straight stem and inclined stem, normal and reaction wood, respectively, were analyzed. The reaction pulp presented physical, mechanical and optical properties superior to the normal pulp, with the exception of tear resistance and apparent specific volume. As such, the reaction pulp obtained higher potential for paper production than the normal pulp. For sanitary purposes, the reaction pulp achieved good water absorption results and also reduced the energy consumption during refining, despite a slight decrease in the tensile and tear index. For the production of printing and writing papers, the reaction pulp had better performance in the optical mechanical resistance properties, with the exception of tear resistance.

Hydrothermal and Acid Pretreatments Improve Ethanol Production from Lignocellulosic Biomasses

Article

Full-text available

May 2017
BIORESOURCES

Hydrothermal and acid pretreatments using different acid charges (1.5%, 3.0%, and 4.5% H2SO4) were proposed for eucalyptus, sugarcane bagasse, and sugarcane straw prior to their bioconversion into ethanol using the semi-simultaneous saccharification and fermentation (SSSF) process. The hydrothermal and acid pretreatments were efficient for hemicelluloses removal from eucalyptus (63 to 96%), bagasse (25 to 98%), and straw (23 to 95%) and to remove a substantial amount of lignin from eucalyptus (10 to 34%) and bagasse (10 to 27%). During pretreatments, pseudo-extractives and pseudo-lignin were generated from biomasses. The SSSF was performed in pretreated biomasses using 24 h presaccharification followed by an additional 10 h of simultaneous saccharification and fermentation (SSF). With hydrothermal pretreatment, the eucalyptus presented the highest ethanol production, but only low values for SSSF parameters were obtained, as follows: ethanol yield (0.017 gethanol/gbiomass), volumetric productivity of ethanol (0.16 g L⁻¹ h⁻¹), and ethanol concentration (1.6 g L⁻¹). On the other hand, using acid pretreatment, the straw (pretreated using 4.5% H2SO4) presented the highest ethanol production among the biomasses, assessed based on ethanol yield (0.056 gethanol/gbiomass), volumetric productivity of ethanol (0.51 g L⁻¹ h⁻¹), and ethanol concentration (5.1 g L⁻¹).

Cellulose pulp produced from bulrush fiber Produção de polpa celulósica a partir das fibras de junco

Article

Full-text available

Jan 2017

Brazil continues to use wood as the principal raw material source for the pulp industry; although, non-wood fibers have been revealed to be a competent substitute to produce paper with different and exceptional properties. Keeping this in focus, this study aimed to assess potential of Schoenoplectus californicus fibers (C. A. Mey.) Soják, commonly identified as bulrush or reed, in cellulosic pulp generation, as an alternative fiber source for the pulp and paper industry. On analyzing the chemical composition of reed fibers, extractives of lignin, carbohydrates, uronic acids and minerals were reported. Physico-chemical characteristics of reed-based cellulosic pulp were estimated including viscosity, hexenuronic acids, etc., as well as anatomical features of length, width, etc. From the chemical analyses of the reed the presence of high concentrations of extractives and silica was clear, making them unfit as raw material for cellulosic pulp production. Pulp kraft pulping process produced brown pulps low in viscosity (34.5m Pa.s) and hexenuronic acid content. Reed is thus classifiable as short-fiber source for pulp and paper industries. Key words: Schoenoplectus californicus, caracterização química, processo kraft. RESUMO: A madeira é a principal fonte de matéria prima utilizada nas indústrias de celulose no Brasil, porém o emprego de fibras não madeireiras pode ser uma alternativa satisfatória para a fabricação de papéis com propriedades diferenciadas e especiais. Nesse sentido, o objetivo desse trabalho foi avaliar o potencial das fibras de Schoenoplectus californicus (C.A. Mey.) Soják, popularmente conhecido como junco, na produção de polpa celulósica, como fonte alternativa de fibras para as indústrias do setor de celulose e papel. Nas fibras do junco foram realizadas análises de composição química, entre elas: teores de extrativos, lignina, carboidratos, ácidos urônicos e minerais. As polpas celulósicas produzidas a partir do junco foram avaliadas no que diz respeito às características físico-químicas (viscosidade, ácidos hexenurônicos, etc.) e anatômicas (comprimento, largura, etc.). As análises químicas demonstraram que as fibras do junco apresentam altos teores de extrativos e sílica, o que as tornam uma matéria prima desfavorável para a produção de polpa celulósica. O processo de polpação kraft do junco resultou em polpas marrons de baixa viscosidade (34,5m Pa.s) e com baixos teores de ácidos hexenurônicos. O junco pode ser classificado como fonte de fibras curtas para as indústrias de celulose e papel. Palavras-chave: Schoenoplectus californicus, caracterização química, processo kraft.

