Unveiling Modifications of Biomass Polysaccharides during Thermal Treatment in Cholinium Chloride : Lactic Acid Deep Eutectic Solvent


A deep analysis upon the chemical modifications of the cellulose and hemicelluloses fractions that take place during biomass delignification with deep eutectic solvents (DES) is lacking in literature, being this a critical issue given the continued research on DES for this purpose. This work intends to fill this gap by disclosing a comprehensive study on the chemical modifications of cellulose (microcrystalline cellulose and bleached kraft pulp) and hemicelluloses (xylans) during thermal treatment (130 degrees C) with cholinium chloride/lactic acid ([Ch]Cl/LA) at molar ratio 1 : 10, one of the best reported DES for biomass delignification. The obtained data revealed that [Ch]Cl/LA (1 : 10) has a negative impact on the polysaccharides fractions at prolonged treatments (>4 h), resulting on substantial modifications including the esterification of cellulose with lactic acid, shortening of fibers length, fibers agglomeration and side reactions of the hemicelluloses fraction (e. g., humin formation, lactic acid grafting). Wood delignification trials with [Ch]Cl/LA (1 : 10) at the same conditions also corroborate these findings. Moreover, the DES suffers degradation, including the formation of lactic acid derivatives and its polymerization. Therefore, short time delignification treatments are strongly recommended when using the [Ch]Cl/LA DES, so that a sustainable fractionation of biomass into high quality cellulose fibers, isolated lignin, and xylose/furfural co-production along with solvent recyclability could be achieved.




Chemistry, Multidisciplinary; Green & Sustainable Science & Technology


Morais, ES; Lopes, AMD; Freire, MG; Freire, CSR; Silvestre, AJD

nossos autores


This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the FCT/MCTES. The authors would like to thank the members of the ISPT Deep Eutectic Solvents in the pulp and paper industry consortium for their financial and in-kind contribution. This cluster consists of the following organizations: Altri-Celbi, Buckman, Crown Van Gelder, CTP, DS Smith Paper, ESKA, Essity, Holmen, ISPT, Mayr-Melnhof Eerbeek, Metsa Fiber, Mid Sweden University, Mondi, Omya, The Navigator Company, Sappi, Essity, Smurfit Kappa, Stora Enso, Eindhoven University of Technology, University of Aveiro, University of Twente, UPM, Valmet Technologies Oy, Voith Paper, VTT Technical Research Centre of Finland Ltd, WEPA and Zellstoff Pols. Furthermore, this project received funding from the Bio-Based Industries Joint Undertaking under the European Union's Horizon2020 research and innovation programme under grant agreement Provides No. 668970 and was co-funded by TKI E&I with the supplementary grant TKI-Toeslag for Topconsortia for Knowledge and Innovation (TKIs) of the Ministry of Economic Affairs and Climate Policy. The work was also funded by FCT/MCTES through the projects DeepBiorefinery (PTDC/AGR-TEC/1191/2014) and MultiBiorefinery (POCI-01-0145-FEDER-016403). The NMR spectrometers are part of the National NMR Network (PT NMR) and are partially supported by Infrastructure Project No 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). E. S. M. acknowledges FCT/MCTES for a PhD grant (SFRH/BD/129341/2017). A. M. d. C. L. acknowledges ISPT for funding his postdoctoral grant.

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