A clean deconstruction of steam-exploded corn straw into high purity cellulose nanosheets and well-defined lignin nanotubes

Abstract

The efficient and structure-protective isolation of the main components of lignocellulosic biomass remains challenging for value-added utilization. In this study, we used corn straw waste, a vast yet underexplored biomass from agricultural residues, as the raw material to extract high-purity cellulose nanosheets and recycle the lignin components as well-defined lignin nanotubes (LNTs) in a tandem process. The process consisted of a feasible dilute alkali-assisted wet ball milling treatment of steam-exploded corn straw into high-purity cellulose nanosheets and a lignin solution, which was further transferred into LNTs by a molecular assembly method. Purity, morphology, chemical structure, and thermal behavior of high-purity cellulose nanosheets and LNTs were examined. The 98.9 wt% purity of the high-purity cellulose nanosheets was achieved with a crystallinity of 36.9 %, providing a solid foundation for further chemical modification. The LNTs exhibited remarkable antioxidant activity, opening new avenues for the development of lignin-based functional materials and fundamental research.