The effect of wood extractives on pulp properties of maritime pine kraft pulp

• Autor(a) principal: Baptista, Cecília
• Data de Publicação: 2006
• Outros Autores: Belgacem, Mohamed Naceur, Duarte, Ana Paula
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/575
• topic: Maritime pine; Kraft pulp; Organic solvents; Alkaline extraction; Kappa number; Reflectance factor; Bleachability

The effect of wood extractives on pulp properties, namely the colour of the unbleached pulp and its bleaching aptitude, was evaluated by carrying out kraft cookings after extractive removal of the Pinus pinaster wood. The colour of the pulps thus obtained was compared to a reference pulp prepared without any wood extraction. Two types of wood extraction were realised. The first one consisted on using different non-swelling and swelling solvents allying upon 8 different extractions, whereas the second one was an alkaline pre-treatment of the wood chips. For the first set of extractions, acetone and ethanol-toluene appeared to be the most efficient, since the pulps obtained from wood previously extracted by these solvents showed an increase in the reflectance factor by up to 7,5% and a decrease in the kappa number of about 4 points. For the second type of pre-treatment, the results obtained showed improvements of 10% in the reflectance factor of unbleached pulp and about 12% in the kappa number. The influence of the extractives on the pulp bleachability was studied by submitting the most promising samples to a DE bleaching sequence. These pulps showed increments in the reflectance factor more than 30% higher when compared with the reference.