Bioinspired fabrication of robust adsorbent hydrogels via hierarchical self-assembly of native lignocellulosic 2D...

Lignocellulose, the primary constituent of agricultural and forestry wastes, exhibits poor aqueous dispersibility and limited structural tunability due to its inherent 3D rod-like aggregate morphology, hindering its high-value utilization. This study proposes a tannic acid (TA)-mediated aqueous deconstruction-reassembly strategy, facilitating the transformation of unfractionated native lignocellulose from 3D bundled aggregates into 2D "brick-and-mortar" lamellar units, which synergistically form stable dispersions with MXene nanosheets. The strategy hinges on TA's polyphenol groups establishing synergistic dual hydrogen-bonding networks with lignocellulose surface hydroxyl groups and MXene surface oxygen-containing groups, thereby inducing interfacial coupling, promoting lamellar rearrangement, and effectively suppressing restacking and reaggregation. Multiscale characterization (SEM/TEM/AFM) confirms the ultrathin lamellar features (3 nm thickness) and homogeneous stacking of the 2D units. When integrated into sodium acrylate hydrogels, the 2D lamellae synergize with multifunctional groups to regulate pore architecture, forming hierarchical networks that enhance connectivity and shorten diffusion pathways. This boosts accessibility to active sites and adsorption kinetics, as evidenced by LTM-H's(lignocellulosic hydrogel) swelling ratio of 3762.61% and a monolayer saturation adsorption capacity of 47.10 mg·g^-1 for pollutant removal. Concurrently, the "brick-and-mortar" skeleton and TA-mediated dual H-bonding networks significantly reinforce mechanical properties, with LTM-H achieving a compressive stress of 10.29 MPa and retaining 98.2% of its initial strength after 10 compression cycles. This strategy enables scalable conversion of 3D aggregates to 2D functional units using cost-effective native lignocellulose (while preserving partial lignin/hemicellulose) from diverse agroforestry sources, offering a green and economically viable framework for 2D biomass utilization and sustainable adsorbent fabrication.