麦草碱法蒸煮中碱耗和木质素溶出的特征

The Characteristics of Alkali Consumption And Lignin Dissolution during the Alkaline Cooking of Wheat Straw

本文借助切分蒸煮过程的手段,系统地研究了麦草碱法蒸煮中碱耗的分配,以及木质素的溶出特征,同时还通过溶出粗木质素的组成分析,对麦草碱法蒸煮中限制蒸煮得率的因素作了探讨,结果表明:(1)蒸煮用碱主要消耗于蒸煮前期酸性级分的中和,以及蒸煮前期溶出物的后续反应,作用于木质素降解反应的碱耗仅占很小的比倒:(2)麦草的碱易溶半纤维素和LCC的存在,以及LCC的抗碱性降解的特性,是限制其蒸煮得率提高的主要因素;(3)麦草碱法蒸煮后期脱木质素的进行,以物理形式自然溶出为主、化学降解为辅,其中木质素的溶出孔道对后期脱木质素的进行不具有控制作用。

The characteristics of alkali consumption and lignin dissolution during the alkaline cooking of wheat straw were studied by means of two stage-cooking. And the factors which limit the pulp yield of cooking were also disscused. The results show that the alkali is mainly consumed for the reaction of acidic components and for the successive reaction of materials which dissolved in the early stage of cooking. The consumption of alkali for the degradation of lignin only accounts for a very small part The results also show that the existence of hemicellulose which is casly dissolving in alkali-solution and of lignin-carbohydrate-complex (LCC) which is alkali-degradation-resistant are the main factors limiting the pulp yield of cooking. And it was found that in the late stage of cooking, the dissolution of lignin is mainly physically and the lignin-degradation is less important. The pathway-limitation shows no remarkable inference on lignin dissloving.