No abstract

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.

Wood is the most expensive fraction in the pulp production costs. Therefore, strategies for increasing wood quality such as faster growth, higher wood basic density and lower lignin content are drivers to pulp mills. The cultivation site as well as the eucalypt clones influence the wood quality, which, in turn, affects the pulp production performance. Thus, this work aims to evaluate the effect of the site on the wood quality for the pulp production. Three eucalypt clones from five different sites in Brazil were used in this study. These samples were selected aiming to represent a gradient of environmental stress. It was possible to observe a reduction in the content of extractives and lignin and an increase in the content of glucans in the sites with less environmental stress, reflecting in the production of pulp with less effective alkali demanded (reduction of 13.5 %) and an increase of 10.5 % in the kraft pulp screened yield. MAIP values of 22.7 ton/ha/year were obtained in the sites with less environmental stress, presenting a lower specific wood consumption. Through the production indicators, it was observed that the C1 clone is more adaptable to the regions of greater environmental stress than the other clones analyzed.

The understanding of the relationship between the properties of wood and charcoal makes it possible to improve the production of charcoal. Therefore, the random forest algorithm was used in this study to analyze the influence of eucalyptus wood properties on the quality of charcoal as well as the accuracy of the predicted values concerning the results estimated by support vector regression and multiple linear regression. Six properties of wood and six properties of charcoal obtained from the hybrid Eucalyptus grandis x Eucalyptus urophylla and from twelve clones of Corymbia torelliana x Corymbia critriodora at the age of seven were measured. In the analysis, the measure of mean decrease in node impurity (residual sum of squares) calculated with the random forest and the copula correlation was used to evaluate the relationship between properties of wood and charcoal. The random forest was compared to the support vector regression and multiple linear regression through the coefficient of determination, linear correlation between observed and predicted values, mean absolute error and root mean squared error. The accuracy of the random forest was greater than that obtained with the support vector regression and multiple linear regression, mainly in terms of the coefficient of determination and the linear correlation between observed and predicted values. The yield and quality of the charcoal produced from clones were mainly influenced by the holocellulose content, heartwood/sapwood ratio, and basic wood density. The apparent relative density of charcoal was the variable in which the random forest algorithm reached the best level of explanation of the variability as a function of the properties of wood, while the minor error was observed for the fixed carbon content.

Lignin is the second most abundant biopolymer on Earth, being the main organic compound present in residual liquors from chemical processes to obtain cellulose. Although almost all of this lignin is currently burned in the recovery cycle of the kraft process, applications in biorefinery have been increasingly studied, due to the richness of functional groups present in this polymer. However, a large industrial application still requires overcoming its difficult workability, since it has high polydispersity and low reactivity. Thus, this study aimed to obtain more homogeneous and pure lignin fractions from the application of one-step and sequential fractionation methods using organic solvents and acid precipitation. The organic solvents used were ethyl acetate, ethanol, methanol and acetone. The pHs tested were 9, 7, 5, 3 and 1, by adding hydrochloric acid. The fractions were characterized in terms of acid- soluble and insoluble lignin, carbohydrates and ashes, as well as by elemental analysis. S/G ratios were determined by Py-GC-MS. All fractions obtained in both fractionation methods showed higher carbon contents, higher purity and lower S/G ratio than the corresponding initial materials (eucalypt kraft lignin and eucalypt kraft black liquor), characteristics that are very favorable for application in biorefinery. Acetone-soluble (sequential) and pH 1 (one- step) precipitated fractions are the most suitable for carbon fiber production. Fractions soluble in ethyl acetate (one-step) and insoluble at pH 3 and 1 (sequential) appear to be the most appropriate for applications that require good oxidative properties. The fractions soluble in ethanol (one-step), methanol (one-step), acetone (one-step) and precipitated at pH 9 (one-step) and pH 5 (sequential) are the ones that allow better chemical substitution in obtaining bioproducts. Fractions soluble in ethanol (sequential) and precipitated at pHs 5 and 1 (sequential) are not of commercial interest due to their low yield. Keywords: Biorefinery. Lignin. Organic Solvents. pH Effect. Eucalyptus.