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Fig. 3 Common linkages between monolignols identi fi ed in lignins. 51,52
linkages, Fig. 4 should only be taken as an illustrative example. The lignin macromolecule is polydisperse and may exhibit various linkages and functional groups. 4 In other words, lignin should be considered as statistical entities rather than distinct polymers.
2.2. Isolation of technical lignin Lignocellulosic biomass consists of cellulose (30 – 50%), hemi- cellulose (20 – 35%) and lignin (15 – 30%), where the lignin acts as a “ glue ” within the LCCs. 58,59 The actual lignin content of the biomass is highly in uenced by its botanical origin e.g. , 28 – 32%
Fig. 4 Adaptation of Adler's representation of softwood (spruce) lignin with color-coded monolignols: p -hydroxyphenyl (H-unit) in black, guaiacyl (G-unit) in blue and syringyl (S-unit) in red. 55
12532 | RSCAdv. , 2023, 13 , 12529 – 12553
© 2023 The Author(s). Published by the Royal Society of Chemistry
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