The De‐Shielding Effect of Water‐Cyclohexane Biphasic Cosolvent on Hemicellulose Fractionation of Biomass

ABSTRACT Solvent fractionation to separate cellulose, hemicellulose, and lignin from raw lignocellulosic biomass is important for its effective utilization. However, the solvent effect on the highly selective fractionation of hemicellulose in a biphasic cosolvent is unclear. In this research, molecular level simulations were conducted to study the performance of solvent on hemicellulose, cellulose, and lignin in water, cyclohexane, and water‐cyclohexane biphasic cosolvent. The results indicated that the three components gathered together in water, forming a “lignin‐hemicellulose‐cellulose‐hemicellulose‐lignin” five‐layer sandwich construction, which inhibited the contact between hemicellulose and water. In cyclohexane, a similar aggregation phenomenon was observed. Nevertheless, in water‐cyclohexane biphasic cosolvent, the cyclohexane, as the hydrophobic phase, provided additional van der Waals interaction to weaken the H‐bond and interaction between lignin and hemicellulose. The average number of H‐bonds and interaction were both decreased by about 60%, promoting the separation of lignin from hemicellulose, increasing the contact area between hemicellulose and water by about 50%, and enhancing the reaction of hemicellulose with water in the aqueous phase. This de‐shielding effect of water‐cyclohexane biphasic cosolvent might provide valuable insights for designing a greener hemicellulose fractionation solvent system.