Synergizing mitigated spatial confinement and chemical stabilization of lignin facilitates full utilization of lignocellulose

Condensation, dark color and low extraction yield of lignin have hindered the full valorization of biomass during lignocellulosic fractionation. Herein, we introduce a novel biomass fractionation concept that addresses the issue of lignin's spatial confinement. Building upon this concept, we have devised an environmentally friendly and straightforward strategy. This approach involves a combination of selective carboxylation at the C_γ-OH position using citric acid and etherification at the C_α-OH position using butanol. The objective is to mitigate the spatial confinement of lignin and stabilize its active intermediates for lignin extraction. Consequently, up to 91.4 ± 0.2% lignin with a light color can be separated from the recalcitrant softwoods, as a UV blocker to improve the performance of sunscreen cream. The cellulosic residue can be enzymatically digested to glucose with a yield of 80%. The initiated biomass fractionation theory and strategy in this study provide a new concept for the isolation of lignin and full valorization of lignocellulose, promoting the development of a sustainable economy.