Steam explosion pretreatment used to remove hemicellulose to enhance the production of a eucalyptus organosolv dissolving pulp

Article

Full-text available

May 2017
WOOD SCI TECHNOL

The steam explosion (SE) pretreatment associated with the organosolv process was investigated to produce dissolving pulp from eucalyptus. Prehydrolysis Kraft (PHK) pulping was also done to produce viscose and acetate grade pulps as reference. The organosolv pulps were delignified in two steps with sodium chlorite. Viscose and acetate grade PHK pulps were bleached by OD0(EH)D1P and OD0(EP)D1PCCE sequences, respectively. Dilute acid-catalyzed (with acid addition) SE pretreatment dissolved more xylan than auto-catalyzed (no acid addition) SE pretreatment. Steam-exploded unbleached organosolv pulps showed lower residual lignin content and screened yield than unbleached organosolv pulps without SE pretreatment. Steam explosion pretreatment helped to decrease lignin content and damaged fiber length of unbleached organosolv pulps. The 1.0% H2SO4 organosolv pulp (organosolv dissolving pulp at bioconversion conditions) showed the highest reactivity. Even showing low viscosity for some applications, in general, the organosolv dissolving pulps produced in this study can be used for making lyocell fibers.

Assessment of alkaline pretreatment for the production of bioethanol from eucalyptus, sugarcane bagasse and sugarcane straw

Article

Dec 2016
IND CROP PROD

The impact of alkaline pretreatment at different alkaline charges (5%, 10% and 15% NaOH w/w, on dry basis) on the chemical composition of eucalyptus, sugarcane bagasse and straw were compared with the subsequent bioconversion into ethanol, using semi-simultaneous saccharification and fermentation (SSSF). By increasing alkaline charge in pretreatments, substantial amount of lignin, hemicelluloses and cellulose were fractionated. The chemical composition of biomasses was expressed based on the complete mass balance. The chemical transformation of biomasses during pretreatments was assessed by comparing the chemical composition of pretreated biomasses and their untreated counterparts. Pretreatments promoted delignification in the range of 11%–51% for eucalyptus, 22%–90% for bagasse, and 60%–99% for straw for the alkaline charges in the range of 5%–15% (NaOH w/w). The removal of lignin from bagasse and straw was higher than that from eucalyptus, which was due to the combined effect of higher frequency of both, the free phenolic groups and the ester bonds in grass lignin that made the lignin solubility escalate in alkaline conditions. It was also observed that bagasse had a removal by 37%–45% hemicelluloses and 0.8%–11% cellulose. For straw, higher amount of carbohydrates was removed, in the range of 55%–66% hemicelluloses and 19%–36% cellulose. Fragments of lignin and carbohydrates were converted into new structures called “pseudo-extractives” in eucalyptus during pretreatments. Pseudo-extractives and native extractives were quantified together, thus increasing the total extractives contents by 3.3 (5% NaOH), 3.5 (10% NaOH) and 2.9 (15% NaOH) times, in line with the original raw materials. Maximum ethanol yield and maximum volumetric productivity of ethanol were achieved for eucalyptus pretreated using 10% NaOH, bagasse pretreated using 15% NaOH and straw pretreated using 5% NaOH. At the optimal pretreatment condition, just about 51% glucose was released from pretreated bagasse. Sugarcane bagasse presented the highest values for the respective parameters, namely: 8.8 g L⁻¹ ethanol concentration, 0.101 gethanol/gbiomass ethanol yield and 0.88 g L⁻¹ h⁻¹ volumetric productivity of ethanol. Alkaline charge proved to be an important control variable for alkaline pretreatments, with determinant effect on chemical transformations of biomasses and result on ethanol production.

