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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.

The characteristics of cellulose micro/nanofibrils (MFC/CNF) can be improved with pre-treatments of the original fibers. The present work is proposed to study pre-treatment with sodium silicate (Na2SiO3) on bleached fibers of Eucalyptus sp. (EUC) and Pinus sp. (PIN) and its effects on the quality index of MFC/CNF. Particle homogeneity, turbidity, and microstructure of the suspensions were evaluated. Similarly, the physical-mechanical, and barrier properties of the films were studied. With the results obtained for suspensions and films, the quality index (QI) was MFC/CNF calculated. The smallest particle dimension was observed for MFC/CNF of Pinus sp. with 10 % of Na2SiO3, as well as the lowest turbidity (∼350 NTU) was obtained for MFC/CNF of Pinus sp. with 5 % of Na2SiO3. The pre-treatments reduced the transparency of the films by ∼25 % for EUC and ∼20 % for PIN. The films presented a suitable barrier to UVC radiation, water vapor, and oil. The tensile strength of EUC and PIN films was increased by 20 % using 10 % of Na2SiO3. The same concentration of Na2SiO3 provided QI 70 for EUC MFC/CNF. The Na2SiO3 was efficient to obtain the MFC/CNF with interesting properties and suitable to generate films with parameters required for packaging.

This study aimed to evaluate the properties of cellulose nanofibers (CNFs) with different hemicellulose contents and cellulose II polymorphs. A link was found between these polysaccharides and the properties of CNFs. A decrease in crystallinity (from 69 to 63%) and changes in the crystalline structure of cellulose subjected to an alkaline environment were observed, promoting the partial conversion of cellulose I to cellulose II (from 2 to 42%) and preventing CNFs production at NaOH concentrations higher than 5%. Most treatments showed pseudoplastic fluid behavior, except for the 10% NaOH treatment over 2 h, which showed Newtonian fluid behavior. The quality index of the reference CNFs (TEMPO-oxidized) was the highest (80 ± 3), followed by that of the 5% NaOH-treated (68 ± 3 and 22% energy savings compared to the untreated sample), and the untreated (63 ± 3) samples; and the 10% NaOH treatments had quality indices of 51 ± 3 and 32 ± 1, respectively.

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 nanofibrilation. 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 average diameter less than 30 nm, for Eucalyptus, and 46% of micro/nanofibrils, with the same diameter, for Pinus. However, the enzymatic pre-treatment was the most efficient, resulting in 83% of micro/nanofibrils for Eucalyptus and 78% for Pinus. This corroborates with the lowest values of the 1.096/2.896 ratio 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, with 70%, 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.

Dislocations are weak and discontinuous areas of plant cell walls. This study aims to evaluate the cellulase-mediated enzymatic pretreatment as a mechanical-chemical initiator of dislocations in unbleached and bleached fibers of commercial Eucalyptus kraft pulp, comparing both before and after the formation of micro/nanofibers in the mechanical process, in addition to evaluating the dislocations themselves. Four enzyme complexes were evaluated, of which three were endoglucanase (A, B and C) and one was a mixture of endoglucanase and exoglucanase (D), in addition to a control pretreatment. During the mechanical treatment of the fibers pretreated with enzyme B, samples were collected at pass/cycles 0, 5, 10, 15, 20, 25 and 30 in the mechanical fibrillator. The dislocations were evaluated using a polarized light microscope to analyze the index of dislocations (ID), dislocation angle and curvature index, while the crystallinity was analyzed by Raman spectroscopy. For bleached fibers, a reduction in the ID occurred with enzyme C and an increase with enzyme B, while for unbleached fibers, the ID did not change significantly. During the mechanical treatment, the enzyme did not cause a reduction in the fiber length (FL) but allowed a significant increase in the ID up to 20 passages for all pretreated fibers, with and without enzymes. The dislocation angle decreased with the enzymatic action and with the curvature index. The results show that the enzymatic pretreatment can affect the integrity of the fibers, increasing the number of dislocations and amorphous regions and decreasing the length of the cellulose chain.

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.

Lignin-cellulose nanofibrils (LCNF) are of attracting an increasing interest due to the benefits of maintaining the lignin in the nanomaterial composition. The production of LCNF requires considerable energy consumption, which has been suppressed employing pretreatment of biomass, in which it highlights those that employ enzymes that have the advantage of being more environmentally friendly. Some negative aspects of the presence of lignin in the fiber to obtain cellulose nanofibrils is that it can hinder the delamination of the cell wall and act as a physical barrier to the action of cellulase enzymes. This study aimed to evaluate the impact of a combined enzymatic pretreatment of laccase and endoglucanase for high content lignin LCNF production. The morphological and chemical properties, visual aspect and stability, crystallinity, mechanical properties, rheology, barrier properties and quality index were used to characterize the LCNF. The laccase loading used was efficient in modifying the lignin to facilitate the action of the endoglucanase on cellulose without causing the removal of this macromolecule. This pretreatment improved the quality of LCNF (61 ± 3 to 71 ± 2 points) with an energy saving of 42% and, therefore, this pretreatment could be suitable for industrial production for a variety of applications.

