Structurally stable porous PEI/SA-XLS composite gel beads for reusable uranium recovery

Efficient adsorption and recoverable removal of uranium from aqueous media are crucial for resource utilization and environmental risk mitigation. However, conventional adsorbents often suffer from poor structural stability, limited reusability, and difficulties in deployment and recovery, which hinder practical applications. Herein, a robust macroporous ternary composite gel bead (PEI/SA-XLS) was fabricated from sodium alginate (SA), polyethyleneimine (PEI), and synthetic hectorite-type clay (laponite XLS) via synergistic polyelectrolyte complexation, supramolecular crosslinking, and freeze-drying. SA and PEI formed a 3D network through electrostatic interactions, while XLS nanosheets reinforced the framework through hydrogen bonding between surface silanol groups and amino/hydroxyl groups. Freeze-drying generated macropores (~100 μm), thereby significantly enhancing mass transfer and facilitating uranyl diffusion into the bead interior. Mechanistically, negatively charged XLS surfaces promoted electrostatic enrichment of UO 2 2+ , while silanol, amino, and carboxyl groups provided cooperative binding sites for efficient uranyl capture. The maximum adsorption capacity ( q m ) was ~2707 mg·g −1 (Langmuir). A removal efficiency of ~98% was achieved at 15.1 mg·L −1 ( V  = 100 mL), and ~ 93% efficiency was maintained after ten adsorption-desorption cycles. These results highlight that macroporous transport channels and mechanically robust pore walls play a dominant role in adsorption efficiency and cycling stability for macroscopic adsorbents.