The European pulp and paper industries are facing the problem of competitiveness, due to the increased production of paper pulp in Asia and South America and the decrease in paper consumption. A solution is to include the concept of biorefinery in their process by the valorization of the non-cellulosic sugars and/or lignins that are excluded from wood in the paper mill process. The Pressurized Hot Water (PHW) extraction has been frequently studied for the extraction of hemicelluloses from lignocellulosic plants and has been integrated as a pretreatment of wood for the removal of hemicelluloses before pulp process like Kraft cooking. Nevertheless, under such conditions, other compounds are co-extracted mainly lignins or other phenolic compounds like tannins or lignins derivatives. The objective of this study was the comparison of extract compositions for different subcritical water extraction processes with four hardwood species: poplar, beech, oak and chestnut from south of France. Three different systems for PHW extraction were used: - A 250ml reactor for the determination of kinetics of extraction and physico-chemical properties. - A 8 liters pressurized reactor to perform a multistage discontinuous batch extraction with a kinetic monitoring. - A twin-screw extruder for a continuous extraction under thermomechanical effect. The experiments were carried out with temperature between 130°C and 170°C for L/S ratios between 3 and 6. During the extractions, the content of carbohydrates (xylose, glucose), tannins and lignin’s compounds were evaluated. Processes were compared in order to identify the best conditions of extraction for the main types of molecules. Results also allowed understanding the mechanisms of the lignocellulosic matrix solubilization in PHW conditions.

Co-extraction of hemicelluloses and polyphenolic compounds from four hardwood species using pressurized hot water: Influence of the process on extraction yields and mechanisms

253rd National Meeting (2017)

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