This work proposes to evaluate the effect of spray-coating in papers using eco-friendly cellulose nanofibrils (CNFs) and nanoclay (NC) on mechanical and barrier properties for application as reinforced bags. Sack kraft papers of 60 g m-² (C60) were coated with CNFs + CNFs/NC in 4 layers (L5), 40 g m-² of CNFs + CNFs/NC in 3 layers (L4), 30 g m-² with CNFs/NC in 2 layers (L3) and 10 g m-² of CNFs in 1 layer (L2), and compared to uncoated sack kraft papers with basis weight of 60 g m-² (C60), 80 g m-² (C80) and 120 g m-² (C120). The coated papers L2; L3; L4 and L5 obtained a decrease in water vapor transmission rate (WVTR) of 3.5%; 17%; 14% and 14%, respectively, when compared to C60. Comparing L2 and L3, CNF layer induced lower contact angles on the coated paper than CNF/NC layer. When compared coated papers with C120, it was observed an increase of around 66% in tensile strength for L2, around 44% for L3, and decrease of ~ 18% for L5 coated papers. L4 achieved the same tensile strength (when divided by basis weight) than C120. L2 and L3 coated papers led to the highest values of Young’s modulus, with increase of 56% and 38%, respectively, when compared to C60. Spray-coating in the present conditions improved the mechanical and barrier properties of the coated papers, being a possible alternative to produce papers with lower basis weight and using renewable raw materials.

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.

Commercializing dried microfibrillated cellulose (MFC) has always been a challenge mainly due to the tendency of MFC to aggregate. In this study MFC samples were submitted to drying/redispersion cycles at different temperatures. Morphology, crystallinity and mechanical performance of films were analyzed throughout the cycles. Microscopy images, particle size and stability in water showed that aggregation happens more severely with 5 drying/redispersion cycles and at drying temperatures of 75 and 100 °C. Particles once-dried at 20 °C formed the same size and web-like structure as the MFC-control. Crystallinity and crystallite sizes increased with drying/redispersion cycles especially when dried at 75 and 100 °C, however drying/redispersion cycles also led to a reduction in mechanical performance due to aggregation. While oven-drying is not the most suitable method, milder action at room temperature once-drying led to suspension stability in water, morphology and mechanical properties close to never-dried MFC, which makes this treatment a feasible option to maintain cellulose quality.

Wind may damage eucalyptus trees, especially 24 months after planting, which can reduce wood fiber quality and hinder pulp production. The objective of this study was to evaluate the use of these materials in mixtures with wood from seven-year-old trees to produce pulp. Bleached pulp was produced using 100, 95, 85, 75 and 0% wood from seven-year-old eucalyptus trees, related to cutting age. Wood from two-year-old trees, when trees are most susceptible to damage by wind, completed each treatment. A 5 cm thick disc was taken from breast height (1.3m) on each tree for anatomical and ultrastructural characterization. The seven-year-old wood had lower vessel frequency and fibers with a longer length, higher cell wall fraction, higher modulus of elasticity and hardness, and a lower microfibril angle. Pulp refining decreased the opacity and specific volume, increased air resistance and improved mechanical properties. The addition of two-year-old wood to produce pulp reduced the mechanical properties and opacity, and increased the air resistance of the paper. The proportion of two-year-old wood that can be used in pulp production varied with the clone, parameter, and refining level. However, the pulp produced with 5% wood from two-year-old trees and 95% wood from seven-year-old trees was similar to that with 100% seven-year-old wood. Therefore, 5% two-year-old wood can be used to produce pulp without quality losses. RESUMO Árvores de eucalipto de rápido crescimento podem ser danificadas por ventos, principalmente 24 meses após o plantio, mas a baixa qualidade das fibras dessa madeira dificulta a produção de polpa celulósica. O objetivo deste estudo foi avaliar a utilização destes materiais para a fabricação de polpa celulósica em misturas com madeira de árvores de sete anos de idade. Polpa celulósica branqueada foi produzida com 100, 95, 85, 75 e 0% de madeira de árvores de dois clones de Eucalyptus grandis x Eucalyptus urophylla com sete anos de idade, relacionada com a idade de corte. Madeira de árvores de dois anos de idade, mais susceptíveis a danos por ventos, foi utilizada para completar cada tratamento. Um disco de espessura de 5 cm foi retirado na altura do peito (1,3 m) em cada árvore para a caracterização anatômica e ultra-estrutural. As árvores com sete anos apresentaram maior frequência de vasos, fibras com maior comprimento, fração parede, módulo de elasticidade e dureza e menor ângulo microfibrilar. O refino nas polpas diminuiu a opacidade e o volume específico e aumentou a resistência a passagem do ar e as propriedades mecânicas. A adição de madeira de dois anos de idade na produção de polpa celulósica reduziu a resistência mecânica e opacidade e aumentou a resistência à passagem de ar. A proporção da madeira de dois anos de idade, que pode ser utilizado na produção de polpa celulósica variou com o clone, parâmetro avaliado e intensidade do refino. No entanto, a polpa celulósica produzida com 5% de madeira de dois anos de idade, e 95% de madeira de sete anos de idade, foi semelhante aquela com 100% de madeira de árvores de sete anos de idade. Portanto, cinco por cento de madeira de dois anos de idade pode ser utilizado para a produção de polpa celulósica sem perda de qualidade.

