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Comprehensive study on the effects of process parameters of alkaline thermal pretreatment followed by thermomechanical extrusion in sugar liberation from Eucalyptus grandis wood

  • Pablo Doménech ORCID logo EMAIL logo , Paloma Manzanares , Cristina Álvarez , Mercedes Ballesteros and Aleta Duque
From the journal Holzforschung


A combination of alkaline thermal pretreatment followed by thermomechanical extrusion was studied as a novel sequential pretreatment process for an effective breakdown of the lignocellulosic structure of Eucalyptus grandis wood (EW). The first step was studied by analysing the influence of two factors: the NaOH-to-dry biomass ratio or NaOH loading (NaOH/DM) and the liquid-to-solid ratio (L/S). Optimization of these two parameters provided good results in terms of enzymatic hydrolysis at 5% (w w−1) solids loading, obtaining a total sugar concentration of 24.9 g L−1 and a total sugar production of 36.9 g 100 g−1 raw EW after pretreating the biomass at 20% NaOH/DM and L/S = 1/1. The second step of extrusion, when followed by a final washing step, provided a significant increase in glucose and xylose production when working at 10% NaOH/DM. For a soda loading of 20%, there was a clear improvement in sugars conversion yield after extrusion and washing: 71% for glucan conversion and 89% for xylan.

Corresponding author: Pablo Doménech, Biofuels Unit, Energy Department – CIEMAT, Avda. Complutense 40, 28040, Madrid, Spain, E-mail:

Funding source: European Commission

Award Identifier / Grant number: 654365


The authors would like to thank the INIA (Uruguay) for kindly providing the eucalyptus biomass used for all experiments and Novozymes A/S (Denmark) for kindly providing the enzymatic cocktail used for saccharification.

  1. Author contribution: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: This work was carried out in the frame of the BABET-REAL5 Project. The project is co-funded by the European Union within the Horizon 2020 programme Grant Agreement No. 654365.

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.


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Received: 2020-03-11
Accepted: 2020-07-01
Published Online: 2020-08-19
Published in Print: 2021-03-26

© 2020 Walter de Gruyter GmbH, Berlin/Boston

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