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Poster Presentation 1-23
Kinetic Parameters of the Treatment of Sugarcane Bagasse and Lignins
Adilson R. Gonçalves
Depto. Biotecnologia – FAENQUIL, CP 116 CEP 12.600-000 Lorena, SP, Brazil
Telephone: 55-12-553-3422, ext. 235; Fax: 55-12-553-3165 E-mail: adilson@debiq.faenquil.br
Sugarcane bagasse was subjected to a steam explosion process designed to separate the main macromolecular products (polyoses, cellulose and lignin). In this work, the kinetics of the main reaction (hydrolysis) of xylans (polyoses) and glucans (cellulose) present in the sugarcane bagasse after steam treatment were studied. The pre-treated bagasse was also extracted with NaOH and the delignification and oxidation of the lignin were studied. Steam explosion was performed with 10 g of sugarcane bagasse from 0 to 60 min, at 165-210°C. Alkaline extraction was performed with the exploded bagasse from 50-100°C for 30 to 480 min at 7 and 10% alkali charge. First-order kinetics was adjusted to the hydrolysis and to the alkaline extraction of the lignin. Kinetic rate constants ranged from 1.38.10-3/min to 19.0•10-3/min for glucane decomposition and from 1.45•10-2/min to 12.3•10-2/min for xylan decomposition. Activation energy for both processes, glucan and xylan decompositon, was 101 and 84 kJ/mol, respectively. On the other hand, for the delignification the activation energy was only 3.1 kJ/mol, showing that the main barrier in the process is the disruption of the fibers and that the removal of the lignin seems to be just a dissolution process. Oxidation of lignin to vanillic acidi and vanillin has a rate constant ranging from 1.49•10-2/min to 4.58•10-2/min.
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