Fully upgrade lignocellulose into high-valued nanomaterials and chemicals through one-pot treatment by bio-acid tailored deep eutectic solvents

Achievement of efficient fractionation of lignocellulose and simultaneous valorization of corresponding components in one-pot biorefinery process remains as a great challenge. Here, we established an innovative approach employing bio-acid customized tertiary deep eutectic solvents (TDES) consisting of choline chloride and citric acid (maleic acid and lactic acid) alongside with presence of 1,4-butanediol, yielding three value-added products from biomass poplar: furfural, lignin nanospheres (LNS), and lignin-containing cellulose nanospheres (LCNS). The molecular interaction behaviors within lignin-lignin and lignin-deep eutectic solvents (DES) systems were predicted using density functional theory (DFT) and classical molecular dynamics (MD) methods. The TDES pretreated filtrate, abundant in hemicellulose (85 %), was successfully converted into furfural with a yield of 27 %. The resulting lignin underwent esterification with the bio-acid, in which the carboxyl group content increased by a remarkable 15-fold compared to cellulolytic enzyme lignin (CEL), providing a powerful driving force to obtain lignin nanospheres (<650 nm) through self-assembly process. The cellulose-rich residues with higher carboxyl content (1.25 mmol/g) were homogenized to fabricate lignin-containing nanocellulose spheres (LCNSs) with uniform size (200 nm) for the first time, acting as a promising right-handed chiral photonics with excellent photoluminescence properties. In summary, this work unveiled the potential of bio-acid tailored TDES as a sustainable medium for efficient fractionation of biomass components, achieving value-added nanomaterials and chemicals with substantial industrial downstream applicability.