(548d) 3D-Interconnected PVA-Citric Acid Porous Hydrogels Embedded with Potassium Copper Hexacyanoferrate Nanoparticles for Enhanced Removal of Radionuclide Cesium

A potassium copper hexacyanoferrate-embedded poly(vinyl alcohol)-citric acid hydrogel film (HPC) was prepared via a facile two-step method for the effective Cs⁺ removal. The synthetic procedure consisted of the simultaneous Cu dispersion and incorporation, followed by the diffusion of potassium hexacyanoferrate accelerated by acetone evaporation. The diffusion-derived KCuHCF formation in the preformed hydrogel facilitated not only the preservation of the 3D-interconnected hydrogel structure, but high dispersion of the nanostructured KCuHCF. Using acetone as a non-solvent, the reverse diffusion rate of the incorporated Cu in the hydrogel matrix was greatly reduced; hence a large amount of KCuHCF was loaded in the matrix.

The as-obtained HPC demonstrates the superior Cs⁺ adsorption capacity and selectivity with significantly fast removal kinetics. In the adsorption isotherm, the HPC showed a very high Cs⁺ uptake of 667 mg/g KCuHCF at the saturated concentration. Moreover, the uptake process was exceptionally fast with 99.5 % of Cs⁺ ions adsorbed within 30 min, and the overall Cs⁺ removal was 99.9 % from a dilute Cs⁺ solution (9.18 ppm). Even when tested in seawater, the HPC exhibited almost unaltered Cs⁺ removal efficiency above 99.5 %, and the high distribution coefficient K_d value of 7.7 x 10⁵ mL/g at an extremely low Cs⁺ concentration (0.67 ppm, V/m = 1000 ml/g), which highlighted the exceptional Cs⁺ affinity over all competing cations. In addition, this novel adsorbent represented the stable and high Cs⁺ removal efficiency of 99.9 % over a broad pH range from 2 to 10.

These enhanced removal properties are closely related to the synergistic effects of rich K⁺ contents in KCuHCF, well dispersion of the nanoparticles, and the fast swelling kinetics of the hydrogel matrix. Therefore, combined with the simple synthetic procedure and low production cost, the HPC is one of the most promising adsorbents for the rapid and selective removal of Cs⁺ from contaminated environments.