Abstract:

In order to overcome the defects of separation of three components of plant stalk lignin and hemicellulose and cellulose in the high temperature and high pressure harsh conditions and the low purity and recovery rate of separation of the components, this stady was first pretreated the corn stalk  by using of ethanol and nitric acid under atmospheric condition. After that, it was steamed in the dilute alkali solution and treated by H2O2. The optimized scheme of separating and purifying cellulose from corn stalk was provided by the orthogonal test. It included the removal of lignin and hemicellulose in corn stalk. For the lignin its removal rate was 76.3% and recovery rate was 44.5% when solid-to-liquid ratio was 1∶14, the ratio of nitric acid:ethanol was 1∶2 (v/v), and the reaction time was 3 h at 76 ℃. For the hemicellulose its removal ratio was 98.8% when the concentration of the solution NaOH was 4%, solid-to-liquid ratio was 1∶40, temperature was at 95 ℃, and the reaction time was 2.5 h. For the hemicellulose its recovery rate was 66.0% when the ratio of colatuie-to-ethanol was 1∶0.8 (v/v), the settling time was 2 h and pH 7. The content of the obtained cellulose reachs to 99.28% and the yield was 59.7% after being treated for 6 h by 2.5% H2O2 solution at the temperature of (46±1)℃, solid-to-liquid ratio of 1∶30 and pH 11.5. Above result showed that the method had some merits, including mild reaction conditions, environment friendly, and should be a new way of classification using corn stalk.

Key words: lignin, hemicellulose, cellulose, corn stalk

摘要：

针对分离植物茎秆中的木质素、半纤维素和纤维素需高温和高压处理的苛刻条件以及所得组分纯度和回收率均较低的缺陷,采用乙醇和硝酸相结合的方法对玉米秸秆在常压下进行预处理,经稀碱溶液蒸煮及过氧化氢处理,实现高效分离和回收木质素、半纤维素和纤维素组分的目的。正交试验确定的最佳条件为：固液比1∶14、硝酸与乙醇体积比1∶2、76℃下反应3 h,原料的木质素脱除率达76.3%,木质素回收率为44.5%；预处理后的原料以4% NaOH为溶剂、固液比1∶40、95℃下蒸煮2.5 h,其半纤维素脱除率98.8%,半纤维素回收率达66.0%（滤液∶乙醇1∶0.8、pH 7、沉淀2 h）；粗纤维素以2.5%H2O2为溶剂、固液比1∶30、pH 11.5、（46±1）℃下处理6 h,其纤维素纯度99.28%,回收率59.7%。该方法具有工艺条件温和及绿色环保等优势,为玉米秸秆的分级利用提供了一条新的途径。

关键词: 木质素, 半纤维素, 纤维素, 玉米秸秆