Pretreatment of Camellia oleifera shell by ethanolamine-based solvents for selective delignification and enhanced enzymatic saccharification

Fruit shell biomass is an agricultural waste that could be valorised into various value-added chemicals. However, the intertwined structure between lignin and holocellulose limits free sugar generation for further fermentation, requiring efficient pretreatment for selective delignification. We pretreated Camellia oleifera shell by ethanolamine-based solvents (binary deep eutectic solvents and single ethanolamine or its derivatives), and compared pretreatment effectiveness of these solvents. Single ethanolamine was the best among ethanolamine-based solvents, indicating the unnecessity of deep eutectic solvent synthesis. Furthermore, structural characterization confirms that ethanolamine could effectively deconstruct Camellia oleifera shell with the highest delignification (76.46%) and sugar yields (83.73% for glucose and 66.87% for xylose) at 130 °C for 3 h. Additionally, correlation analysis suggests that alkalinity and proton dissociation capacity together determined the delignification capacity of ethanolamine. Our findings serve a potential solution to valorise the waste fruit shell lignocellulose resources.