University of British Columbia, Department of Chemical and Biological Engineering, Vancouver, BC, Canada V6T 1Z3.
Bioresour Technol. 2010 Apr;101(7):2267-72. doi: 10.1016/j.biortech.2009.10.090. Epub 2009 Dec 16.
Recovered fibre from pulp mills represents a potentially significant feedstock for conversion to ethanol. Enzymatic hydrolysis of untreated recovered fibre (86.5 Kappa, 13% lignin) resulted in a hexose yield of approximately 23%, which highlighted the need for an effective pretreatment. Recovered fibre was pretreated as a substrate for enzymatic hydrolysis using oxygen delignification. An experimental design was used to optimize temperature (90-150 degrees C), caustic loading (2-10%), and reaction time (20-60 min). The post-delignification Kappa values ranged from 76.7 (11.5% lignin) under the mildest pretreatment conditions, to 20 (3% lignin) under the most severe pretreatment conditions. The effect of caustic load appears to have an increased effect at higher temperatures, with the Kappa numbers ranging from 76.7 (90 degrees C, 2% caustic, 20 min) to 56.0 (150 degrees C, 2% caustic, 20 min) and from 64.7 (90 degrees C, 10% caustic, 20 min) to 38.0 (150 degrees C, 10% caustic, 60 min). These changes in Kappa number reflect changes in the lignin fraction of 3.1% and 4%, respectively. Increasing the caustic load from 2% to 10% decreased the oxygen delignification yield from 93.5% to 87.9% at 90 degrees C and 20 min reaction time, and 80.3% to 74.7% at 150 degrees C. The effect of time on oxygen delignification yield was found to be most significant in the first twenty minutes, which correlates with the drop in Kappa number that was observed. The pretreated fibre was subjected to enzymatic hydrolysis using commercial enzymes Celluclast (80FPU/mL, 20.1CBU/mL) and Novozym (640.5 CBU/mL). A series of enzyme loadings ranging from 19 to 77 FPU/g were utilized on solids loading ranging from 20 to 100g (dry fibre)/L. Based on the pretreatment and hydrolysis results an empirical model was developed that can predict hydrolysis sugar concentrations based on the Kappa number, enzyme loading, and initial recovered fibre concentration.
从纸浆厂回收的纤维代表了一种有潜力的重要原料，可用于转化为乙醇。未经处理的回收纤维（卡伯值 86.5，木质素含量 13%）的酶解产生约 23%的己糖产率，这突出表明需要进行有效的预处理。回收纤维作为酶解的底物进行预处理，采用氧脱木质素法。使用实验设计优化温度（90-150°C）、碱用量（2-10%）和反应时间（20-60 分钟）。脱木质素后的卡伯值范围从最温和预处理条件下的 76.7（木质素含量 11.5%）到最苛刻预处理条件下的 20（木质素含量 3%）。碱用量的影响似乎在较高温度下有更大的影响，卡伯值范围从 76.7（90°C，2%碱，20 分钟）到 56.0（150°C，2%碱，20 分钟）和 64.7（90°C，10%碱，20 分钟）到 38.0（150°C，10%碱，60 分钟）。这些卡伯值的变化反映了木质素分数的变化，分别为 3.1%和 4%。在 90°C 和 20 分钟的反应时间下，将碱用量从 2%增加到 10%，会使氧脱木质素的产率从 93.5%降低到 87.9%，而在 150°C 时，产率从 80.3%降低到 74.7%。在 20 分钟内，氧脱木质素产率受时间的影响最为显著，这与观察到的卡伯值下降有关。预处理后的纤维用商业酶制剂 Celluclast（80FPU/mL，20.1CBU/mL）和 Novozym（640.5 CBU/mL）进行酶解。在固体负荷为 20-100g（干纤维）/L 的范围内，利用 19-77FPU/g 的一系列酶负荷进行了一系列实验。根据预处理和水解结果，开发了一个经验模型，可以根据卡伯值、酶负荷和初始回收纤维浓度预测水解糖浓度。
