Beyene Dawit, Chae Michael, Vasanthan Thava, Bressler David C
Biorefining Conversions and Fermentation Laboratory, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada.
Front Chem. 2020 Apr 22;8:323. doi: 10.3389/fchem.2020.00323. eCollection 2020.
Hydrothermal treatment of wood pulp at 150-225°C prior to acid hydrolysis was investigated in the context of isolating cellulose nanocrystals (CNCs). The objective was 2-folds as follows: (a) generating furfural as a value-added co-product; and (b) concentrating and forming new CNC precursors through thermal re-orientation of para-crystalline cellulose chains that will in turn improve CNC recovery and yield. Furfural yields up to 19 and 21% xylan conversion were obtained at 200 and 225°C hydrothermal treatments, respectively. In addition, these hydrothermal treatment conditions increased the crystallinity index of the pulp (77%) to 84 and 80%, respectively. Consequently, the CNC yield from hydrothermally treated wood pulp, when compared to untreated wood pulp, improved by up to 4- and 2-folds, respectively. An efficient acid hydrolysis process with yield improvements can translate to reduced CNC isolation and purification costs and increased production capacity. The qualities of the CNCs in terms of particle size and crystallinity were not affected due to hydrothermal treatment. However, the zeta potential, sulfur, hydrogen, and oxygen content of the CNCs were significantly lower at 225°C while carbon composition increased, and dark brown coloration was observed that indicates caramelization. This study demonstrates for the first time a novel biorefinery strategy that introduces hydrothermal treatment prior to acid hydrolysis to co-generate furfural and CNC with improved efficiency.
在分离纤维素纳米晶体（CNC）的背景下，研究了在酸水解之前于150 - 225°C对木浆进行水热处理。目的有两个：（a）生成糠醛作为增值副产品；（b）通过对亚结晶纤维素链进行热重排来浓缩并形成新的CNC前体，这反过来又会提高CNC的回收率和产率。在200°C和225°C水热处理下，分别获得了高达19%和21%的木聚糖转化率的糠醛产率。此外，这些水热处理条件分别将木浆的结晶度指数从77%提高到了84%和80%。因此，与未处理的木浆相比，水热处理木浆的CNC产率分别提高了4倍和2倍。一种具有产率提高的高效酸水解工艺可以转化为降低CNC的分离和纯化成本以及提高生产能力。水热处理并未影响CNC在粒径和结晶度方面的质量。然而，在225°C时，CNC的zeta电位、硫、氢和氧含量显著降低，而碳组成增加，并且观察到深褐色表明发生了焦糖化。本研究首次展示了一种新颖的生物精炼策略，即在酸水解之前引入水热处理以共同高效生成糠醛和CNC。
