Removal of surface-bound uranyl ions from solid substrates using a chitosan/gelatin composite hydrogel

A green chitosan/gelatin hydrogel was developed via a facile one-pot strategy without chemical crosslinkers. • The hydrogel achieved >90% uranyl removal on non-porous surfaces and 70.7% on porous cement. • Synergistic chemisorption (–NH₂/–COOH) and physical encapsulation (gelatin 3D network) enable high decontamination. In recent years, the expansion of nuclear energy infrastructure has intensified demand for efficient surface decontamination technologies. Hydrogels have emerged as promising candidates for surface decontamination owing to their high radionuclide removal efficiency and compatibility with heterogeneous substrate geometries. In this study, a natural polymer hydrogel based on chitosan and gelatin was developed, achieving high removal rates of uranyl contaminants from various substrates. The hydrogel exhibits advantages including a facile one-pot synthesis, biodegradability, and compliance with green chemistry principles. Glycerol was introduced as a plasticizer to enhance film flexibility and crack resistance, while titanium dioxide (TiO 2 ) nanoparticles were incorporated as rigid nanofillers to reinforce the mechanical strength of the gel network. Rheological characterization revealed that the precursor solution exhibits shear-thinning behavior, facilitating uniform application onto contaminated surfaces via brushing or spraying. High strength, high toughness, and high removal efficiencies can be achieved simultaneously by optimizing the concentration, temperature, and decontamination time during material design. Decontamination efficiencies reached 99.4% (stainless steel), 94.1% (glass), 98.8% (rubber), 96.0% (painted board), 91.3% (ceramic), and 70.7% (cement), substantially surpassing the performance of commercial decontaminants such as DeconGel. XPS confirmed that amino (-NH₂) and carboxyl (-COO⁻) groups from chitosan and gelatin, respectively, engage in inner-sphere coordination with UO 2 2 + , forming stable chelate complexes. Concurrently, the thermoreversible gelation of gelatin establishes a dense 3D network, which—upon solvent evaporation—physically entraps uranyl ions, thereby confirming a synergistic physicochemical decontamination mechanism. Owing to the abundance, low cost, and biodegradability of its constituents, along with the use of glycerol and TiO 2 as functional additives, this hydrogel system represents a green and sustainable alternative for surface decontamination in nuclear accident response and facility decommissioning scenarios. Download: Download high-res image (269KB) Download: Download full-size image