【作者】 赵强；

【导师】 蒲俊文；

【作者基本信息】 北京林业大学 ， 林产化学加工工程， 2010， 博士

【摘要】 充分利用速生材,大力发展高得率制浆,对缓解纤维原料短缺的现状具有重要现实意义,但高得率浆的白度不高是一个制约因素,深入研究高得率浆的漂白显得尤为重要。高得率浆的常规H₂O₂漂白存在白度增值低、漂白效率不高、无效分解多等缺点。该研究以欧洲黑杨CTMP及三倍体毛白杨CMP为实验原料,通过各种清洁、环保的化学或物理的处理手段降低H₂O₂的无效分解,提高其漂白效率,实现速生杨化机浆的高效、清洁漂白。系统研究了杨木化机浆过氧化氢漂白（P）、H₂O₂/TAED漂白体系（PT）、超声波助漂过氧化氢漂白、H₂O₂置换漂白（PD）、H₂O₂/TAED置换漂白工艺。研究了杨木化机浆H₂O₂/TAED漂白的各种化学预处理对漂白效果的影响,包括漂前螯合、乙酸酐活化、二次加碱及ClO₂活化等处理方法,进一步提高漂剂的漂白效率。采用自主设计的新型实验室用置换漂白设备,改善了置换漂白效率及漂白匀度。提取欧洲黑杨及三倍体毛白杨两种杨木木素,对木素进行漂白处理,利用红外光谱仪、紫外光谱仪、元素分析、凝胶色谱仪及核磁共振光谱仪（¹H-NMR）等仪器分析手段,研究了木素经漂白处理后结构的变化。系统对比研究了杨木化机浆三种漂白工艺（P、PD、PT）的漂白机理。得到的主要结论如下:确定出了探头式超声波发生仪预处理三倍体毛白杨化机浆H₂O₂漂白的最佳预处理条件。经最佳超声条件处理后,H₂O₂用量为2%时,纸浆白度增值达到20.7%ISO。超声波加活化剂协同漂白工艺效果较佳,白度增值达到了21.2%ISO。优化了杨木化机浆H₂O₂/TAED漂白工艺,得到较适宜的工艺条件为:浆浓10%,H₂O₂用量4%,用碱量为2%,TAED与H₂O₂摩尔比为0.3,反应温度70℃,漂白时间60min,此条件下白度增值可达到23.6%ISO。组合漂白P_T2P₄漂序与P_T3P₃、P_T4P₂相比,所得浆具有较高的白度增值（33.5%ISO）,较好的强度性能。研究了二次加碱、乙酸酐活化及ClO₂活化对杨木化机浆H₂O₂/TAED漂白效果的影响,确定出了最佳处理条件。其中,二次加碱方式表现较佳。两段组合漂白工艺中,P_TS1P₃与P_T1P₃相比,白度提高了4.5%ISO。确定出较佳的杨木化机浆过氧化氢置换漂白工艺,此条件下白度增值为30.6%ISO。杨木化机浆H₂O₂/TAED置换漂白的动态漂白时间7min,漂白温度70℃,活化剂量与H₂O₂摩尔比为0.05为宜,白度增值可达到31.6%ISO。改良后设备与常规设备进行过氧化氢置换漂白的对比数据显示,改良设备漂白所得浆白度比常规设备浆的白度高。杨木化机浆H₂O₂/TAED五段逆流置换漂白所得浆的白度增值为33.4%ISO,比相同实验条件下单段置换漂白提高了2.4%ISO。五段逆流置换漂白中过氧化氢的实际消耗量比单段置换漂白下降了12.9%。由木素红外光谱分析可知,在漂白过程中木素发生了脱乙酰基作用及其他酯键的断裂,H₂O₂/TAED漂白系统与前两种处理方式比较,作用更强。H₂O₂/TAED漂白对羰基的破坏作用优于过氧化氢及过氧化氢置换漂白体系。NaBH₄还原铁螯合法测定木素中的邻醌含量。结果表明,H₂O₂/TAED漂白木素中邻醌含量降低最多,这也正是H₂O₂/TAED漂白体系可大幅度提高纸浆白度的另一个原因所在。对比研究了欧洲黑杨木素和三倍体毛白杨木素经过三种漂白体系处理后的变化情况。研究发现,同样处理条件下,与欧洲黑杨木素相比,三倍体毛白杨木素共轭羰基及邻醌含量的降低幅度较大。¹H-NMR分析结果表明,愈创木基苯环上的质子峰,经P、PD、PT（H₂O₂漂白、H₂O₂置换漂白、H₂O₂/TAED漂白）处理后木素中愈疮木基结构比例都不同程度减少,这表明愈创木基容易反应。甲氧基质子峰经H₂O₂漂白、H₂O₂置换漂白后面积增加,H₂O₂/TAED漂白后降低。芳香族乙酰基质子峰经三种漂白方式处理后相对吸收强度增加,说明芳基醚键对三种漂白体系均不稳定,漂白处理过程中发生断裂产生了新的酚羟基。更多还原

