稻草在LiCl/DMSO中的溶解及再生性能

  目的  以球磨稻草(水稻Oryza sativa秸秆)为原料，通过氯化锂/二甲亚砜(LiCl/DMSO)溶剂体系处理，探讨球磨稻草在LiCl/DMSO溶剂体系中的溶解行为及再生特点。  方法  选取稻草叶、带节的秆、不带节的秆、全秆等4个部位，设置0.5、1.0 h球磨时间，设置LiCl质量分数为2%、4%、6%、8%的LiCl/DMSO溶剂体系进行溶解后再生，按照标准方法测定纤维素、半纤维素、木质素和灰分等化学成分，通过碱性硝基苯氧化来测定木质素结构单元的产率，分析木质素的缩合程度，采用X射线衍射图谱计算纤维素结晶度，比较再生前后的纤维素的结晶区变化。  结果  球磨1.0 h秆和叶均可完全溶解于LiCl/DMSO溶剂体系，质量分数为8%的LiCl/DMSO溶剂体系可溶解的叶和秆的质量分数能达到10%。经水再生后，80%以上的木质素得以保留，秆中木质素保留率可达到87.5%；经X射线衍射分析，叶中纤维素的结晶度从37.8%下降至27.5%，秆从43.1%下降至26.5%；硝基苯氧化结果表明:再生后，各部位中木质素结构未缩合单元含量均有所增加。  结论  球磨时间、LiCl的质量分数均会影响草粉在LiCl/DMSO溶剂体系中的溶解，再生后，球磨草粉中的化学成分再生能力强，经比较叶中纤维素、木质素的再生能力最低；叶、秆中灰分的分布、沉积有所不同，叶中的灰分再生能力高于秆。各组分经球磨后木质素的缩合程度降低，球磨改善了硝基苯氧化环境。再生后各部位中的纤维素结晶度有所下降，结晶区受到一定程度的破坏。图6表4参36

Dissolution and regeneration of rice straws with LiCl/DMSO

Objective]With the straw of Oryza sativa selected as raw materials,this study is aimed at an investigation of the dissolution behavior and regeneration characteristics of straw samples dealt with the LiCl/DMSO solvent system.Method]With the national standard method employed,the four samples of straw(internode with knot,stem without knot,leaf and whole straw)were treated with the LiC1/DMSO system before an analysis was conducted of the general chemical composition of cellulose,hemicellulose,lignin and ash.On top of this,the effect of dissolution and regeneration of rice straw on the cellulose crystallization zone was investigated with the crystallinity calculated employing X-ray diffraction after the yield of lignin structural units produced by alkaline nitrobenzene oxidation was measured and the condensed degree of lignin was analyzed.Result](1)Both of stem and leaf with 1.0 h ball milling could be completely dissolved in LiCl/DMSO solvent system with a dissolution rate up to 10%even in the 8%LiCl/DMSO solvent system;(2)After water regeneration,more than 80%of the lignin could be retained with that of the stem reaching 87.5%;(3)The cellulose crystallinity was decreased from 37.8%to 27.5%for the leaf and from 43.1%to 26.5%for the stem;(4)The uncondensed units of lignin of all four samples were increased,as observed in the results of alkaline nitrobenzene oxidation.Conclusion](1)Both ball milling time and LiCl concentration affect the dissolution of rice straw in LiCl/DMSO solvent system;(2)In terms of regeneration,the chemical content displays high capacity and in comparison,that of the cellulose and lignin was the lowest in leaf sample while with a different ash distribution,the regeneration capacity of the leaf was higher than that of the stem;(3)After ball milling,the condensation degree of lignin decreases while the oxidation environment of nitrobenzene and homogeneous reaction was improved;(4)After regeneration,it was showed in the X-ray diffraction analysis that the crystalline region of cellulose was damaged to a certain extent and the crystallinity decreased.