Green and efficient fractionation of bamboo biomass via synergistic hydrothermal-alkaline deep eutectic solvents pretreatment: Valorization of carbohydrates

The development of green and efficient pretreatment strategies for renewable biomass valorization is required and remains challenging. In this study, a green, efficient, and profitable pretreatment strategy using hydrothermal combined with alkaline deep eutectic solvents (HT-ADESs) was developed for the fractionation and valorization of bamboo biomass. The results demonstrated that HT pretreatment not only selectively valorized hemicellulose into functional xylooligosaccharides (XOS), accounting for 65.9% of hydrolyzed xylan, but also facilitated the subsequent delignification with ADESs. Furthermore, 29% of hemicellulose was recovered from the prehydrolyzate, revealing a branched structure of O-acetyl-4-O-methyl-glucurono-& beta;-(1 & RARR; 4)-ᴅ-xylan. Following delignification with choline chloride/monoethanolamine containing 25 wt% peroxide, up to 98.4% glucose yield and 99.2% xylose yield were realized by enzymatic hydrolysis of pretreated residue, which were significantly higher than those of unpretreated bamboo (14.6% and 8.1%, respectively). The incorporation of an appropriate amount of water or peroxide into pure ADES facilitated lignin fractionation and reduced biorefinery costs. Overall, this work presented a promising pathway that could valorize 1 kg of dry bamboo into 490 g of fermentable sugars and 78 g of XOS, accompanied by 54 g of hemicellulose and 200 g of lignin fractions.

Automated summary

In this study, a green, efficient, and profitable pretreatment strategy using hydrothermal combined with alkaline deep eutectic solvents (HT-ADESs) was developed for the fractionation and valorization of bamboo biomass. The results showed that the strategy could selectively valorize hemicellulose into functional xylooligosaccharides (XOS) and facilitate subsequent delignification to achieve high glucose and xylose yields.