杨木废弃物稀酸水解预处理条件的响应面优化

以聚糖类转化率为考核指标,探讨了杨木废弃物稀酸水解预处理物料的适宜颗粒尺寸范围,并用响应面实验设计优化了稀酸水解条件.结果表明,稀酸水解预处理物料的适宜颗粒尺寸为0.075~0.096 mm,稀硫酸水解的优化工艺条件为:固液比1:10,温度158 ℃,时间5 min,硫酸质量分数2.5%.在此优化条件下,聚糖类转化率为59.23%.稀酸水解液的高效液相色谱分析表明,水解液主要成分为木糖(29.897 g/L),占总糖量的64.8%,其次为葡萄糖(8.748 g/L),占总糖量的18.9%,稀酸水解单糖继续降解较少.SEM形貌和XRD分析表明,水解残渣的纤维结构破坏明显,其结晶度由原料的57.45%降低到47.37%,该稀酸水解残渣存在通过酶解和发酵制备生物乙醇的可能性.

Optimization of Dilute-sulfuric Acid Pretreatment of Poplar Residues by Using Response Surface Design

The dilute acid hydrolysis was applied to the poplar residues conversion,and the polysaccharides conversion rate was figured out for the assessment of conversion efficiency.Several parameters concerned with the conversion efficiency,such as bio-mass substrate size,dosage of acid,hydrolysis pressure (or temperature) and reaction time were investigated.The response surface experimental design was used to optimize the dilute acid hydrolysis conditions.It was proposed that proper particle sizes were 0.075 to 0.096 mm and the optimal conditions for the dilute sulfuric acid hydrolysis were illustrated as the solid to liquid ratio of 1:10,temperature of 158 ℃,reaction time of 5 min,and the fraction of sulfuric acid of 2.5%.Under the optimal conditions, the polysaccharides conversion rate was up to 59.23%.The HPLC analysis of hydrolyzates showed that the main component was xylose (29.897 g/L) with a content of 64.8% in total sugar amount,and the second one was glucose (8.748 g/L) with a content of 18.9%.Less monosaccharides further degraded in the dilute acid hydrolysis.The SEM observation and XRD analysis of substrate samples before and after the dilute acid hydrolysis showed that the fiber structure of the hydrolysis residue was damaged obviously,and the crystallinity decreased from 57.45% of the raw material to 47.37% of the hydrolysis residue.It could be expected that the hydrolysis residue be utilized to make bioethanol by enzymatic hydrolysis and fermentation.