Effects of Xylan in Eucalyptus pulp production

Article

Full-text available

Jan 2016

The search for a better use of wood in the pulp industry has fuelled interest in a more rational use of its components, particularly xylans. The impact of xylans removal and of xylans redeposition on pulp properties for tissue and P&W paper grades are discussed in this paper. Kraft pulp (15.6% xylans) treatment with 10-70 g.L⁻¹ NaOH resulted in pulps of 14.5-5.9% xylans. The treatments decreased pulp lignin and HexA contents and caused significant positive impact on subsequent oxygen delignification and ECF bleaching. Xylan removal decreased pulp beatability, water retention value and tensile index but increased drainability, water absorption capacity, capillarity Klemm and bulk. Overall, xylan depleted pulps showed almost ideal properties for tissue paper grade pulps. In a second step of the research, xylans extracted from unbleached (BXL) and bleached eucalyptus pulps (WXL) by cold caustic extraction (CCE) were added to a commercial brown pulp in the oxygen delignification (O-stage) and further bleached. Xylans deposition occurred at variable degree (up to 7% on pulp weight) depending upon the O-stage reaction pH. Pulp bleachability was not impaired by WXL xylan deposition but slightly negatively affected by BXL xylans. Pulp beatability was improved by xylan deposition. The deposited xylans were quite stable across bleaching and beating, with the WXL xylans being more stable than the BXL ones. At low energy consumption, the deposited xylans improved pulp physical and mechanical properties. Xylans extraction by CCE with subsequent deposition onto pulp in the O-stage proved attractive for manufacturing high xylan P&W paper grades.

EFEITOS DA XILANA NA PRODUÇÃO DE CELULOSE DE EUCALIPTO

Article

Full-text available

Jun 2016
CERNE

The search for a better use of wood in the pulp industry has fuelled interest in a more rational use of its components, particularly xylans. The impact of xylans removal and of xylans redeposition on pulp properties for tissue and P&W paper grades are discussed in this paper. Kraft pulp (15.6% xylans) treatment with 10-70 g.L-1 NaOH resulted in pulps of 14.5-5.9% xylans. The treatments decreased pulp lignin and HexA contents and caused significant positive impact on subsequent oxygen delignification and ECF bleaching. Xylan removal decreased pulp beatability, water retention value and tensile index but increased drainability, water absorption capacity, capillarity Klemm and bulk. Overall, xylan depleted pulps showed almost ideal properties for tissue paper grade pulps. In a second step of the research, xylans extracted from unbleached (BXL) and bleached eucalyptus pulps (WXL) by cold caustic extraction (CCE) were added to a commercial brown pulp in the oxygen delignification (O-stage) and further bleached. Xylans deposition occurred at variable degree (up to 7% on pulp weight) depending upon the O-stage reaction pH. Pulp bleachability was not impaired by WXL xylan deposition but slightly negatively affected by BXL xylans. Pulp beatability was improved by xylan deposition. The deposited xylans were quite stable across bleaching and beating, with the WXL xylans being more stable than the BXL ones. At low energy consumption, the deposited xylans improved pulp physical and mechanical properties. Xylans extraction by CCE with subsequent deposition onto pulp in the O-stage proved attractive for manufacturing high xylan P&W paper grades.

