水热预处理对制备桉木溶解浆的影响研究

Effect of Hydrothermal Pretreatment on the Preparation of Eucalyptus Dissolving Pulp

本研究利用水热预处理方法辅助制备桉木溶解浆,并研究了水热预处理最高温度、保温时间、pH值对硫酸盐法制浆得率的影响。结果表明,未漂浆得率随预处理程度的增大而逐渐下降,其中半纤维素的溶出随水解液pH值的升高而增加,在较高pH值下主要以低聚木糖的形式大量溶出,水解液pH值对未漂浆得率的影响显著。研究还发现,漂白浆白度和α-纤维素含量均随水解液pH值的升高而增大。最佳的水热预水解工艺条件为:最高温度170℃、保温时间60 min、pH值4.9。水热预水解后,经硫酸盐蒸煮和无元素氯(ECF)漂白后,获得的浆料综合性能最好,浆料白度93.3%,α-纤维素含量93.32%,达到溶解浆的品质要求。红外光谱表明,水热预处理可以很好地去除原料中的半纤维素。

In this study,a hydrothermal pretreatment method was used to assist the preparation of eucalyptus dissolving pulp. The effects of maximum temperature,time at maximum temperature and pH value of hydrothermal pretreatment on the yield of sulfate pulping were studied. The results showed that the yield of unbleached pulp gradually decreased with the intensification of pretreatment. The dissolution of hemicellulose increased with the increase of the pH value of the hydrolysate. At higher pH values,it was dissolved mainly in the form of xylo-oligosaccharides,resulting in a significant effect of the pH value of the hydrolysate on the yield of unbleached pulp. The results also showed that the brightness and α-cellulose content of bleached pulp increased with the increase of pH value of the hydrolysate. The optimum hydrothermal pretreatment conditions were as follows:the maximum temperature was 170℃,holding time was 60 min,pH value was 4. 9.After hydrothermal pre-hydrolysis,sulfate cooking and ECF bleaching,the brightness of the bleached pulp was 93. 3% and the content ofα-cellulose was 93. 32%,which reached the quality requirement of dissolving pulp. FT-IR spectrum showed that the hemicellulose in raw materials could be removed well by hydrothermal pretreatment.