FT–Raman Investigation of Milled-Wood Lignins: Softwood,Hardwood, and Chemically Modified Black Spruce Lignins

Abstract

Raman spectroscopy is being increasingly applied to study wood and other lignin-containing biomass/biomaterials. Lignin's contribution to the Raman spectra of such materials needs to be understood in the context of various lignin structures, substructures, and functional groups so that lignin-specific features could be identified and the spectral information could be interpreted usefully. Additionally, to enhance the utility of Raman as a characterization tool, an understanding of chemical-treatment-induced changes to the lignin spectrum is important. In the present work, Raman spectra of four milled-wood lignins (MWLs)—black spruce, loblolly pine, aspen, and sweetgum—were compared, and using black spruce MWL, spectral changes brought about by alkaline hydrogen peroxide bleaching, hydrogenation, acetylation, and methylation reactions were analyzed. The band intensity changes depended upon the nature of the chemical treatments.     

Effect of Totally Chlorine Free and Elemental Chlorine Free Sequences on Whole Stem Kenaf (Hibiscus cannabinus) Pulp Characteristics

Totally chlorine free (TCF) and elemental chlorine free (ECF) single and multistage sequences were used to bleach whole stem kenaf pulp. The results indicated that in contrast to unbleached kraft wood pulps, kraft kenaf pulps can be easily bleached to a brightness of 91.4% using a four-stage TCF [Q₁(PO)Q₂P] bleaching sequence. The ECF bleaching pulps had slightly higher selectivity and yield than those of the TCF bleached pulps. The strength properties of the TCF [Q₁(PO)Q₂P] and ECF (D₁ED₂EP) bleached pulps were comparable, with the exception of tear index and tensile index, which were slightly higher and lower for TCF pulps, respectively.     

硫酸盐竹浆光催化漂白中部分影响因素的探讨

利用自制光催化漂白反应器,对竹浆光催化漂白过程的部分影响因素进行了研究.实验结果表明:光催化漂白8h后,NaOH用量3%的漂后浆白度比NaOH用量1%的可提高12.4%ISO,但粘度下降67mL/g,显示纸浆光催化漂白过程中控制合理的碱性条件非常重要;与传统的纸浆漂白方式相比,纸浆光催化漂白反应受温度的影响较小,即使在低温(13℃)条件下,纸浆光催化漂白后浆料白度也可以达到81%ISO;另外,浆浓对纸浆光催化漂白反应有较大影响,在光源不变的情况下,随着浆浓的增加,参与光化学反应的纸浆比例相应减少,从而导致漂后浆白度降低.     

双漂法对大豆蛋白纤维漂白的工艺研究

采用双氧水／漂白剂PD—CC双漂法对大豆蛋白纤维漂白，白度可比双氧水单漂法和过醋酸单漂法提高10％，而且漂白后，大豆蛋白纤维的主体结构未发生变化，大豆蛋白含量微降低．能充分体现大豆蛋白纤维本身所固有的特性。     

新闻纸生产用脱墨浆的还原性漂白

分别采用连二亚硫酸钠(Y)、甲脒亚磺酸(FAS)对新闻纸生产用脱墨浆进行了还原漂白的研究,两种还原漂白剂均可获得较高的白度增值和较低的黄度,漂后浆的物理强度较未漂浆有不同程度的改善,而且成本也较过氧化氢低,还原漂白剂代替过氧化氢来进行废报纸脱墨浆的后段漂白是可行的.     

制浆中段废水污染特征及脱色处理方法

研究了木浆和竹浆中段废水的污染特征以及脱色方法.研究结果表明,制浆中段废水的生化性差,其分子质量较大的有机物是废水色度的主要来源,并且随着废水pH值的升高其色度也加深,混凝法是简单有效的脱色处理方法.     

碱法草浆中段废水微电解法脱色

将微电解法应用于碱法草浆中段废水的脱色处理,并讨论了其影响因素。实验结果表明:在搅拌条件下,铁炭质量比1:2、pH为2、用铁量800mg·L-1、反应时间30min,废水色度的去除率可以达到95%,处理后的废水近乎清澈透明。     

碱性H2O2漂白及其对高得率浆性能的影响

高得率浆(HYP)的生产过程中采用碱性H2O2漂白工艺.漂白工段是控制HYP浆性能,使其满足特定纸种对纸浆的质量要求的关键工艺过程.在碱性H2O2漂白过程中,纤维素、木素、半纤维素、果胶、抽出物及其他木材成分发生一系列化学和物理变化.本文对这些变化及草酸钙引起的结垢和阴离子垃圾的产生等问题做了概括性总结.除了白度提高之外,碱性H2O2漂白可以大大提高HYP浆的抗张强度,但同时也在一定程度上降低其光散射系数和松厚度,这3个性能指标互相关联.本文也总结性地讨论漂白对HYP浆性能的影响.     

退浆剂FZ—D的研制与应用

本文分析了短流程工艺和织物经纱浆料情况;介绍了退浆剂FZ-D的性能与应用情况;讨论并经试验证实了用退煮-氧漂工艺在平幅及绳状设备上既加工纯棉又加工涤/棉工艺的可行性。