Autohydrolysis is the chemical-free and environmentally friendly pretreatment technology, which leads to lignin and polysaccharide dissolutions in hydrolysate. Lignin and carbohydrates presented in hydrolysates can be used for manufacturing value-added products. However, the direct conversion of lignocellulosic materials present in hydrolysates to value-added products is expensive due to their low concentrations in the hydrolysates.<br/>In this study, the effect of autohydrolysis parameters on the properties, structure and composition of lignocelluloses extracted from softwood chips via flow through autohydrolysis pretreatment was investigated. To isolate lignocellulosic materials from hydrolysates, acidification and ethanol precipitation were employed. The highest temperatures applied in the autohydrolysis process were found to yield the maximum removal of lignin from wood; whereas, prolonged hydrothermal treatment increased the removal of hemicelluloses from wood. In addition, it was discovered that a low flow velocity led to higher lignocellulose removals. However, at a high liquid flow rate, hemicelluloses with larger molecular weights (Mw) were extracted. Gel permeation chromatography (GPC) analysis revealed the presence of lignin-carbohydrate complexes (LCC) in the hydrolysates. In addition, LCCs were also detected in the precipitates generated via acidification and ethanol treatment, but their removals depended on the hydrolysis conditions. The isolated material produced from hydrolysates due to ethanol or acid addition showed approximately twice as much heat capacity values as that of dried hydrolysates. The <sup>1</sup>H-NMR analysis revealed that the extracted materials via acidification contained more methoxy groups and less cross-linking than those present in hydrolysates. These results suggested that the materials obtained after acid or ethanol treatment of hydrolysates could be considered as additives for heat-resistant biopolymers or hemicellulose-based films, respectively.

Lignocellulosic materials in hydrolysis liquors: Isolation and properties

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.