杨木半纤维素在乙酸-乙酸钠缓冲体系预水解过程中的溶出规律

Dissolution of Poplar Hemicelluloses during Pre-hydrolysis in Acetic Acid-sodium Acetate Buffer

中文关键词:  杨木  乙酸-乙酸钠缓冲溶液  预水解  单糖  低聚糖

Key Words:poplar chip  acetic acid-sodium acetate buffers  pre-hydrolysis  monosaccharides  oligosaccharides

中文摘要:

      研究了乙酸-乙酸钠缓冲体系对杨木木片进行预水解过程中半纤维素的溶出规律。结果表明,缓冲溶液浓度(50～150 mmol/L)对半纤维素溶出的影响较小,而体系pH值(3.0～4.2)影响显著。随着预水解体系pH值的降低,水解液中总糖和单糖含量逐渐增加,pH值为 3.4时低聚糖含量达最大值。与以水为介质的热水预水解相比,乙酸-乙酸钠缓冲体系可促进半纤维素溶出,抑制糖类物质(尤其是单糖)的进一步降解,可获得更多的低聚糖和单糖。在缓冲溶液浓度100 mmol/L、pH值 3.4的优化条件下,乙酸-乙酸钠缓冲体系预水解液中低聚糖和单糖含量分别为6.47 g/L和2.47 g/L,降解产物乙酸和糠醛的含量分别比热水预水解减少了46%和47%。

Abstract:

      The dissolution of poplar hemicelluloses during pre-hydrolysis in acetic acid-sodium acetate (AASA) buffer was studied in this work.The results showed that the dissolution of hemicellulose was significantly depended on the buffer pH from 3.0 to 4.2,but was less affected by the buffer concentration from 50 mmol/L to 150 mmol/L.It was observed that both total sugar and monosaccharide contents in pre-hydrolysis liquor (PHL) increased with the decreasing of pH,and the highest oligosaccharides content was obtained at pH 3.4.Compared to hydrolysis only using hot water,pre-hydrolysis with AASA buffer promoted the dissolution of the hemicelluloses and inhibited the degradation of carbohydrate,especially monosaccharides,and consequently lead to higher yield of oligosaccharides and monosaccharides.At the optimized pH of 3.4 and buffer concentration of 100 mmol/L,the dissolution of hemicellulose resulted in 6.47 g/L oligosaccharides and 2.47 g/L monosaccharides,while the degradation products in PHL,acetic acid and furfural were reduced by 46% and 47% respectively comparing with hot water hydrolysis.