Bulk delignification kinetics at selected vertical heights within jack pine plus trees

Abstract

Pulping kinetics of extractive-free wood from jack pine trees sampled from the Fort Frances, the Atikokan and the Thunder Bay districts of Ontario, Canada, were investigated. Wood samples were cooked at three different temperatures: 140 ~ 155 ~ and 170 ~ with a white liquor concentration of 32 g/L sodium hydroxide and 10.4 g/L sodium sulphide (25% sulphidity). The results indicated that the average activation energy for pulping of trees from the Fort Frances, the Atikokan and the Thunder Bay districts were 91.0, 81.0 and 81.4 kJ/mol, respectively. The differences of activation energy for pulping between sapwood and heartwood were insignificant. Activation energy for pulping of wood increased from top to bottom of the tree.

Pulping Yield and Delignification Kinetics of Heartwood and Sapwood of Maritime Pine

“…Wong et al [9] also found a negligible difference in lignin solubilization between sapwood and heartwood in Pinus banksiana. However, differences between heartwood and sapwood occurred in the initial phase for 1608C and 1708C with a lower lignin solubilization in heartwood, for example, after 5 min at 1708C, 27% lignin was removed from heartwood and 37% from sapwood.…”

“…The activation energies found in this study are in the range of reported values for other species, but only one reference could be found in the literature comparing heartwood and sapwood. Wong et al [9] reported values between 85.2 and 92.0 kJ . mol 21 for sapwood and between 89.6 and 90.6 kJ .…”

“…The relationship between extractives and heartwood has been examined for Pinus contorta [6,7] and P. echinata. [8] For P. banksiana, Wong et al [9] investigated the pulping kinetics of extractive-free wood, including determining the average activation energy, and did not find significant differences between the heartwood and sapwood.…”