resumo
The aim of this work was to evaluate the impact of anthraquinone (AQ) addition and sulfidity (S) reduction on pulping performance of Eucalyptus globulus wood. Different levels of sulfidity and several charges of AQ for each sulfidity level were used. For the same sulfidity, increasing AQ charge promoted increasing delignification rate until a certain pulp kappa number limit was reached. This kappa number limit was higher for the pulps produced with lower sulfidities. Increasing AQ charge also promoted higher polysaccharide retention on pulp. Pulps produced with constant effective alkali (EA) charge and sulficlities of 10% or 20% were submitted to carbohydrate analysis. For the pulps produced with 10% sulphidity, increasing AQ charge from 0.06% to 0.15% led to an increase of screened yield of 0.6% and this increase can be attributed essentially to an increase in cellulose retention. On the other hand, for the pulps produced with 20% sulphidity, increase of AQ charge from 0.02% to 0.10% produced an increase of screened yield of 0.9% and in this case the increase was attributable to both xylan and cellulose retention enhancement. The maximum xylan retention on pulps, produced with constant EA charge of 13.6%, is about 60%. This high xylan retention value was due not only to the AQ stabilization effect but also to the peculiar features of the main hemicellulose of E globulus wood.
palavras-chave
HARDWOODS; LABILL
categoria
Materials Science
autores
Santiago, AS; Neto, CP
nossos autores
Carlos Pascoal Neto
Diretor do RaizGrupos