Pulping of Hybrid Acacia Planted in a Social Forestry Program in Bangladesh

Abstract

Acacias have been planted and it was found that Acacia auriculiformis, Acacia mangium and their hybrid are promising species with respect to their survival and growth performance in Bangladesh. Therefore, these three species have been introduced into a social forestry program in Bangladesh. In this study, the chemical, physical and morphological characteristics of wood originating from plantation A. auriculiformis, A. mangium and their hybrid, grown in Bangladesh, were assessed for their suitability in papermaking. The α-cellulose content of the Acacia hybrid was 45.5%, which was 1.3% lower than that of A. mangium and 2.1% higher than that of A. auriculiformis. Kraft pulping of Acacia hybrid was carried out, with varying active alkali charge and cooking time, and it was observed that the hybrid required a high chemical charge to cook properly. Under the cooking conditions of 18% active alkali charge, 120 min of cooking, a pulp yield of 45.9% was reached, with kappa number 27.6 and with no reject. The pulp yield was quite high, as compared to those of A. auriculiformis and A. mangium. Acacia hybrid and Acacia auriculiformis pulps showed almost similar papermaking properties. The maximum tear index of Acacia hybrid was achieved at a tensile index of 76.3 N.m/g, while it was 61.9 N.m/g for A. auriculiformis and 57.2 N.m/g for A. mangium. At these peak levels, the tear index values are almost similar (10 mN.m 2 /g) for A. auriculiformis and the hybrid. With respect to pulp yield and papermaking properties, the hybrid produced the best pulpwood.

Evaluation of Erythrina fusca Lour. as a pulping raw material

“…One percentage of caustic soda solubility of E. fusca was 12.4%, which was close to A. oriculiformis (Haque et al 2019b). This is attributed to the presence of lower inorganics, tannins, gums, sugars and of lower molecular carbohydrates and other alkali-soluble materials.…”

“…Pentosan content was extremely low (8.24%), which was reflected by holocellulose content (59.2%). The pentosan content was even lower than other common hardwoods (Timell 1967; Patt et al 2006) and native hardwood in Bangladesh (Jahan and Mun 2004; Haque et al 2019b, 2019a) and mangrove species (Mun et al 2011). Hemicellulose facilitates fibre bonding during sheet formation.…”

“…Lignin is an undesirable part of pulping. The lignin content in E. fusca was higher than other common hardwoods for pulping (Patt et al 2006) and T. orientalis (Jahan et al 2010) and close to Acacia hybrid (Haque et al 2019b), those are potential pulpwood in Bangladesh. Pentosan is the main constituent of hardwood hemicellulose.…”

“…As shown in Table 3, the α-cellulose content in E. fusca was 47.0%, which was higher than A . auriculiformis (Haque et al 2019b) and T . orientalis (Jahan and Mun 2004; Jahan et al 2010) grown in Bangladesh, thus suitable for pulping.…”