| 摘要 |
A chlorine-free method for bleaching chemical pulps, particularly kraft pulp, uses a first step of treating the pulp with a hemicellulose acting enzyme of a microorganism. Subsequently, the treated pulp is extracted, treated with chlorine dioxide, re-extracted and retreated with chlorine dioxide to result in a brightness level of at least 88. The enzyme may be a xylanase or a mannanase or a mixture. The extraction steps may involve the addition of oxygen under pressure or peroxide. A hypochloride treatment may follow the first extraction step to give a six-step process. |
