Effect of sulfidity on chemical properties of sulfate pulp from the river red gum (Eucalyptus camaldulensis Dehnh.)
1995
Sawitree Pattanopast
This research is to investigate the factor effect of sulfate pulping including cooking time, sulfidity and active alkali. Red gum, Eucalyptus camaldulensis Dehnh., 5 years old, was used as raw material. It was debarked, chipped, screened, seasoned and weighed before pulverized into pulp. More than 50 kg of air dried chips were used in this experiment. About 2.5 kg of chips were selected at random for physical and chemical properties. The remaining chips were packed in plastic bags at 350 g per bag for pulping. The results are summarized as follows. Total cooking conditions were made with 36 factors as follows: 6 levels of cooking time at 170 deg C up to 180 min, 3 levels of sulfidity up to 25 percent, and 2 levels of active alkali at 16 and 18 percent. The residual mass of solid (pulp and reject) and its cell wall components were analyzed every condition. The maximum pulp yield, holocellulose and pentosan contents in pulp are 46.0, 97.0 and 13.0 percent respectively. The minimum lignin content and kappa number in pulp are 2.72 percent and 28.6 respectively. The regression equations, among residual mass (Y), kappa number (K) and lignin content (L) with respect to H-factor (H) and effective alkali (EA), and coefficient of determinations (R sup (2)) are as follows. Y = 141.1 - 14.12 (log H) (EA sup (-0.057)), R sup (2) = 94.71 percent; K = 396.7 - 77.33 (log H) (EA sup (-0.211)), R sup (2) = 91.11 percent; L = -4.928 + 0.159 K, R sup (2) = 98.99 percent. The physical properties of chemical pulps from 12 cooking conditions were evaluated and gave the maximum results as follow: tensile index 60.9 Nm/g burst index 4.75 k.Pa. square m/g tear index 9.80 m.N. square m/g and folding endurance 66 times.
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