Cationic hemicelluloses are interesting polysaccharides derivatives for different industrial applications. Cationisation of hemicelluloses is usually performed in aqueous alcohol or in water in the presence of NaOH and 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHMAC) or 2,3-epoxypropyltrimethylammonium chloride (ETA) as etherifying agent yielding DS up to 1.6, depending on the conditions and hemicellulose type. In a previous studies, we have reported the optimization of hemicelluloses cationisation in aqueous media using ETA as cationic reagent. DS values from 0.1 to 1.3 have been obtained by varying reaction parameters. However, ETA is an expensive and potentially carcinogenic chemical. In order to increase the reaction efficiency and decrease the consumption of ETA, it is possible to perform the reaction in a solid state, by using a minimum amount of solvent. This type of process is currently used for the cationisation of starch. In this work, the cationisation of two hemicelluloses (a galactomannan and a xylan) was studied both in liquid and in solid phase. By this method, the reaction efficiency was significantly increased for all hemicellulose types, up to 90% in the case of xylan. The consumption of reagents was reduced by ten compared to the reaction in liquid phase, while comparable DS values are obtained. DS values of 0.10 to 0.30 were obtained for the xylan type, and up to 0.44 for the galactomannan. These values are in agreement with the ones typically used in most of applications targeted for theses cationic polysaccharides. By reducing the number of purification steps, the consumption of solvents is limited, and high mass yields are preserved. These obtained cationic derivatives were then tested as additives to pulp in order to increase the resistance of paper. The cationisation of hemicelluloses had a beneficial effect on the mechanical properties of paper, compared to the native polysaccharides. Cationic derivatives of DS 0.3 gave the best results for both polysaccharides, the galactomannan ones being more efficient than the xylan ones with 90% of increase for the burst index. Therefore, the solid process constitutes an excellent improvement in terms of economy, environmental and safety for the cationisation reaction of hemicelluloses, compared to the liquid process.

Hemicelluloses cationization: Comparison of liquid and solid phase preparation processes

253rd National Meeting (2017)

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