...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Agricultural and Food Chemistry >Dissolution Mechanism of Crystalline Cellulose in H3PO4 As Assessed by High-Field NMR Spectroscopy and Fast Field Cycling NMR Relaxometry
【24h】

Dissolution Mechanism of Crystalline Cellulose in H3PO4 As Assessed by High-Field NMR Spectroscopy and Fast Field Cycling NMR Relaxometry

机译：通过高场NMR光谱和快速场循环NMR弛豫法评估晶体纤维素在H3PO4中的溶解机理

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Many processes have been proposed to produce glucose as a substrate for bacterial fermentation to obtain bioethanol. Among others, cellulose degradation appears as the most convenient way to achieve reliable amounts of glucose units. In fact, cellulose is the most widespread biopolymer, and it is considered also as a renewable resource. Due to extended intra- and interchain hydrogen bonds that provide a very efficient packing structure, however, cellulose is also a very stable polymer, the degradation of which is not easily achievable. In the past decade, researchers enhanced cellulose reactivity by increasing its solubility in many solvents, among which concentrated phosphoric acid (H3PO4) played the major role because of its low volatility and nontoxicity. In the present study, the solubilization mechanism of crystalline cellulose in H3PO4 has been elucidated by using high- and low-field NMR spectroscopy. In particular, high-field NMR spectra showed formation of direct bonding between phosphoric acid and dissolved cellulose. On the other hand, molecular dynamics studies by low-field NMR with a fast field cycling (FFC) setup revealed two different H3PO4 relaxing components. The first component, described by the fastest longitudinal relaxation rate (R1), was assigned to the H3PO4 molecules bound to the biopolymer. Conversely, the second component, characterized by the slowest R1, was attributed to the bulk solvent. The understanding of cellulose dissolution in H3PO4 represents a very important issue because comprehension of chemical mechanisms is fundamental for process ameliorations to produce bioenergy from biomasses.
机译：已经提出了许多方法来生产葡萄糖作为细菌发酵的底物以获得生物乙醇。其中，纤维素降解似乎是获得可靠量的葡萄糖单位的最方便方法。实际上，纤维素是最广泛的生物聚合物，也被视为可再生资源。然而，由于延伸的链内和链间氢键提供了非常有效的堆积结构，因此纤维素也是非常稳定的聚合物，其降解不容易实现。在过去的十年中，研究人员通过增加其在许多溶剂中的溶解度来增强纤维素的反应性，其中浓磷酸（H3PO4）由于其低挥发性和无毒性而起着主要作用。在本研究中，已通过使用高场和低场NMR光谱阐明了H3PO4中结晶纤维素的增溶机理。特别地，高场NMR光谱显示磷酸和溶解的纤维素之间直接键合的形成。另一方面，通过低场NMR和快速场循环（FFC）装置进行的分子动力学研究揭示了两种不同的H3PO4弛豫成分。用最快的纵向弛豫速率（R1）描述的第一个组分分配给与生物聚合物结合的H3PO4分子。相反，第二组分的特征是R1最慢，归因于本体溶剂。对纤维素在H3PO4中溶解的理解是一个非常重要的问题，因为对化学机理的理解对于改善工艺过程以从生物质中产生生物能至关重要。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号