Delignification of bamboo ( Bambusa procera acher) : Part 1. Kraft pulping and the subsequent oxygen delignification to pulp with a low kappa number

Abstract

Delignification of bamboo ( Bambusa procera acher) was carried out by conventional kraft and soda pulping under varying conditions to determine the relationships between selected cooking parameters (EA 14–20%, sulfidity 0–45%, maximum temperature 165 and 170 °C, and time at maximum temperature 30–95 min) and pulp properties (kappa number, viscosity, and yield). Results indicated that in order to obtain relatively low kappa numbers (17–24), high sulfidity (35–45%) at lower EA (14–16%) increased both pulp viscosity and yield compared to the case of low sulfidity (0–15%) at higher EA (16–18%). Pulp with lower kappa numbers (11–15) and acceptable viscosities (1080–1190 ml/g) can be obtained at a sulfidity level of 25–35% with 18% EA or at a sulfidity level of 15–35% with 20% EA. It was further shown that bamboo kraft pulp was easily delignified by oxygen–alkali delignification to a low kappa number (7–9) without any significant loss in viscosity.