Abstract:

The efficient conversion of hemicellulose is a key step in improving the utilization of all components of sweet sorghum bagasse. Sweet sorghum bagasse was pretreated by subcritical hydrolysis. The effects of different reaction temperature (160-200℃) and reaction time (10-60 min) on the yield of xylose(C-5 sugar) and byproducts were investigated by subcritical hydrothermal pretreatment. The experimental conditions were described by intensity factor. The effects of various organic acids on the subcritical hydrolysis of hemicellulose, including acetic acid, lactic acid and acetic acid+lactic acid were further investigated. The results showed that the maximum xylose concentration was 4.79 g·L^-1at the severity of 3.96(180℃, 40 min), during the subcritical hydrothermal pretreatment without added acid. The addition of organic acids could enhance the hydrolysis reaction and increase xylose concentration. Compared to the treatment with acetic acid or lactic acid alone, the combined use of acetic acid and lactic acid can effectively promote the degradation of hemicellulose and inhibit the formation of by-products. The maximum xylose concentration was 7.92 g·L^-1, which was obtained at 180℃, for 40 min, and with the addition of 1%(mass) acetic acid+lactic acid(lactic acid:acetic acid=6:4).

Key words: subcritical water, hydrolysis, hydrothermal, organic acids, biomass, sweet sorghum bagasse, hemicellulose, xylose

摘要：

半纤维素的高效转化是提高甜高粱渣原料全组分利用的关键技术之一。采用亚临界水热预处理方法，并将强度因子R₀引入研究过程，考察了不同温度（160~200℃）和反应时间（10~60 min）对甜高粱渣水解反应的影响。在这基础上，进一步考察了多种有机酸（乳酸、醋酸及乳酸+醋酸）对亚临界水解效果的影响。实验表明，当强度因子lgR₀=3.96（180℃，40 min）时，采用不外加酸的亚临界水热预处理工艺得到的最大木糖浓度为4.79 g·L^-1；有机酸的加入可强化水解反应，提高木糖浓度；与单一乳酸或醋酸处理方法相比，加入同浓度的乳酸+醋酸既可以促进半纤维素水解，又可以抑制副产物生成；在温度180℃，时间40 min，乳酸+醋酸（乳酸：醋酸=6：4）的浓度1%（质量）的条件下，木糖浓度为7.92 g·L^-1。

关键词: 亚临界水, 水解, 水热, 有机酸, 生物质, 甜高粱渣, 半纤维素, 木糖