【Abstract】 Taking fast growing wood as raw material to develop high yield pulping process is an important way to resolve the fiber materials shortage of pulping industry.But the pulp brightness may be a restrict factor as it is not easily bleached to high target.Hydrogen peroxide has been widely used in mechanical pulp bleaching.But conventional H₂O₂ bleaching has some shortcomings,such as the brightness gain and bleaching efficiency are low and the invalid decomposing reactions are violent.To improve H₂O₂ bleaching efficiency,ultrasonic radiation,TAED activator and H₂O₂/TAED displacement bleaching were carried out in this research.The H₂O₂/TAED bleaching process of poplar CMP and its pretreatment methods were fully studied.The results indicated that second adding NaOH,acetic anhydride activating,and ClO₂ activating can improve H₂O₂ bleaching efficiency and pulp brightness effectively.The H₂O₂ and H₂O₂/TAED displacement bleaching processes of poplar CMP were confirmed.The modified displacement bleaching apparatus for laboratory use was initially made to decrese channelling effect of conventional apparatus.The FTIR,element analysis,gel permeation chromatography（GPC） and proton nuclear magnetic resonance（¹H-NMR） were employed in this research in the analysis of components changes in poplar lignins before and after bleaching treatments.The optium pretreatment conditions of probe-type ultrasonic radiation for Triploid Populus tomentosa CMP were confirmed.The brightness gain was 20.7%ISO with the optium ultrasonic radiation pretreatment and 2%H₂O₂ bleaching.For the ultrasonic-H₂O₂ bleaching of Populus nigra L.CTMP,the pulp brightness gain with PT bleaching system was 19.9%ISO,which higher 7.3%ISO than conventional H₂O₂ bleached pulp.The brightness gain gets the highest value（21.2%ISO） with activator and ultrasonic radiation coexistence.Study on H₂O₂/TAED bleaching process of Populus nigra L.CTMP showed that the suitable bleaching condition were:pulp consistency 10%,H₂O₂ 4%,NaOH 2%,the molar ratio of TAED and H₂O₂ is 0.3,temperature 70℃,bleaching time 60min and the brightness gain can get 23.6%ISO.The results indicated that the P_T2P₄ procedure has better bleaching result（brightness gain was 33.5%ISO） than P_T3P₃ and P_T4P₂ procedure at the same H₂O₂ usage.The results showed that second adding NaOH,acetic anhydride activating,and ClO₂ activating can improve H₂O₂ bleaching efficiency and pulp brightness effectively.Among of them,the method of second adding NaOH was better.The brightness gain of P_Ts1P₃ was higher 4.5%ISO than that of P_T1P₃. P_TY bleaching procedure can bleach the pulp to 83.0%ISO brightness.The optimum H₂O₂ displacement bleaching process for Populus nigra L.CTMP were confirmed. Comparing H₂O₂ displacement bleaching process,the H₂O₂/TAED displacement bleaching process has shorter dynamic bleaching time（7min） and lower bleaching temperature（70℃）,and the ratio of TAED and H₂O₂ was 0.05.The pulp brightness gains were 30.6%ISO and 31.6%ISO respectively with two bleaching systems.The brightness of pulp bleached with modified displacement apparatus better than conventional apparatus’.The pulp brightness of H₂O₂/TAED five-stage counterflow displacement bleaching increased 2.4%ISO and H₂O₂ consumption decreased 12.9%than those of single stage bleaching.This indicated that multi-stage counterflow displacement bleaching can decrease H₂O₂ consumption and increase bleaching efficiency.From FTIR absorption,it can be found that the conjungated carbonyl contents were reduced with P, PD and PT treatments.The results from the reduction differential absorption also proof the conclusion. The reduced degree of conjungated carbonyl is PT＞PD＞P.This showed that PT bleaching system has stronger effects on conjungated carbonyl of lignin.The o-quinone contents of bleached lignins which tested by NaBH₄ reduction method were reduced by P,PD and PT bleaching.Among three bleaching processes,PT bleaching made the o-quinone content lowest.Comparing with Populus nigra L lignins,conjungated carbonyl and o-quinone contents in Triploid Populus tomentosa lignins reduced relatively larger at the same bleaching condition.According to the ¹H-NMR results,it can be found that guaiacyl structure reduced with P,PD and PT bleaching.The methoxy proton peak increased after P and PD bleaching but reduced after PT bleaching.It indicated that PT system has more effects on lignin methoxyl than the other two systems. Phenolic hydroxyl contents increase showed that aryl-ether bond is sensitive to P,PD and PT bleaching systems.更多还原