resumo
BACKGROUND: Increasing the yield of the wood pulping process allows the reduction of specific wood costs. Process modifications with a great impact on pulp yield are the profiling of chemical charges and addition of anthraquinone (AQ). The aim of the present work is to investigate the influence of effective alkali (EA) profiling and addition of anthraquinone on E. globulus kraft pulping performance. The impact of such process modifications on the ECF bleaching process and on the papermaking properties of the resulting bleached pulps is also evaluated. RESULTS: An EA profiling cook may lead to a pulp yield gain, which is more significant as the total EA charge used in the kraft cook increases. AQ addition to kraft pulping leads to a significant yield increase. The ClO2 charge required to fully bleach the pulps is lower for EA profiling and higher for kraft + AQ unbleached pulps. Bleached AQ pulp presents a high beatability due to high pulp xylan retention. CONCLUSION: A low total EA charge is the key parameter for high polysaccharide retention on pulp. AQ addition constitutes a feasible strategy to increase pulp yield. Bleaching performance and papermaking properties of pulps produced with the three different methods may be affected by the kraft pulping modifications. (C) 2008 Society of Chemical Industry.
palavras-chave
YIELD; DELIGNIFICATION; BLEACHABILITY; WOOD; ANTHRAQUINONE; LABILL; LIGNIN
categoria
Biotechnology & Applied Microbiology; Chemistry; Engineering
autores
Santiago, AS; Pascoal, C
nossos autores
Carlos Pascoal Neto
Diretor do RaizGrupos
agradecimentos
The authors thank the Portuguese Foundation for Research FCT for the financial support of project POCTI/46124/EQU/2002 and PhD grant SFRH/BD/8166/2002, RAIZ for financial support and collaboration in pulping experiments.