Cold alkaline extraction as a pretreatment for bioethanol production from eucalyptus, sugarcane bagasse and sugarcane straw

Article

Jul 2016
ENERG CONVERS MANAGE

Effect of properties chemical and siringil/guaiacil relation wood clones of eucalyptus in the production of charcoal

Article

Full-text available

Apr 2016

The objective of this study was to determine the influence of the chemical properties (elemental composition, levels of extractives, lignin total and holocellulose) and the syringyl/guaiacyl, wood of different Eucalyptus genetic materials in the production of charcoal. It was used in the study four hybrid clones, at age of 7 years, 6 trees per clone, totaling 24 sampling units. There was significant difference, at 5% significance, between treatments for elemental composition, levels of extractives, lignin total and holocellulose and the wood syringyl/guaiacyl, as well as for gravimetric yields in charcoal, condensable gases and non-condensable gases, levels of fixed carbon and volatiles, and for the higher calorific value of charcoal. For the ash content and relative apparent density of charcoal were not observed significant differences at the same level of significance. Concluded that there is variability in the wood quality of four evaluated genetic materials, having the same, distinct correlations, thus the yield and the quality of charcoal. All genetic material presented satisfactorily gravimetric yield in charcoal and quality. The woods of clones with low syringyl/guaiacyl ratio showed an increase in yield in charcoal. The chemical composition of woods from the four clones, in general, showed no significant correlations, the 5% significance level, at the yield and quality of charcoal. © 2016, Universidade Federal de Santa Maria. All Rights Reserved.

INFLUÊNCIA DAS PROPRIEDADES QUÍMICAS E DA RELAÇÃO SIRINGIL/GUAIACIL DA MADEIRA DE EUCALIPTO NA PRODUÇÃO DE CARVÃO VEGETAL EFFECT OF PROPERTIES CHEMICAL AND SIRINGIL/GUAIACIL RELATION WOOD CLONES OF EUCALYPTUS IN THE PRODUCTION OF CHARCOAL

Article

Full-text available

Jun 2016
CIENC FLOREST

The objective of this study was to determine the influence of the chemical properties (elemental composition, levels of extractives, lignin total and holocellulose) and the syringyl/guaiacyl, wood of different Eucalyptus genetic materials in the production of charcoal. It was used in the study four hybrid clones, at age of 7 years, 6 trees per clone, totaling 24 sampling units. There was significant difference, at 5% significance, between treatments for elemental composition, levels of extractives, lignin total and holocellulose and the wood syringyl/guaiacyl, as well as for gravimetric yields in charcoal, condensable gases and non-condensable gases, levels of fixed carbon and volatiles, and for the higher calorific value of charcoal. For the ash content and relative apparent density of charcoal were not observed significant differences at the same level of significance. Concluded that there is variability in the wood quality of four evaluated genetic materials, having the same, distinct correlations, thus the yield and the quality of charcoal. All genetic material presented satisfactorily gravimetric yield in charcoal and quality. The woods of clones with low syringyl/guaiacyl ratio showed an increase in yield in charcoal. The chemical composition of woods from the four clones, in general, showed no significant correlations, the 5% significance level, at the yield and quality of charcoal.

Polpação kraft convencional e modificada para madeiras de Eucalyptus grandis e híbrido (E.grandis x E.urophylla)

Conference Paper

Full-text available

Oct 2002

The objective of the present research was the evaluation of the performance of conventional and modified cooking process for the wood of Eucalyptus grandis and of hybrid (Eucalyptus grandis x Eucalyptus urophylla), considering the process parameters and wood quality aspects; as process modification were considered the alkali charge and the use of anthraquinone. The pulping processes were performed considering 3 different delignification levels (kappa numbers 14, 16 and 18), for each cooking the yield and pulp kappa number, viscosity and carbohydrate composition were determined for the pulps and the black liquors analyzed in terms of solids content and residual alkali. The results showed a difference between E. grandis and of the hybrid of E. grandis x E. urophylla in terms chemical composition and pulp yield with better figures obtained for E. grandis. The better performance of the E. grandis in terms of pulping (higher yield, lower kappa number and chemical consumption) is related to the lower content of lignin and extractives when compared to the wood of the hybrid of E. grandis x E. urophylla. In terms of pulping, the differences observed, were related to the raw material, pulping process, anthraquinone and delignification level. The hybrid of E. grandis x E. urophylla required a higher alkali charge for a targeted delignification level, when compared to E. grandis. The modified processes, for both raw materials required a higher initial alkali charge, when compared to conventional cooking, but the alkali consumption was lower, showing a beneficial aspect of the modified cookings. The use of anthraquinone, for both raw materials, pulping process and delignification levels, lead to an increase in yield and a reduction in alkali charge. The differences in raw-materials, pulping process, use of anthraquinone and delignification levels resulted in pulps with different carbohydrate compositions; with those results were possible to define a correlation between carbohydrate composition and yield; those results can be considered as tools for yield determination in industrial scale.

