关键词: 蔗渣浆, ECF 短序漂白, 二氧化氯脱木素, 过氧化氢强化氧脱木素, 可吸附有机卤化物, 直接化学品成本

Abstract:

In this paper,first,three typical element chlorine- free (ECF) short- sequence bleaching processes,namely D₀ EpD,OpDEp and OpD,were comparatively investigated.Then,the difference in delignification rate be-tween the chlorine dioxide delignification (D₀ ) and the peroxide- reinforced oxygen delignification (Op) was re-vealed,and the effect of pre- delignification on the subsequent bleaching was analyzed.Finally,the AOX (Absor-bable Organic Halides) emission and the direct chemical cost during the bleaching were discussed.The results in-dicate that (1) D₀ possesses high delignification selectivity; for instance,the delignification rate reaches 40% at aClO₂ dosage of only 0.8% and continuously increases with ClO₂ dosage; (2) Op can not only delignify the residuallignin in pulp but also remarkably improve the pulp brightness to a value much higher than that of D₀ pulp; (3)OpDEp bleaching is more effective than D₀ EpD bleaching at the same chemical dosage in the subsequent bleachingbecause it may result in higher pulp brightness; (4) the final brightness of OpDEp bleached pulp is about 12 per-centage points higher than that of OpD bleached pulp; and (5) at the same pulp brightness,the AOX emitted du-ring the OpDEp bleaching is only about half of that emitted during the D₀ EpD bleaching,and the direct chemicalcost of OpDEp bleached pulp is 40. 00 Yuan/t lower than that of D₀ EpD bleached pulp,which means that OpDEpbleaching is of higher environmental and economic benefits.

Key words: bagasse pulp, ECF short- sequence bleaching, chlorine dioxide delignification, peroxide- reinforced oxy-gen delignification, absorbable organic halide, direct chemical cost