麦草室温碱提取木质素、LCC级分程序分离及其组成特性

采用酸化沉淀法程序分级分离室温麦草碱抽提液中木质素、木质素-碳水化合物复合体(LCC),得到了pH值10.5、9.0和2.0三个级分。pH值10.5级分得率较高,为12.24%,该组分含有大量的碳水化合物,可能是以水不溶性LCC为主。随着pH值的降低,级分中的木质素含量逐渐增加,碳水化合物含量逐渐减少,pH值9.0和2.0组分均是以木质素为主。pH值2.0级分中碳水化合物含有较多的阿拉伯糖和半乳糖,该级分中LCC组成与pH值10.5和9.0级分LCC组成可能不同。抽提液中的SiO2大部分沉淀在pH值10.5和9.0级分中,pH值9.0级分中灰分质量分数高达13.29%。酸化沉淀程序分离法是一种分级分离麦草碱抽提液中木质素、LCC的有效方法。

The Fractionation and Composition Properties of Wheat Straw Lignin and LCC Extracted by Alkaline Solution at Ambient Temperature

Acid precipitation method was used for fractionation and purification of alkali extraction lignin and lignin-carbohydrate complexes(LCC) from wheat straw at ambient temperature.Three fractions of pH 10.5,pH 9.0 and pH 2.0 were obtained respectively.The yeild of pH 10.5 fraction was 12.24 %.It consisted of and large amounts of carbohydrate which might be preci-pitated as water-insoluble LCC.The lignin content in the fractions reduced with the decreasing pH.pH 9.0 and pH 2.0 fractions mainly consisted of lignin.However,the monosaccharide composition of pH 2.0 fraction is different from that of the pH 10.5 and pH 9.0 fractions.There are more arabinose and galactose in pH 2.0 fraction.SiO2 in the extracted liquor were almost precipitated into the pH 10.5 and pH 9.0 fractions.The ash content in pH 9.0 fraction was up to 13.29 %.Acid precipitation method is a useful one for fractionation of the lignin and LCC from alkali extraction liquor.