碱抽提强化的麦草浆ClO_2漂白及ECF漂白流程

采用常规碱抽提(E)、氧加强的碱抽提(EO)、H2O2强化的碱抽提(EP)、氧和H2O2强化的碱抽提(EOP)对ClO2脱木素(D0)麦草浆进行改性,考查不同碱抽提方式的改性效果在后续漂段(D1)的体现,并就不同无元素氯(ECF)漂白流程(D0ED1、D0P、D0A/QP、D0EP、D0EPD1、D0EPP)进行对比.结果表明:不同碱抽提方式对D0浆木素的改性效果不同,就对后续漂段D1的影响而言,4种不同碱抽提方式下纸浆的可漂性顺序为D0EOPD0EPD0EOD0E;在4种碱抽提方式所对应的D0ED1漂白流程中,D1段ClO2用量的增加对白度的提升是有限的,以0.8%~1.0%为佳;D0EPD1和D0EPP流程漂白效果优于其它流程,采用D0EPD1和D0EPP流程漂后白度可分别达到82.3%ISO和83.8%ISO,均适用于麦草浆短序ECF漂白.

Chlorine Dioxide Bleaching Reinforced by Alkaline Extraction and Corresponding ECF Bleaching Sequences for Wheat Straw Pulp

Abstract: Applying four kinds of caustic extraction modes to reinforce chlorine dioxide bleaching processes of wheat straw pulp, the impacts of reinforcement were evaluated and various ECF bleaching sequences were investigated comparatively. Results indicated that in D0ED1 bleaching sequences the modification effects of caustic extraction modes on the residue lignin of D0 stage were different. As far as the subsequent D1 stage was concerned, the D1 bleachability order, from easiest to hardest, was D0EOP>D0EP>D0EO>D0E. It was demonstrated that in D0ED1 sequences the enhancement of ClO2 on the brightness of D1 stage was limited, due to approaching the brightness ceiling, which was not advanced significantly with the increasing of ClO2 charges. The optimal charge of ClO2 was 1.0%~1.2% under the conditions of this experimentation. By contrast with various bleaching sequences between D0ED1 and D0EPP, it was found that the improvement of substitute P stage for D1 was significanat, which revealed that the effect of using H2O2 on final bleaching stage was better than that of using ClO2 in D1. By contrast with other ECF bleaching sequences, it was demonstrated that the advancement of D0EPP and D0EOPP sequences were better than those of other sequences. Under the conditions of this experimentation, with D0EPP and D0EOPP bleaching sequences, the final brightness of bleached wheat straw pulp reached 83.8% and 85.7% respectively.