Removal of hexenuronic acids by extended oxygen delignification of high-kappa eucalyptus kraft pulp
Source abstract
Abstract
Abstract The presence of hexenuronic acids (HexAs) in kraft pulp interferes with bleaching by increasing the consumption of bleaching chemicals and compromising brightness stability. This study investigated the removal of HexAs during the extended oxygen delignification of eucalyptus kraft pulp with a high initial kappa number (64). Response surface methodology was used to evaluate the effects of temperature (80, 100, 120 and 140 °C) and alkali charge (15, 30, 45 and 60 kg t −1 ), both individually and interactively, under three conditions: without additives, with 0.05 % anthraquinone, and with 0.05 % ethanol (based on oven-dry pulp weight). The initial HexAs content (20.09 μmol g −1 ) was significantly reduced under severe conditions, especially in the presence of ethanol, which achieved a maximum reduction of 11.69 μmol g −1 (58.2 %). The removal of HexAs showed a strong dependence on the interaction between temperature and alkali charge, and the observed trends mirrored those of residual lignin, suggesting a similar response to the oxidative alkaline conditions. Among the treatments, ethanol was the most effective, whereas anthraquinone resulted in a limited reduction in HexAs content. These findings highlight the potential of optimized oxygen delignification for effectively reducing HexAs levels.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Lignin and Wood Chemistry · Biofuel production and bioconversion · Catalysis for Biomass Conversion
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Department of Forestry Science, Faculty of Agricultural Sciences , São Paulo State University , University Avenue, 3780, 18610-034 , Botucatu , SP , Brazil
Department of Forestry Sciences , “Luiz de Queiroz” College of Agriculture, University of São Paulo , Padua Dias Avenue, 11, Post Office Box: 9, 13418-900 , Piracicaba , SP , Brazil
Funding
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) [partial funding]
References (44)
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