Abstract
Alkaline delignification of Acacia nilotica heartwood has been carried out using 10 % Sodium hydroxide and Sodium sulphide as the cooking liquor. Delignification was carried out at 373, 393, 403 and 413 K on Acacia nilotica sawdust of particle-sizes 70, 100 and 120 mesh, for durations ranging from 1 to 3 h. The reactions were carried out in presence and in absence of Ferrous sulphate to determine its catalytic properties in delignification. Maximum delignification achieved was 82.7 %, based on Klason lignin, in 3 h at 413 K for 120 mesh feed. The activation energies for delignification were 20.9275 and 35 kJ/mol, respectively, in presence and in absence of Ferrous sulphate, indicating its significant catalytic effect. A kinetic model for delignification was developed by modification of the Nuclei Growth model. Delignification extent could be predicted from the developed model quite accurately, with R2 values ranging from 0.947 to 0.99.
Published Version
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