The use of enzymatic pre-treatment to facilitate and reduce the energy consumption of unbleached cellulose micro/nanofibrils production from Eucalyptus spp. and Pinus spp. kraft pulps

Article

Full-text available

Feb 2023
EUR J WOOD WOOD PROD

Cellulose micro/nanofibrils have gained prominence due to their structure, which is composed of crystalline and amorphous regions, and varying extraction approaches can generate different micro/nanofibrils morphology and structure. This work aimed to evaluate the application of endoglucanase enzyme in different types of unbleached cellulosic pulps as a pre-treatment to reduce energy consumption in mechanical fibrillation. Chemical, morphological and mechanical properties of fibers and micro/nanofibrils pre-treated with and without enzyme were evaluated. Kraft pulps from Eucalyptus spp. and Pinus spp. were dispersed in water (3% w/w) and pre-treated with enzyme A, enzyme B, and without enzyme, as a control. The pulps were rinsed, resuspended (2% w/w,) and submitted to mechanical extraction by 5 cycles through a grinder, recording the energy consumption. Results indicated that the chemical and compositional characteristics of all pulps have not been affected by the enzymatic pre-treatment. There was an increase in water stability and a decrease in the mean diameter of the micro/nanofibrils. The tensile strength of the films also increased with increasing grinding cycles. All kraft pulps pre-treated with enzymes A and B showed a decrease in energy consumption, with up to 44% of energy savings in Eucalyptus spp. kraft pulp while 67% for Pinus spp. Thus, the enzymatic pre-treatment proved to be a sustainable alternative for cellulose nanofibril extraction, generating well-fibrillated micro/nanofibrils at low energy consumption.

Structural and chemical characterization of lignin and hemicellulose isolated from corn fibers toward agroindustrial residue valorization

Article

Full-text available

Aug 2022
CELLULOSE

Corn fiber (CF) is an agroindustrial residue obtained from starch or corn syrup. Currently, there has been increasing research interest in lignocellulosic materials from these residual materials. Consequently, this paper is a novel approach that complements the structural and chemical characterizations already published in the literature for CF. In this study, isolation, chemical composition and characterization was conducted of hemicellulose by means of ¹H NMR and FTIR-ATR and Klason lignin by means of acid soluble lignin (ASL) and acid insoluble lignin (AIL) determination using UV spectrophotometry and Py–GC‒MS. Hemicellulose was obtained after aqueous extraction, lipid removal, delignification and alkaline extraction. The isolated hemicellulose from CF confirmed the presence of arabinoxylan, which was similar to the results reported in the literature. The CF contained 8.0% and 4.0% ASL and AIL, respectively. Regarding lignin, the study identified more than 47 primary pyrolysis products for ASL, with 17%, 20% and 59% relative molar abundance for lignin, carbohydrates, and other products, respectively, and 39 primary pyrolysis products with 44% and 7% relative molar abundance for lignin and carbohydrates, respectively. The main products derived from lignin were phenol, 4-methylphenol, guaiacol, 4-vinilguaiacol, syringol and syringylaldehyde. The peaks of lignin derivatives indicated that the Klason method is effective for lignin isolation, and the Py–GC‒MS technique allowed for the identification of the presence of residual lignin in AIL and ASL from CF. In this context, lignocellulosic components of CF are chemically suitable for use as raw materials to transform biomass into high value-added products. Graphical abstract

