Swelling-programmed hemicellulose/chitosan cryogels with tunable porous transport for rapid selective adsorption

The sustainable porous materials are highly desirable for achieving rapid and selective ionic separation in water purification, yet the relationship between swelling-induced pore evolution and transport behavior remains insufficiently understood. Here, a swelling-mediated porous transport strategy is reported for biomass-derived cryogels. By regulating the swelling state of hydrogel precursors before freeze-drying, dialdehyde hemicellulose/chitosan cryogels (DHC) with programmable interconnected pores were constructed. The optimized cryogels showed ultrafast water uptake (<1 s), reversible compressibility under 80% strain, and stable porous transport during repeated operation. Swelling-programmed pore architectures accelerated dye diffusion and adsorption kinetics, enabling DHC-240 to reach a maximum Orange G (OG) adsorption capacity of 785.64 mg/g and rapid separation within 1 min. In mixed dye systems, DHC-240 showed high ionic selectivity, with selectivity coefficients up to 3319. Molecular simulation revealed charge-dependent adsorption. Anionic OG and fluorescein sodium (FS) maintained stable binding distances of 5.64 and 7.13 Å, whereas cationic dyes showed unstable, energetically unfavorable interactions. Energy decomposition highlighted docking interaction energy as the dominant contribution (-33.8 kcal/mol), and free-energy analysis confirmed favorable OG binding (-2.1 kcal/mol) versus unfavorable methylene blue binding (+1.6 kcal/mol). This work establishes swelling-regulated pore programming for transport-controlled molecular separation.