Impacto do genótipo, idade de corte e condições de pré hidrólise kraft na madeira de eucalipto para produção de polpa solúvel
Nenhuma Miniatura disponível
Data
2025-03-20
Autores
Santos, Vaniele Bento dos
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal do Espírito Santo
Resumo
The production of dissolving pulp from eucalyptus wood requires a thorough understanding of the raw material properties and processing conditions. Among the main factors influencing pulp quality, genotype, harvest age, and pre-hydrolysis process conditions stand out, with pre-hydrolysis being a critical step for hemicellulose removal. In this context, this study aimed to evaluate the influence of these variables on the young wood of commercial eucalyptus clones and the unbleached pulp obtained through the Pre-hydrolysis Kraft (PHK) process. For this purpose, five trees from two clones, Eucalyptus urophylla (A) and E. urophylla x Eucalyptus spp. (B), aged 3 and 5 years, were analyzed from plantations in the state of Bahia, Brazil. In the first chapter, the impact of genotype and harvest age on wood quality was investigated, considering its chemical, physical, and anatomical characteristics. The results showed that age influenced heartwood formation, the contents of extractives, ash, and hemicelluloses, as well as vessel diameter and frequency. Genotype, in turn, primarily affected the wood's chemical composition, particularly the lignin and hemicellulose contents. Clone A at 5 years demonstrated greater potential for dissolving pulp production, exhibiting higher basic density (450 kg.m³), a higher cellulose content (48%), and lower hemicellulose (23%), lignin (26%), and ash (0.49%) contents. The second chapter addressed the effect of pre-hydrolysis severity on hemicellulose removal. Hydrothermal pre-treatments were applied to wood chips under different time and temperature combinations, with the P-factor used as a severity parameter. The results showed that hemicellulose solubilization reached up to 90% under the experimental conditions, with an optimized point identified at a P-factor of 873, ensuring effective hemicellulose removal without compromising the cellulose fraction. Additionally, regression models were developed to predict process yield and lignocellulosic component removal, providing insights for the industrial optimization of pre-hydrolysis. In the third chapter, the impact of pre-hydrolysis severity on the quality of unbleached pulp obtained via the PHK process was evaluated. Increased severity significantly reduced the Kappa number and pentosan content, while leading to improvements of up to 8.6% in brightness and 7.2% in pulp crystallinity index. However, these advantages were accompanied by a reduction in yield and pulp viscosity, as well as an increase in specific wood consumption. A P-factor of 432 emerged as a viable alternative to balance efficiency and sustainability in dissolving pulp production. Thus, the findings of this study provide strategic insights for the dissolving pulp industry, supporting the selection of genetic materials, the determination of harvest age, and the optimization of pre-hydrolysis conditions.
Descrição
Palavras-chave
Qualidade da madeira , Fator de severidade , Pré-hidrólise Kraft (PHK) , Hemicelulose , Número Kappa