辐射松预水解对后续蒸煮及氧脱木素过程木素脱除效果的影响

The Effects of Radiata Pine Prehydrolysis on the Lignin Removal of the Subsequent Kraft Pulping and Oxygen Delignification

本文研究了辐射松木片预水解对蒸煮和后续氧脱木素过程的影响。结果表明,预水解温度为168℃,预水解时间在60~90 min时,半纤维素脱除率大于50%,而纤维素的损失率小于10%,且纤维素聚合度不降低;同时也能促进蒸煮过程及后续氧脱木素过程木素的脱除,蒸煮后纸浆卡伯值降低至16.3,氧脱木素后纸浆卡伯值降低至2.8。当预水解时间超过120 min,预水解则会对后续的蒸煮起阻碍作用,造成蒸煮困难,表现在纸浆卡伯值急剧上升,甚至出现生煮现象。预水解时间控制在180 min之内,预水解可以提高氧脱木素过程中木素的脱除率,预水解时间超过180 min,预水解对氧脱木素的影响则不明显。预水解对蒸煮过程的影响大于对氧脱木素过程的影响,尤其是过度预水解对蒸煮有阻碍作用,但是对后续氧脱木素的影响则不显著。

The radiata pine chips was treated by consecutive prehydrolysis, kraft pulping and oxygen delignification and the effects of prehydrolysis time on the lignin removal efficiency of the subsequent kraft pulping and oxygen del- ignification were investigated. The results showed that prehydrolysis within 60 ~ 90 min could not only remove more than 50% hemicellulose without serious cellulose loss and degradation （ cellulose loss was less than 10% ） ; but also promote the subsequent lignin removal efficiency both in kraft pulping and oxygen delignification. Upon the above prehydrolysis conditions, the Kappa number of the prehydrolysis kraft pulp decreased to 16.3 and the final Kappa number of the oxygen delignified pulp lowered to 2.8. Alternatively, extensive prehydrolysis could retard the lignin removal and even cause difficulties in the kraft pulping process, indicating as high Kappa number of the pre- hydrolysis kraft pulp. Although the extensive prehydrolysis had an obvious inhibition effects on the subsequent kraft pulping, the lignin removal was still substantial during the oxygen delignification process; revealing that prehydroly- sis was more critical for kraft pulping than oxygen delignification.