O setor de celulose e papel apresenta crescimento acima da media nacional, entretanto isto nao seria possivel sem adequar as etapas de producao, como o refino, em relacao a materia prima. Desse modo o objetivo foi avaliar o refino em diferentes polpas de eucalipto. Dez amostras de madeira foram submetidas a polpacao e branqueamento, logo apos as polpas foram submetidas ao refino e aos testes fisicos, mecânicos e opticos conforme normas da TAPPI. O refino aumentou o consumo de energia e o Grau Schopper Riegler de forma linear. Para as propriedades fisicas, a diminuicao da espessura pelo refino aumentou o peso especifico aparente em detrimento do volume especifico aparente. O refino melhorou as propriedades mecânicas, entretanto o indice de rasgo reduziu em polpas submetidas ao refino com maior intensidade. Por fim, o refino piorou as propriedades opticas do papel. O refino atuou de diferentes formas nas propriedades do papel, sendo assim, a aplicacao desta tecnica deve ser adaptada a finalidade do produto.

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.

Esta faltando cadastrar palavras chaves. Este trabalho teve como objetivo determinar a influência da idade e de diferentes materiais genéticos de Eucalyptus sp. na produção de madeira para energia. Neste estudo, foram avaliados três clones de Eucalyptus sp., em quatro idades diferentes, aos 3, 4, 5 e 7 anos, sendo provenientes da Gerdau S/A. De cada árvore foram retirados cinco discos (0%, 25%, 50%, 75% e 100% da altura comercial do tronco), bem como determinados a densidade básica, o poder calorífico superior e a análise elementar da madeira, e, como base nesses valores, foi possível estimar a quantidade de energia m-3. Observou-se que houve efeito da idade e do material genético para a densidade básica da madeira e para o poder calorífico superior. Verificou-se ainda que a quantidade de energia m-3 aumentou com a idade, e houve diferença significativa entre os três materiais genéticos avaliados. O clone GG 680 apresentou melhor desempenho dessa variável, apresentando, aos 7 anos, 2.943 kW.h.m-³. Cabe ressaltar que a escolha do melhor material genético deve levar em consideração as características tecnológicas da madeira, bem como a sua produtividade e efetividade técnica de produção. The present study aimed to determine the influence of age and different genetic material of Eucalyptus sp. in wood energy production. Therefore, we evaluated three Eucalyptus sp. clones from Gerdau S/A, at four different ages: 3, 4, 5 and 7 years. Five discs were removed from each tree (0%, 25%, 50%, 75%, 100% of the trunk commercial height), and the wood basic density and calorific value were determined. Based on these values we estimated the energy m-3 amount. We observed an effect of age and genetic material for the wood density and the calorific value. Moreover, the amount of energy m-3 increased with increasing age, and the three genetic materials evaluated were significantly different between them. The GG 680 clone showed better performance for this variable, presenting at seven years 2,943 kW.h.m-³. Note that the selection of the best genetic material must consider the wood technological characteristics, as well as their productivity and effectiveness of technical production.

