Green alkaline fractionation of sugarcane bagasse at cold temperature improves digestibility and delignification without the washing processes and release of hazardous waste

A response surface design was used to pretreat sugarcane bagasse (SB) with urea (U)/potassium hydroxide (K) at low temperatures. Alkaline pretreatment can increase the digestibility of biomass by removing lignin. However, this pretreatment has common issues, such as high-water consumption and liquid waste generation. To address these issues, this study was conducted to perform the UK pretreatment without washing steps. Under optimized pretreatment condition (-20 degrees C, 7.5 % UK), hemicellulose and lignin removal were increased approximately by 1.4 (26.18-18.86 %) and 1.7 folds (21.25 % to 12.43 %), respectively, while cellulose increased by 1.6-fold (42.39-68.34 %) as compared to control. This enhanced the enzymatic hydrolysis by 3.16-fold (75.15 %). In addition, physicochemical analyses revealed that U facilitates fiber opening, reduces the crystallinity index of cellulose (55.06-49.03 %), and prevents lignin droplet formation from adhering to cellulose. Hence, UK pre-treatment can be a promising pretreatment technology for lignocellulosic valorization towards biorefinery without any washing in restoring the liquid substances.

Automated summary

A response surface design was used to pretreat sugarcane bagasse (SB) with urea (U) and potassium hydroxide (K) at low temperatures. The optimized pretreatment condition (-20 degrees C, 7.5% UK) resulted in increased removal of hemicellulose and lignin, as well as an increase in cellulose content compared to the control. The UK pretreatment also improved enzymatic hydrolysis and exhibited potential as a pretreatment technology for lignocellulosic valorization.