芦苇NS法与NS-AQ法蒸煮机理的研究

The Mechanism of Neutral Sulfite and Neutral Sulfite-Anthraquinone Pulping of Reed

采用化学分析、气相色谱、红外光谱和紫外光谱等手段,对芦苇在NS法和NS-AQ法蒸煮中脱木素规律和多糖的溶出规律进行了研究。研究结果表明,在两种方法的蒸煮中,脱木素规律相似,木素脱除都分为三个阶段。

The mechanism of neutral sulfite-anthraquinone (NS-AQ) cooking and neutral sulfite (NS)cooking of reed is undertaken by means of chemical analysis, gas chromatography, infrared spectrometry ad UV-visible spectrometry. The result suggests that the delignification course of NS-AQ cooking is much similar to that of NS cooking. The differences of delignification between NS-AQ cooking and NS cooking are small. The delignification course of cooking can obviously be divided into three phases: the initial delignification phase (from the beginning of the cook to 125℃), in this phase delignification ratio reaches 18% (NS) and 11% (NS-AQ) (on total lignn content); the bulk delignification phase (from 125℃ to at temperature 30 minutes), in this phase delignification ratio reaches 77% (NS) and 71% (NS-AQ); and the final delignification phase (from at temperature 30 minutes to the end of the cook), in this phase the delignification ratio reaches 84% for both processes. The result shows that the yield of carbohydrates in NS-AQ pulp is 57.0% (on raw material), but the yield of carbohydrates in the NS pulp is only 53.9%.The addition of AQ in NS cooking provides approximately 3% pulp yield with similar lignin content. The result also suggests that the dissolving of carbohydrates comes about in the later part of the teperature rising stage. It is found that polysaccharose of reed is mainly composed of gLu., xyl. and ar.. During both cooking processes, similar dissolution coefficients are oberserved, i. e.: ar.>xyl>man.>glu.. The result of chromotographic analysis revesals that powder AQ is slowly dissolved in the course of cooking. The content of AQ in the cooking liquor reaches a miximum value (60% of its initial charge) after one hour at 165℃., and then begins to decline until it becomes 25.6% of the initial AQ charges at the end of the cook. IR and UV spectra show that lignins dissolved at different cooking phases are of similar structure.