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通过改良蒸煮制得的硫酸盐浆中含有60～75mmol/kg的己烯糖醛酸(HexA),相当于6～7.5个卡伯值单位。HexA并不与氧反应,在氧脱木素阶段只能去除很少一部分,因此使漂白效率降低25%～35%。本研究对卡伯值为14～21、用和不用两段氧脱木素桉木浆的ECF漂白的经济效益进行了评价。漂白流程包括去除HexA的特殊漂白阶段。结果表明,采用氧脱木素在经济上并不具有吸引力,尤其对那些卡伯值低而HexA含量高的浆料;但不用氧脱木素的漂白流程又面临非常严峻的环境挑战。
Kraft pulp prepared by modified cooking contains Hexenoic acid (HexA) in an amount of 60 to 75 mmol / kg, corresponding to 6 to 7.5 kappa number units. HexA does not react with oxygen, removing only a small fraction of the oxygen delignification stage, thereby reducing bleaching efficiency by 25% to 35%. This study evaluated the economic benefits of ECF bleaching with kappa numbers of 14 to 21 with and without two stages of delignification of eucalyptus pulp. The bleaching process includes a special bleaching stage to remove HexA. The results show that the use of oxygen delignification is not economically attractive, especially for those with low Kappa numbers and high HexA contents; however, the bleaching process without oxygen delignification poses a very serious environmental challenge.