Safe and sustainable development of the nuclear industry has become the focus of attention, so it is important to manage byproducts of radioactive elements, such as uranium, which is inevitably discharged into water bodies. In this work, an adsorbent was fabricated by the in-site assembly of zeolitic imidazolate framework-67 (ZIF-67) on reduced graphene oxide (rGO) hydrogel. The adsorption property of the rGO/ZIF-67 aerogel toward U(VI) was studied via batch adsorption experiment. According to kinetic fitting tests, the adsorption property was in accord well with the pseudo-second-order model, revealing that the adsorption process was chemisorption; the results of the isothermal model conform to the Langmuir model, which exhibited an excellent adsorption capacity of 1888.55 mg/g. The thermodynamic parameter (ΔH° = 11.7 kJ/mol) obtained from the experimental data demonstrated that temperature rise is favorable for the adsorption. Based on the characterization of the material and results of the adsorption, the adsorption mechanism for U(VI) may be explained by surface complexation and electrostatic attraction. In general, all these results and characteristics of the adsorbent show that the rGO/ZIF-67 aerogel provides an alternative way to fabricate novel uranium adsorbent.

The effective adsorption of radioactive iodine is greatly desirable, but is still a significant challenge. In this manuscript, we report the synthesis of a bismuth-modified zinc aluminium layered double hydroxide (BiZnAl-LDH) via a co-precipitation method for the highly efficient absorption of iodine. Based on the robust chemical attraction between Bi and I₂, BiZnAl-LDH exhibited highly effective iodine capture. Furthermore, to evaluate BiZnAl-LDH as an effective sorbent, it was characterized via X-ray powder diffraction (XRD), scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), and Fourier-transform infrared spectroscopy (FITR). In addition, to determine the morphology and iodine adsorption properties of BiZnAl-LDH, several studies were conducted. Through experiments, its elemental composition and vibration before and after iodine adsorption were analyzed via EDS and X-ray photoelectron spectroscopy (XPS). During the capture process, I₂ is reduced to I⁻ by the intercalated Bi³⁺ via chemical adsorption, and the maximum adsorption capacity of BiZnAl-LDH for iodine reached up to 433 mg g⁻¹, which had a surface area, average pore diameter, and pore volume of 36.259 m² g⁻¹, 2.374 nm, and 0.128 m³ g⁻¹, respectively. Compared with several previous sorbents for iodine adsorption, BiZnAl-LDH exhibited an iodine adsorption of approximately two times that of the commercial Ag-exchange zeolite X, and furthermore BiZnAl-LDH is cost-effective. Thus, the substantial iodine capture by BiZnAl-LDH indicates that it is a capable sorbent for the effective elimination of radioactive iodine from reprocessing plant emissions.

Large-scale and rapid extraction of uranium from seawater are promising for overcoming the challenge of supply interruption to achieve sustainable nuclear energy production. However, existing uranium adsorbents are limited by bacterial contamination or low seawater flux for long-term operation. Inspired by the efficient nutrient absorption by animal small intestine folds, we have developed a continuous 3D intestine-fold-like hierarchical porous uranium adsorbent using a one-step cryo-polymerization technique. It shows 10 times higher uranium adsorption capacity than the same material without the intestine-fold-like structure. The continuous supermacro pores (10–100 μm) in the adsorbent provide rapid flow channels for seawater; the micropores (∼1 μm) in the pore walls provide a Schiff base and amidoxime sites for efficient uranium capture. Its functional and high-strength double network polymer chains show a compressive strength of 1.4–3.3 MPa. Within a period of seven days in natural seawater, the uranium adsorption rate was as high as 0.97 mg (g d)⁻¹. The presence of an antibacterial Schiff base allows the adsorbent to achieve a uranium adsorption amount of 10.45 ± 0.46 mg g⁻¹ after 30 days in natural seawater. Importantly, the cryo-polymerization technique proposed in this work simultaneously achieves the formation of hierarchical pores and is easily scalable for large-area preparation, providing a reliable adsorbent for seawater uranium extraction and contributing to the sustainable development of nuclear energy.

Calixarene-functionalized graphene oxide (GO) composites were synthesized via esterification and polymerization of calix[n]arenes (n = 4, 6, 8) onto graphene oxide surfaces for the first time. The GO composites were used to adsorb Nd ions from the aqueous phase due to their quite high BET surface areas. In this work, the GO composites (GO-C4, GO-C6, and GO-C8) showed high adsorption capacities (232.56, 219.78, and 311.53 mg g⁻¹, respectively) compared to GO (110.99 mg g⁻¹) during the removal process and excellent efficiency in removing a high concentration of neodymium ions (1150 mg L⁻¹) from water. The results indicate that the adsorption ability for Nd ions was in the order of GO-C8 > GO-C4 > GO-C6 > GO. The adsorption processes of GO-C4 and GO-C8 were completed within 185 min, whereas that of GO-C6 was achieved within 230 min. Furthermore, controlling the pH value of an aqueous solution in the range of 6, the GO composites exhibited the highest adsorption capacity toward Nd ions. For our process of removing Nd ions, the adsorption data of experiments mostly fit the pseudo-second-order model better than two other models. Four adsorption isotherm models were compared to study the details of the adsorption process, and the results indicated that the Freundlich model is the most suitable for describing the adsorption process of the GO composites. The adsorption mechanisms to remove Nd ions were the electrostatic attraction of Nd ions with hydroxyl functional groups and the complexation process of Nd ions with functional groups on the surface of the GO composite. Moreover, thermodynamic studies indicated that the adsorption behavior of the GO composites towards Nd ions was an endothermic and spontaneous natural process. In general, GO composites could potentially be applied to metal ion removal.