E－An－76在桦木KP浆及麦草Soda－AQ浆CEH三段漂中的应用

BIOLEACHING OF BIRCH KP AND WHEAT STRAW SODA-AQ PULPS WITH E-An-76

研究了半纤维素酶Ｅ－Ａｎ－７６作为漂白助剂对桦木硫酸盐浆及麦草烧碱蒽醌浆ＣＥＨ三段漂的影响。结果表明：桦木ＫＰ浆用Ｅ－Ａｎ－７６预处理后再经ＣＥＨ三段漂，其白度明显高于相同用氯量下未用酶预处理的漂白浆。另一方面在保持白度不变的情况下酶处理浆的漂白可节省近５０％的用氯量。麦草Ｓｏｄａ－ＡＱ浆经Ｅ－Ａｎ－７６预处理后再经ＣＥＨ三段漂与酶未处理浆的ＣＥＨ三段漂比较亦可明显提高白度，但得率下降严重。通过对桦木ＫＰ浆酶解液中还原糖以及单糖组成分析，发现浆中再沉积或回吸的木聚糖在Ｅ－Ａｎ－７６助剂漂白中起着重要作用。

E-An-76 is a hemicellulase preparation from Aspergillus niger which has a xylanase activity of235 IU/mL and contains low levels of cellulase activities. The potential of this hemicellulase as a bleachingbooster in CEH process was studied.The results showed that birch KP pretreated with E-An-76 beforeCEH process could get a brightness 6.8%higher than that of the untreated one under the same chlorinedosage,or it can save nearly 50%of chlorine consumption for the same brightness.The yield decreasedslightly with no adverse effect on strength properties,Wheat straw pulp pretreated with E-An-76 beforeCEH process could get a brightness about 11%higher than the control's,but the yield decreased signifi-cantly. It was found by studying the reducing sugars and carbonhydrate composition in birch KP hydrolysatedegraded by E-An-76,that the reprecipitated or readsorbed xylan appeared to play an important role in themechanism of hemicellulase-aided bleaching.