收稿日期: 2015-09-17
网络出版日期: 2017-06-30
基金资助
国家自然科学基金面上资助项目(21571127)
Influence of hydrothermal pretreatment of corncob on structure of cellulose
Received date: 2015-09-17
Online published: 2017-06-30
针对预处理成本高、会产生二次污染、后续提纯除杂步骤复杂等问题, 在水热预处理条件下添加干冰作为辅助介质, 研究了操作条件(温度、处理时间和干冰添加量)对玉米芯中纤维素的解聚行为以及木质素脱除率的影响关系, 并采用傅里叶转换红外线光谱分析仪(Fourier transform infrared spectroscopy, FTIR)和X射线衍射(X-ray diffraction, XRD)进行分析, 得到了纤维素结构在预处理过程中的变化规律, 对优化预处理工艺有重要的理论指导意义.研究结果表明: 当温度超过160°C时纤维素无定型区域的链结构开始断裂; 当温度升高到180°C时纤维素聚合度(degree of polymerization, DP)急剧下降, 同时木质素去除率达到最高(31.6%). FTIR分析结果表明: 与预处理前相比, 预处理后纤维素中的C—O—C吸收峰减弱, 说明纤维素的糖苷键被破坏, 纤维素链发生了断裂. XRD分析结果表明: 在预处理过程中玉米芯中纤维素的结晶度增大, 说明在预处理过程中纤维素的无定型部分被脱除, 同时部分纤维素Ⅰ转化为纤维素Ⅱ.
张莉, 王征, 舒思韬, 郭晓亚 . 玉米芯水热预处理对纤维素结构的影响[J]. 上海大学学报(自然科学版), 2017 , 23(3) : 464 -472 . DOI: 10.12066/j.issn.1007-2861.1684
To solve the problem of high costs in pretreatment, secondary pollution and complicated subsequent purification, solid CO2 was added as an auxiliary medium under hydrothermal pretreatment conditions. The effects of operating conditions including temperature, time and the amount of solid CO2 on the cleavage behavior of cellulose and lignin removal were investigated. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to analyze the structural variation of cellulose, which had great significance of theoretic instruction to optimize the pretreatment process. The results show that cellulose chain cleavage basically occurs when the temperature exceeds 160°C. As temperature rises to 180°C, degree of polymerization (DP) decreases dramatically, and the removal of lignin reaches the highest (31.6%). From the analysis of FTIR, peaks associated with C—O—C bonds are weakened in pretreated samples, indicating that glycosidic bonds and chains of cellulose are broken down during the pretreatment process. Further analysis by XRD shows an increase in crystallinity of cellulose in pretreated corncob, indicating removal of the amorphous part of cellulose, and transition of cellulose Ⅰto cellulose Ⅱduring pretreatment.
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