ASSESSMENT OF INDUSTRIAL PERFORMANCE FOR MARKET PULP PRODUCTION BETWEEN EUCALYPT AND Corymbia HYBRIDS CLONES

Article

Full-text available

Aug 2022

The search for novel biomasses for uses as alternative fiber sources, similar to Eucalyptus spp. biomass, holds great value and potential for commercial-scale application. This study aims to present the hybrid clones of Corymbia spp. developed by Aperam BioEnergia as potential substitutes for Eucalyptus wood in the market pulp industry. By performing modified kraft pulping and chemical characterization analyses, it was possible to compare the biomass of Eucalyptus spp. with that of Corymbia spp. Comparisons were made by analyzing their respective pulp average growth rate (PAGR) and specific wood consumption (SWC), estimated using a kappa number of 19 ± 1. The results showed that one of the hybrid clones (Corymbia citriodora × Corymbia torelliana - ID 4) had highest PAGR#k19, and lowest SWC than other samples. Clone ID 4 showed lowest value of SWC since, simultaneously presented a higher value of wood basic density and screened yield. Consequently, in agreement with its best results, clone ID 4 had the highest-ranking score, calculated as the PAGR/SWC ratio. This genetic material also showed one of the lowest total lignin content, consequently the highest screening yield. Besides Clone ID 4 showed significantly highest xylan content, among wood samples assessed in this work. For that reason, the ID 4 was the highest-ranked, proving to be an excellent high-performance alternative for forest-industry interface parameters. Keywords: Eucalyptus vs Corymbia; Modified kraft pulping; PAGR

Recovering Wood Waste to Produce Briquettes Enriched with Commercial Kraft Lignin

Article

Full-text available

Jan 2021

EFFECT OF THE LOG STORAGE OF Pinus taeda L. ON THE QUALITY OF KRAFT PULP

Article

Sep 2020

In pulp production, wood in logs is stored for periods that can range from a few weeks to several months. During storage, changes in the wood properties that affect the pulping process and the quality of the pulp may occur. The objective of this study was to determine the ideal timing of wood storage in logs by evaluating the variations (a) in the chemical properties of wood (b) in the parameters of the pulping process and (c) the quality of the Pinus taeda pulp. Logs were stored in an industrial courtyard for 30, 60, 90, 120 and 150 days. In each storage period, the physical and chemical properties of the wood, the cooking parameters, and the properties of the pulp were analyzed. The chemical properties of wood varied throughout storage, but only the solubility in sodium hydroxide showed a positive and significant correlation with storage time. In pulping, the yield and tailings had an inversely proportional correlation with the storage time, while the organic and total solids content had a positive correlation. As for cellulose quality, arabinan and soluble lignin contents did not vary during storage. The mannan content had a positive and significant correlation with the storage time. Taking into account all the variables analyzed, the storage time of P. taeda logs should be up to 30 days.

High-yield cellulase and LiP production after SSF of agricultural wastes by Pleurotus ostreatus using different surfactants

Article

Nov 2019

White rot fungi are well known for their ability to degrade the structures of the plant cell walls and to produce of a wide range of extracellular enzymes using lignocellulosic biomass as substrate. In an attempt to reduce the costs and obtain high-yield of lignocellulolytic enzymes such as cellulases and lignin peroxidase, their production has been studied by solid-state fermentation using low-cost agroindustrial residues as carbon sources and surfactants. In this context, this work aimed the produce cellulases and lignin peroxidase from the fungus Pleurotus ostreatus PLO 9 using banana pseudostem, jatropha and coconut fiber as the substrates supplemented with the surfactants tween 80, sodium dodecyl sulfate and glycerol. The results showed the maximum lignin peroxidase activity was obtained after 15 days of fermentation using jatropha supplemented with sodium dodecyl sulfate (49916 ± 541 U g⁻¹ of substrate). The highest cellulase production was reached after 5 days of fermentation using banana pseudostem supplemented with glycerol as the substrate (19.5 ± 0.2 FPU g⁻¹ of substrate). The results indicate that it was possible to reach significant activities of cellulase and LiP using the white rot Pleurotus ostreatus after solid state fermentation of lignocellulosic biomass using surfactants as exogenous inducers.