Drying is an important step to using wood and anatomical characteristics influence this process. Thus, the objective of this work was to evaluate the relationship between anatomy and wood drying. Samples with 2 x 2 x 4 cm were obtained from eight Eucalyptus urophylla x Eucalyptus grandis clones at 1.3 m height to evaluate the anatomy and drying in climate chamber during 15 days. Cell wall fraction was established as the parameter that best correlated with drying, the Pearson correlation coefficient between this parameter and moisture was -0.8986, -0.6580, 0.9216, 0.8743, 0.7131 and 0.8727 for saturated wood, and after 1, 2.5, 5, 10 and 15 days of drying, respectively. The frequency and vessel size, as well as the height and width of the rays showed low relation with wood drying. Wood anatomy, mainly the cell wall fraction, influences moisture losses and should be considered in wood drying programs. RESUMO A secagem é uma importante etapa para utilização da madeira e as características anatômicas influenciam neste processo. Desse modo, o objetivo foi avaliar a relação entre a anatomia e a secagem da madeira. Amostras de 2 x 2 x 4 cm de madeira foram retiradas de oito materiais de Eucalyptus grandis x Eucalyptus urophylla, a 1,3 metros acima do solo para avaliação da anatomia e secagem em câmara climática durante 15 dias. A perda de umidade foi maior nos primeiros dias de secagem e todos os materiais alcançaram a umidade de equilíbrio com 15 dias de secagem. A fração parede foi o parâmetro que melhor se relacionou com a secagem, sendo que o coeficiente de correlação de Pearson entre este parâmetro e a umidade foi de -0,8986; -0,6580; 0,9216; 0,8743; 0,7131 e 0,8727 para a madeira saturada e após 1; 2,5; 5; 10 e 15 dias de secagem, respectivamente. O diâmetro e a frequência de vaso e a altura e a largura dos raios mostraram baixa relação com a secagem. A anatomia, principalmente a fração parede, influenciou a perda de umidade e por isto, deve ser considerada na elaboração de programas de secagem da madeira.

Resumo: O objetivo do trabalho foi determinar o efeito da combustao dos gases da carbonizacao para reducao das emissoes no rendimento gravimetrico em carvao vegetal, madeira parcialmente carbonizada e finos. Para realizacao das carbonizacoes foi utilizado um sistema forno-fornalha, com capacidade para 10 estereos de madeira. A madeira utilizada foi de Eucalyptus sp., com 8 anos de idade. De acordo com os resultados obtidos, a combustao dos gases nao influenciou o rendimento em carvao vegetal, porem reduziu a proporcao de madeira parcialmente carbonizada e aumentou a quantidade de finos. Palavras-chave: queima de gases; reducao da emissao de poluentes, reducao de poluentes

O artigo não contém o resumo em português. It is well known that pH is an important parameter for controlling the eucalyptus pulp bleaching when using the final chlorine dioxide stage, since it affects the effectiveness of the process. Recommendations found in the literature for operating are in the 3.5 to 4.0 range. However, in this paper it was shown that final chlorine dioxide has better performance, with significant brightness gain while also preserving pulp quality, when it is operated at near neutral pH. This result can be explained by the generation of sodium bicarbonate in situ upon adding carbon dioxide at this stage.

Embora nos últimos anos diversas pesquisas tenham sido desenvolvidas com o intuito de melhorar os índices de qualidade da madeira (densidade básica, composição química), grande parte da produção brasileira de carvão ainda ocorre em fornos com baixo rendimento gravimétrico e com emissões de gases poluentes. Na tentativa de alterar esse cenário, este trabalho objetivou avaliar o funcionamento de um sistema forno-fornalha e também o ajuste de faixas de controle da carbonização em função do tempo e da temperatura, levando-se em consideração a degradação térmica da madeira, com vistas a maximizar o rendimento em carvão vegetal. Foram construídos três fornos circulares de alvenaria acoplados a uma fornalha, para queima dos gases gerados durante a carbonização. O controle da carbonização foi realizado através da mensuração da temperatura interna com sensor infravermelho. De acordo com os resultados, o controle da carbonização realizado com base nas faixas de carbonização proporcionou rendimento médio de 33% de carvão, 8% de atiço e 3% de finos. A fornalha mostrou-se eficiente na redução de emissão de fumaça para o ambiente, funcionando durante um terço do tempo de carbonização. Conclui-se que o sistema forno-fornalha apresenta produção satisfatória de carvão vegetal, com baixa emissão de fumaça durante a carbonização da madeira. Although in recent years several studies have been done with the aim of improving the wood quality indices (basic density, chemical composition), much of the Brazilian charcoal production still occurs in kilns that have low gravimetric yield and uncontrolled emissions of polluting gases. In an attempt to change this scenario, this work was developed with the objective of evaluating the operation of a kiln-furnace system. The work also aimed to adjust carbonization control ranges according to temperature and time, taking into account the thermal degradation of wood in order to maximize the yield of charcoal. Three kilns were built, attached to a furnace for burning the gases generated during the carbonization. Control of carbonization was conducted using internal temperature, measured by an infrared temperature sensor. According to the results, controlling time and temperature during the carbonization provided average gravimetric yields of 33% charcoal, 8% semi-carbonized wood and 3% fines (particle size less than 12.7 mm). The furnace was efficient in reducing fume to the environment, working for a third time carbonization. It is concluded that the kiln-furnace system presents satisfactory production of charcoal, with low fume during carbonization.

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.