abstract
The effect of urea on the cellulose degradation under conditions of alkaline pulping has been studied using purified cellulose powder. The increased cellulose yield in the presence of urea was assigned essentially to the carbamation reactions which were confirmed by elemental analysis, UV-resonance Raman and solid-state C-13 nuclear magnetic resonance spectroscopy. The stabilizing effect of urea on the cellulose peeling reactions during heating up period of pulping process was suggested based on kinetic studies and additionally confirmed in model reactions using cellobiose. The reaction products formed in alkaline urea solutions were analysed by tandem electrospray ionization mass spectrometry and the occurrence of Maillard type reactions between reducing end groups of cellobiose and urea were evidenced. Both Maillard type reactions and carbamation of reducing end groups were proposed to be a part of cellulose protection mechanism against peeling under the conditions of alkaline pulping.
keywords
CARBONYL GROUPS; MASS-SPECTROMETRY; HOT ALKALI; KINETICS; OLIGOSACCHARIDES; POLYSACCHARIDES; HYDROCELLULOSE; ADDITIVES; PRODUCTS; WOOD
subject category
Materials Science; Polymer Science
authors
Ershova, O; da Costa, EV; Fernandes, AJS; Domingues, MR; Evtuguin, DV; Sixta, H
our authors
Dmitry Evtyugin
Associate Professor with Aggregation
acknowledgements
Authors acknowledge Portuguese Foundation for Science and Technology (FCT) for the financial support of this work within the scope of CICECO grant PEst-C/CTM/LA0011/2011 and TEKES-the Finnish Funding Agency for Technology and Innovation. The financial support received from Andritz Oy, Danisco Sweeteners Oy, Metsa Fibre Oy, Stora Enso Oy and UPM is also gratefully acknowledged. Authors thank Lidia Testova and Karlo Nieminen from Aalto University (Finland) for their help with kinetic modeling.