漆酶和木聚糖酶预处理对麦草浆漂白性能的影响

生物漂白主要目的在于通过对纸浆预处理,减少后续漂白时漂剂用量,降低漂白废水对环境污染,同时改善纸浆性能。通过漆酶/木聚糖酶体系(LXS)和重组木聚糖酶(X)对麦草浆预处理,比较它们对浆料脱木素能力和漂白性能的影响。结果表明:麦草浆经过两种酶预处理后,都能降低浆料卡伯值,而漆酶处理后降低的幅度更大,与原浆和木聚糖酶处理浆相比分别降低32.64%和6.47%,但是在木聚糖酶处理液中能检测到更多的还原糖;两种酶处理浆在后续漂白中漂白至与对照浆相近白度时均能节省50%漂剂用量,且能改善浆料物理强度;比较两种酶对浆料漂白性能的影响,则是在相同漂剂用量时木聚糖酶漂白浆的白度稍高,而浆料得率和强度稍低;两种酶处理浆料的纤维素结晶度测定表明酶处理前后浆料的纤维素的结晶结构没有明显的变化,而且纤维素的结晶度都有不同程度的提高。通过扫描电镜观察以及X射线光电子能谱(XPS)分析,从理论上说明两者脱木素的差异。

Effect of Laccase and Xylanase Pretreatment on Bleachability of Wheat Straw Pulp

The purpose of biobleaching is to reduce bleaching agent dosage in following bleaching process, to decrease environment pollution and to improve pulp properties by means of pulp enzymatic pretreatment. The effects of wheat straw pulp pretreatment with laccase/xylanase system （LXS） and recombinant xylanase （X） respectively on bleachability ofptLlp were compared in this paper. The results indicated as follows. The kappa number of pulps after pretreatment with laccase/xylanase system or recombinant xylanase decreased, but the kappa number of pulp pretreated with LXS decreased obviously. It decreased by 32.64% and 6.47% respectively compared with original pulp and X pretreated pulp. More reducing sugar content was determined in the solution pretreated with X. The chlorine dosage could be decreased by 50% after LXS or X pretreatment following bleaching process compared with control pulp at close brightness and the physical strength of pulps was improved. While effect of two enzymes on pulp laleachabilities was compared, the brightness of pulp pretreated with X was better, but the strength and yield of pulp were lower. The crystal structure of cellulose did not change after LXS and X pretreatment, at the same time the crystallinity of cellulose increased slightly. The scanning electron microscope （SEM） images and X-ray photoelectron spectroscopy （XPS） analysis of two enzym, es treatment pulps further explained theoretically the delignification difference between LXS and X pretreatment.