Synergistic enhancement of U(VI) capture through targeted recognition and multifunctional group complexation using alanine-assisted ion-imprinted chitosan/hydrotalcite honeycomb foam

To address the shortcomings of existing chitosan/hydrotalcite adsorbent materials in terms of structural design and selectivity, this study successfully prepared an alanine-assisted ion-imprinted chitosan/Ca-Al hydrotalcite composite foam (ICAL) with a well-ordered honeycomb pore structure to enhance U(VI) adsorption performance. Among the ICAL materials prepared with different raw material ratios, the ICAL-2 foam exhibited a more ordered honeycomb structure and better homogeneous dispersion, and its ion memory effect facilitated rapid targeted capture of U(VI), thus demonstrating the optimal U(VI) adsorption performance. FTIR and XPS analysis results indicated that the N/O Lewis functional groups in ICAL-2 can effectively bind U(VI). The adsorption isotherm and adsorption kinetics could be described by the Langmuir model and pseudo-second-order model, respectively, indicating that monolayer chemisorption was dominant, with a saturated adsorption capacity of 333.9   mg/g at pH 5.0 and 298   K (the experimental capacity was 310.3   mg/g obtained at an initial U(VI) concentration of 100   mg/L). The adsorption of U(VI) by ICAL-2 was a spontaneous endothermic process, and it exhibited good adsorption selectivity for U(VI) in complex systems. The easily synthesized and recoverable ICAL-2 composite demonstrates promising potential for efficient treatment of uranium-contaminated wastewater through a targeted recognition-chemical complexation mechanism.