UTILIZAÇÃO DO BAMBU COMO MATÉRIA-PRIMA NA OBTENÇÃO DE POLPA CELULÓSICA VOLTADA À FABRICAÇÃO DE PAPEL DE EMBALAGEM SACKRAFT

Article

Full-text available

Oct 2018

A tendência de aumento no custo da madeira nos últimos anos tem estimulado a busca por matérias-primas alternativas, onde o bambu surge como potencial biomassa. Sendo assim, esse estudo objetiva analisar a aplicabilidade do bambu da espécie Bambusa vulgaris para a produção de polpa celulósica kraft voltada à produção de papel de embalagem sackraft. Realizou-se a caracterização química e morfológica das fibras do bambu e polpação kraft com bambu livre de amido. O bambu apresentou teores de holocelulose (63,4%) e lignina (23,2%) favoráveis à sua utilização em polpação kraft. O rendimento de polpação (54,9%) foi mais elevado que o obtido em coníferas. As dimensões das fibras do bambu favorecem as características físico-mecânicas necessárias para a produção de papéis do tipo sackraft. Conclui-se, portanto, ser possível utilizar o bambu em substituição à madeira na aplicação sugerida.

Totora ( Schoenoplectus californicus (C.A. Mey.) Soják) and its potential as a construction material

Article

Feb 2018
IND CROP PROD

Totora is an emergent macrophyte with properties and historical uses supporting its potential use in contemporary construction and for reducing pressure on conventional forest plantations by diversifying the sources of biomass-based materials. Recent advances in the wood construction field have demonstrated the feasibility and advantages of using wood-based materials in tall building structures and other massive constructive uses, which could lead to a net reduction in CO₂eq emissions from the construction sector by replacing high-energy consuming materials such as concrete or steel with wood and biomass-based materials. Among these biomass-based materials are non-timber forest products. This category includes plants that can provide important contributions to the construction sector by diversifying the sources of biomass-based materials. One of these plants is totora (Schoenoplectus californicus (C.A. Mey.) Soják). Totora is a bulrush that grows in lakes and marshes in the Americas, from California to Chile, and some of the Pacific islands. This bulrush has been used by many cultures as medicine, food, forage, and material for building houses, boats, and different handicrafts. Although several people still use totora to make their handicrafts and rafts, the most important current examples of the use of totora are the floating islands of the Uros in Lake Titicaca. The Uros people have developed traditional techniques for building their homes, boats, and even the artificial islands where they live, with methods based almost exclusively on the totora culms. The studies and experimentation conducted on this plant have underscored its fast growth capacity, high yield values, anatomical and physical properties, and potential environmental benefits. This review aims to analyze the available data on this material regarding its potential for construction, which is intended to foster its research and development as an alternative source of a biomass-based building material.

Carbohydrate composition in Eucalyptus wood and pulps – Comparison between Py-GC/MS and acid hydrolysis

Article

Nov 2017
J ANAL APPL PYROL

In analytical pyrolysis, carbohydrates are degraded into stable anhydrosugars, which are analyzed by GC/MS. The benefit of Py-GC/MS is that fiber composition including carbohydrates, lignin and its S/G ratio can be determined simultaneously from fiber-based materials without need of extensive pretreatment, contrary to the traditional method. In this study, the relative carbohydrate composition of various Eucalyptus species was determined by Py-GC/MS. In addition, pulps produced from the same species by soda-AQ and soda-O2 processes were analyzed similarly. The results were compared with those obtained by acid hydrolysis followed by HPLC. This comparison showed that the relative carbohydrate composition determined by Py-GC/MS for the wood samples differed from the values obtained by acid hydrolysis. Significantly better correlation between the two methods was observed for the pulp samples cooked to varying kappa number levels. Fractionated pyrolysis was applied in order to find explanation to the observed difference in the degradation behavior of carbohydrates in wood and pulp samples. Due to the close association of lignin and carbohydrates, the thermal behavior of lignin was followed as well. The results showed that the thermal behavior of xylan and cellulose differed in the wood samples, but were almost equal in the pulp samples. Thermal degradation of xylan was similar with lignin in both sample types. Similar thermal behavior between the components is a prerequisite for reliable Py-GC/MS analysis. Therefore, this method cannot be recommended for the comparison of carbohydrate compositions between different wood raw materials. However, it is applicable to pulp samples and may find application in research for profiling carbohydrate compositional changes with processing methods: and conditions.

