resumo
The reasons for the improved brightness stability of pulp bleached in the final stage with hydrogen peroxide than with chlorine dioxide have been studied. UV-vis Diffuse Reflectance and UV Resonance Raman micro-spectroscopy @ 325 nm were employed to evaluate the chromophores formation/degradation in fully bleached eucalypt kraft pulp while applying a final chlorine dioxide or a hydrogen peroxide bleaching stages. Spectroscopic data were coupled to wet chemistry and mass spectrometry analyses of degradation products arisen during hydrothermal ageing of bleached pulps. The complementary analyses have revealed the important role of partially oxidised carbohydrates and of the residual xylan-lignin complex in ageing reactions. The leaching of degradation products from pulp during the final bleaching stage, rather than specific oxidation patterns of pulp polysaccharides with the bleaching agent was suggested to be a crucial factor predetermining the extent of brightness reversion of pulp. (c) 2012 Elsevier Ltd. All rights reserved.
palavras-chave
KRAFT PULP; EUCALYPTUS-GLOBULUS; RAMAN-SPECTROSCOPY; GLUCURONIC-ACID; CHEMICAL PULPS; CHROMOPHORES; LIGNIN; HEAT; IDENTIFICATION; TEMPERATURE
categoria
Chemistry; Polymer Science
autores
Loureiro, PEG; Domingues, MRM; Fernandes, AJS; Carvalho, MGVS; Evtuguin, DV
nossos autores
Dmitry Evtyugin
Professor Associado com AgregaçãoProjectos
agradecimentos
Authors are grateful to FCT (Portuguese Foundation for Science and Technology) and UE - FEDER (European Fund for Regional Development) through the Competitiveness Factors Operational Programme (COMPETE) for the financial support of this work within the scope of Projects PTDC/EQU-EQU/113547/2009 (COMPETE, ref. FCOMP-01-0124-FEDER-015254) and PTDC/QUI-QUI/100044/2008 (COMPETE, ref. FCOMP-01-0124-FEDER-010812) and POPH-QREN funding program and FCT-MCTES for the doctoral degree grant SFRH/BD/29690/2006.