Textile and Paper Engineering Department, ETSEIAT, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain.
J Hazard Mater. 2010 May 15;177(1-3):586-92. doi: 10.1016/j.jhazmat.2009.12.073. Epub 2009 Dec 23.
Using an enzyme-based stage involving a xylanase (X) or laccase (as part of a laccase-mediator system, L) in a bleaching process can help reduce reagent consumption and hence its environmental impact. In this work, both types of enzymes were applied to eucalypt pulp. The influence of process variables in the laccase-mediator treatment (viz. laccase dose, HBT dose and reaction time) was assessed by using a three-variable sequential statistical plan. The effect of a pretreatment with X on the previous variables was also assessed. Kappa number and brightness models for the L stage and XL sequence were found to perform disparately, which suggests the formation of lignin derivatives interfering with brightness measurements. The L system oxidized readily accessible lignin within the first hours of treatment and affected the contents in cellulose and hexenuronic acids (HexA) of the resulting pulp. Xylanase facilitated access of the laccase-HBT system to lignin and HexA in cellulose fibres. The L treatment increased effluent properties such as Microtox toxicity, COD and colour, and led to strong inactivation of the enzyme. The increased toxicity of the effluents was due to HBT; based on statistical data, however, the effect can be reduced by lowering the mediator dose.
在漂白过程中使用基于酶的阶段，涉及木聚糖酶 (X) 或漆酶（作为漆酶-介体系统的一部分，L），可以帮助减少试剂消耗，从而减少其对环境的影响。在这项工作中，这两种酶都应用于桉树纸浆。通过使用三变量序贯统计计划评估了漆酶-介体处理（即漆酶剂量、HBT 剂量和反应时间）中过程变量的影响。还评估了 X 预处理对先前变量的影响。发现 L 阶段和 XL 序列的卡帕数和亮度模型表现不同，这表明形成了干扰亮度测量的木质素衍生物。L 系统在处理的最初几个小时内容易氧化木质素，并影响所得纸浆中纤维素和己糖醛酸 (HexA) 的含量。木聚糖酶促进漆酶-HBT 系统进入纤维素纤维中的木质素和 HexA。L 处理增加了废水的特性，如 Microtox 毒性、COD 和颜色，并导致酶的强烈失活。废水毒性增加是由于 HBT；然而，根据统计数据，通过降低介体剂量可以降低这种影响。