The effect of reaction wood on bleached eucalypt kraft pulp production - Part I

Article

Full-text available

Sep 2017

Wood quality is the key element for the production of high-performance, high-bleachability cellulose pulp. The presence of reaction wood may have significant impact on its various applications. This study investigated the effect of reaction wood on the production of bleached eucalypt kraft pulp. Normal and reaction wood eucalypt chips were compared regarding their indepth chemical composition and kraft pulping. The Kraft pulps derived from normal and reaction wood were compared for bleachability, chemistry and quality. Reaction wood requires less effective alkali to reach a given delignification degree, but retains less yield in relation to normal wood. At the kappa number 18±0.5, the brown pulp derived from reaction wood contains less cellulose and hemicelluloses, more HexA and lower viscosity in relation to that of normal wood. Although the pulp derived from reaction wood showed slightly lower efficiency in the oxygen delignification stage it performed better across ECF bleaching, reaching a brightness 1% higher at fixed chemical charge. The final bleached pulp derived from reaction wood showed lower viscosity and higher brightness reversion in relation to normal wood. Thus, reaction wood chips can be used for production of bleached grade pulps without major concern, if combined in small fractions to normal wood.

Production of printing and writing paper grade pulp from elephant grass

Article

Full-text available

Sep 2016
CERNE

The main goal of this study was to characterize chemically and morphologically elephant grass (Pennisetum purpureum), and evaluate the potential of its fibers for production of printing and writing paper grade pulp. The elephant grass was chemically and morphologically characterized and cooked by the soda process to two different degrees of delignification (kappa 17.5 and 10.6). The resulting pulps were fully bleached by the O-D*-(EP)-D sequence and characterized for their beatability, drainability and physical-mechanical properties. The lignin content (20.2%) was low, indicating that this grass should be easier to pulp. The morphological analyses of the elephant grass indicated a short fiber material, similar to hardwoods. The soda pulp from elephant grass cooked to kappa number 17.5 presented higher screened yield than 10.6 kappa pulp, with alkali demands of 15.0% and 20.0%, respectively. The total active chlorine required by the 17.5 and 10.6 kappa pulps, were 42.1 and 35.1 kg/odt pulp, respectively, to achieve an ISO brightness of approximately 90.0%. The bleached soda pulps cooked to 17.5 and 10.6 kappa number showed similar refinability and resistance to drainage, but the tensile and burst index were highest for the 17.5 kappa pulp at beating energy consumptions in the range of 0-6 Wh. It was concluded that both 10.6 and 17.5 kappa pulps from elephant grass are suitable for the production of printing and writing paper grade pulps, but the highest kappa 17.5 pulp is more economically attractive given its highest pulping yield, despite the significantly increased of chemical demand for bleaching A produção de papel para impressão e escrita Grau de celulose a partir de capim-elefante.

Effect of Lignin Carbohydrate Complexes of Hardwood Hybrids on the Kraft Pulping Process

Article

Oct 2016

Lignin-carbohydrates complexes influence many chemical properties in the wood, such as difficult-to-remove lignin from Kraft pulps at the end of pulping due to the occurrence of lignin carbohydrates bonds. Therefore, this study aimed to study the influence of lignin-carbohydrate complexes on eucalyptus Kraft pulping. Spectroscopic techniques (¹³C NMR and HSQC-2D) were applied for the determination and quantification of lignin-carbohydrate complex (LCC) structures, and then evaluated the effect of LCC on Kraft pulping of eucalyptus hybrids. The analytical tools allowed the identification and quantification of the benzyl ether, γ-ester, and phenyl glucoside linkages of the lignin-carbohydrate complexes in eucalyptus hybrid wood. The glycosidic phenyl and γ-ester linkages are, respectively, more and less significant from the quantitative point of view. Analysis of ¹³C NMR of the samples showed that the eucalyptus hybrid GxGL contained high β-O-4 linkages content and also higher pulping yield than the other samples, suggesting that the linkages between lignin are more important than LCC linkages in pulping.

Chemical analysis of polysaccharides in plantation eucalypt woods and pulps

Abstract

No full-text available

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