Department of Chemical Engineering, Isfahan University of Technology, Isfahan, 8415683111, Iran.
Industrial Biotechnology Group, Research Institute for Biotechnology and Bioengineering, Isfahan University of Technology, Isfahan, 8415683111, Iran.
Appl Microbiol Biotechnol. 2018 Apr;102(7):3425-3438. doi: 10.1007/s00253-018-8833-8. Epub 2018 Feb 19.
Besides free sugars, sweet sorghum stalks contain cellulose and hemicellulose that can be used for biofuel production. The pretreatment of stalks without the extraction of free sugars is more complicated than typical lignocelluloses, because of the degradation of free sugars during most pretreatment processes. In this study, the bioconversion of sweet sorghum stalks into biogas and bioethanol was studied using an improved organosolv pretreatment within a biorefinery framework. The organosolv pretreatment was developed using an aqueous solution of ethanol (EtOH) and isopropanol (IPOH). The process was optimized to obtain a liquor containing free sugars with the least sugar degradations together with a highly degradable solid fraction. The liquor was subjected to anaerobic digestion for biomethane production, while the solid was used for ethanol production via simultaneous saccharification and fermentation (SSF). The most influencing pretreatment parameters, i.e., temperature, time, alcohol to water ratio, EtOH to IPOH ratio, and the presence or absence of sulfuric acid (as a catalyst), were adjusted to achieve the highest yields of bioconversion. The maximum methane and ethanol production yields of 271.2 mL CH/g VS and 87.8% (equal to the gasoline equivalent of 0.170 and 0.241 L/kg, respectively) were achieved from the liquor and pretreated solid, respectively; however, they were obtained at different optimum conditions. Considering the biorefinery perspective, the highest gasoline equivalent of 0.249 L/kg was efficiently obtained from the whole process after pretreatment at 140 °C for 30 min using 60:20 EtOH/IPOH ratio in the presence of 1% sulfuric acid. Further analyses, including enzymatic adsorption/desorption, compositional analysis, FTIR, and SEM, were conducted to investigate the effects of this newly developed pretreatment on the substrate.
除了游离糖，甜高粱秸秆还含有纤维素和半纤维素，可用于生物燃料生产。与典型的木质纤维素相比，不提取游离糖的秸秆预处理更为复杂，因为游离糖在大多数预处理过程中会降解。在这项研究中，使用生物炼制框架内的改进的有机溶剂预处理法，将甜高粱秸秆生物转化为沼气和生物乙醇。有机溶剂预处理法使用乙醇（EtOH）和异丙醇（IPOH）的水溶液开发。该过程经过优化，以获得含有游离糖的液体，同时使糖降解最少，并且具有高可降解的固体部分。该液体经过厌氧消化生产生物甲烷，而固体则通过同步糖化和发酵（SSF）用于生产乙醇。最具影响力的预处理参数，即温度、时间、醇水比、EtOH/IPOH 比以及硫酸（作为催化剂）的存在或不存在，进行了调整，以实现最高的生物转化产率。从液体和预处理固体中分别获得了 271.2 mL CH/g VS 的最大甲烷和 87.8%的乙醇产率（分别相当于汽油当量的 0.170 和 0.241 L/kg）；然而，它们是在不同的最佳条件下获得的。从生物炼制的角度来看，在 140°C 下预处理 30 分钟，使用 60:20 EtOH/IPOH 比并添加 1%硫酸，从整个过程中获得了最高的汽油当量 0.249 L/kg。进一步的分析，包括酶吸附/解吸、成分分析、FTIR 和 SEM，用于研究这种新开发的预处理方法对底物的影响。
