Laboratory of Applied Chemistry, Department of Chemistry, University of Jyväskylä, P.O. Box 35, FI-40014, Finland.
Laboratory of Applied Chemistry, Department of Chemistry, University of Jyväskylä, P.O. Box 35, FI-40014, Finland.
Spectrochim Acta A Mol Biomol Spectrosc. 2017 Sep 5;184:184-190. doi: 10.1016/j.saa.2017.05.010. Epub 2017 May 5.
Hot-water and dilute sulfuric acid pretreatments were performed prior to chemical pulping for silver/white birch (Betula pendula/B. pubescens) and Scots pine (Pinus sylvestris) chips to determine if varying pretreatment conditions on the original wood material were detectable via attenuated total reflectance (ATR) infrared spectroscopy. Pretreatment conditions varied with respect to temperature (130°C and 150°C) and treatment time (from 30min to 120min). The effects of the pretreatments on the composition of wood chips were determined by ATR infrared spectroscopy. The spectral data were compared to those determined by common wood chemistry analyses to evaluate the suitability of ATR spectroscopy method for rapid detection of changes in the wood chemical composition caused by different pretreatment conditions. In addition to determining wood species-dependent differences in the wood chemical composition, analytical results indicated that most essential lignin- and carbohydrates-related phenomena taking place during hot-water and acidic pretreatments could be described by applying this simple spectral method requiring only a small sample amount and sample preparation. Such information included, for example, the cleavage of essential lignin bonds (i.e., mainly β-O-4 linkages in guaiacyl and syringyl lignin) and formation of newly condensed lignin structures under different pretreatment conditions. Carbohydrate analyses indicated significant removal of hemicelluloses (especially hardwood xylan) and hemicelluloses-derived acetyl groups during the pretreatments, but they also confirmed the highly resistant nature of cellulose towards mild pretreatments.
热水和稀硫酸预处理在化学制浆之前进行，以确定银/白桦（Betula pendula/B. pubescens）和欧洲赤松（Pinus sylvestris）木片的原始木材材料上的不同预处理条件是否可以通过衰减全反射（ATR）红外光谱法检测。预处理条件因温度（130°C 和 150°C）和处理时间（30 分钟至 120 分钟）而异。ATR 红外光谱法测定了预处理对木片成分的影响。将光谱数据与常见木材化学分析结果进行了比较，以评估 ATR 光谱法用于快速检测不同预处理条件引起的木材化学成分变化的适用性。除了确定木材化学组成中与木材种类有关的差异外，分析结果表明，通过应用这种仅需要少量样品和样品制备的简单光谱方法，可以描述在热水和酸性预处理过程中发生的大多数与木质素和碳水化合物有关的重要现象。例如，包括必需木质素键（即愈创木基和紫丁香基木质素中的主要β-O-4 键）的断裂以及在不同预处理条件下形成新的缩合木质素结构。碳水化合物分析表明，在预处理过程中半纤维素（特别是硬木木聚糖）和半纤维素衍生的乙酰基大量去除，但它们也证实了纤维素对温和预处理的高度抗性。
