The Fate of 4-O-Methyl Glucuronic Acid in Hardwood Xylan during Alkaline Extraction

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• 作者：Christian Hutterer ; Karin Fackler ; Antje Potthast
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2017
• 出版时间：February 6, 2017
• 年：2017
• 卷：5
• 期：2
• 页码：1818-1823
• 全文大小：396K
• ISSN：2168-0485

文摘

Highly pure wood cellulose pulps are a prerequisite to the production of regenerated fibers and cellulose derivatives. Harsh treatments for their preparation promote the digestion of wood-derived impurities, but also cause substantial yield losses on cellulose. Kraft pulping technology offers the possibility to almost completely preserve cellulose integrity, but this also applies to hemicelluloses, which must be quantitatively removed to ensure stable rayon fiber production. Alkaline postextractions of paper pulps are able to selectively remove hemicellulose impurities without degrading cellulose. The xylan can be recovered as a polymer in neat form. Hardwood kraft pulps in particular show good applicability, as xylan is easily extractable by alkaline treatments. The present study was designed to profile xylan distribution in alkali-treated pulps using 4-O-methylglucuronic acid as a marker for xylan. Labeling the uronic acid with the fluorescence marker FDAM (9H-fluoren-2-yl-diazomethane) and subsequent size exclusion chromatography (SEC) allowed xylan profiling relative to the molar mass distribution of cellulose. The method revealed an enrichment of uronic acids in the cellulosic fraction with increasing alkalinity during pulp treatment. Additionally, side reactions could be visualized, as the labeling technique is very sensitive.