Understanding the impact of steam pretreatment severity on cellulose ultrastructure, recalcitrance, and hydrolyzability of Norway spruce
Journal article, 2024

The efficient use of softwood in biorefineries requires harsh pretreatment conditions to overcome biomass recalcitrance. Following harsh pretreatments, the hemicellulose is solubilized. Here, we studied the material characteristics of Norway spruce following steam pretreatment at six different severities, relating chemical and structural information to the enzymatic hydrolyzability. Steam pretreatment conditions were defined by two different temperatures (180 °C and 210 °C), with and without the addition of various acids (CH3COOH, H3PO4, H2SO4, SO2). Structural knowledge of the streams is a cornerstone for developing an efficient saccharification process. This study combines advanced structural characterizations to gain fundamental understanding of the influence of severity of pretreatment on spruce. Structural knowledge is a cornerstone in developing an effective saccharification process by modulating pretreatment conditions and enzymes employed. Overall structural properties were assessed by scanning electron microscopy. The effect of stream pretreatment severity on lignin and lignin-carbohydrate bonds was investigated by two-dimensional heteronuclear single quantum correlation nuclear magnetic resonance. Finally, cellulose ultrastructure was studied by applying small/wide-angle X-ray scattering. The structural characteristics of the six pretreated softwood substrates were related to the enzymatic hydrolyzability. With increasing pretreatment severity, surface defibrillation, and lignin depolymeryzation were observed. Further, lignin-carbohydrate complexes signals were detected. Cellulose analysis revealed the rearrangement of microfibrils leading to the formation of larger microfibril aggregates. This microfibril rearrangement likely contributed to the observed increase in enzymatic hydrolysis yields as better enzyme accessibility resulted.

Softwood

Cellulose accessibility

SAXS/WAXS

Lignin carbohydrate bonds

SEM

2D HSQC-NMR

Author

Fabio Caputo

Chalmers, Life Sciences, Industrial Biotechnology

Basel Al-Rudainy

Institutionen för Kemiteknik

Polina Naidjonoka

Chalmers, Physics, Materials Physics

Wallenberg Wood Science Center (WWSC)

O. Wallberg

Institutionen för Kemiteknik

Lisbeth Olsson

Chalmers, Life Sciences, Industrial Biotechnology

Vera Novy

Wallenberg Wood Science Center (WWSC)

Chalmers, Life Sciences, Industrial Biotechnology

Biomass Conversion and Biorefinery

2190-6815 (ISSN) 2190-6823 (eISSN)

Vol. 14 21 27211-27223

Subject Categories

Materials Chemistry

Other Chemistry Topics

Condensed Matter Physics

DOI

10.1007/s13399-022-03405-0

More information

Latest update

11/22/2024