Yuezhou Wei

Cesium and strontium (Cs/Sr) are key radionuclides in radioactive wastewater. Dynamic fixed-bed adsorption is a practical approach for Cs/Sr removal, but engineering-scale design remains challenging because laboratory-derived breakthrough models have rarely been validated against independent pilot-scale data. Here, a mechanistic framework was developed and independently validated for a layered column containing silica-supported ammonium molybdophosphate (AMP/SiO₂) and silica-supported potassium hexatitanate (K₂Ti₆O₁₃/SiO₂) as Cs- and Sr-selective beds. An axial-dispersion model with material-specific equilibrium relations and an effective liquid-concentration driving-force coefficient was calibrated solely against laboratory breakthrough curves. The resulting parameters were transferred without refitting to a pilot-scale column operated with a seawater-like feed, representing a 1500-fold increase in adsorbent mass. Laboratory calculations yielded R² values of 0.997 for Cs and 0.998 for Sr. The pilot calculation reproduced the Sr curve with R² = 0.974 and RMSE = 0.068; the predicted 5% breakthrough volume (V₅) differed from experiment by 3.6%. Propagated V₅ uncertainty limits were ≤9.3% for Cs and Sr. Cs remained below 5% breakthrough through 44.2 L. Sensitivity analysis identified equilibrium capacity and feed concentration as the principal controls on breakthrough bed volumes; geometry and transport affected bed utilization and front width. These results support model-based scale-up under the tested conditions.

Despite its critical role in disease diagnosis as a radiopharmaceutical, Fluorine-18 generates medical wastewater that necessitates efficient treatment, for which membrane adsorption stands out as a potent method, albeit one that demands high-performance membranes with exceptional permeability and adsorption capacity. This study presents a novel cerium-loaded amyloid fibril hybrid membrane designed for efficient removal of fluorine-18 from such wastewater. The membrane is fabricated through a facile process involving oxidation–precipitation of cerium species onto amyloid fibrils, followed by vacuum filtration, with further compositional tuning via incorporation of porous silica or activated carbon dopants. The resulting membrane retains the characteristic amyloid fibril structure and exhibits high water permeability with a flux of up to 803.3 L/(m²·h·bar), superior to most of the other membrane materials. It effectively removes fluoride ions (F⁻) from both low and high-concentration solutions, achieving a removal efficiency of up to 99% and a maximum adsorption capacity of 580 mg/g, outperforming many existing membrane materials. The hybrid membrane also demonstrates notable resistance to ionic interference, enabling selective F⁻ adsorption from solutions containing high concentrations of Cl⁻, NO₃⁻ and SO₄²⁻, with a distribution coefficient (Kd) as high as 4.1 × 10⁴ mL/g; furthermore, it maintains a fluoride removal rate above 51% after ten consecutive adsorption cycles. The membrane retains 51% of its initial fluoride removal efficiency after 10 cycles, indicating potential for repeated use, although further optimization or regeneration strategies would be required to fully restore performance. Mechanistic investigations reveal that F⁻ adsorption occurs mainly through ion exchange with hydroxyl groups on CeO₂. This work introduces a promising novel material with significant potential for the efficient treatment of medical radioactive wastewater containing fluorine-18.

The sustainable development of nuclear energy requires a secure long-term uranium supply. Seawater uranium extraction offers a nearly inexhaustible resource; however, its commercialization is limited due to high costs. To improve economic viability, this study proposes a synergistic strategy for simultaneously recovering uranium and vanadium using amidoxime-based adsorbents, with vanadium as a valuable co-product. Herein, a porous silica-supported poly(amidoxime) adsorbent was synthesized and characterized. The material possesses a well-developed porous structure with a specific surface area of 49.8 m² g⁻¹. Spectroscopic analyses confirmed the successful grafting of amidoxime groups onto the silica framework, whereas X-ray photoelectron spectroscopy revealed that uranium adsorption occurs via coordination with nitrogen and oxygen donor atoms. Batch experiments demonstrated rapid adsorption equilibrium within 2 h and a maximum Langmuir uranium capacity of 48.5 mg g⁻¹ at 45 °C. The adsorbent exhibited high selectivity toward uranium over vanadium and competing ions at near-neutral pH. Dynamic column experiments demonstrated efficient stepwise separation using 0.1 mol L⁻¹ HNO₃ for uranium and a Na₂CO₃–H₂O₂ system for vanadium, even in simulated seawater containing high concentrations of competing ions. Under the controlled model conditions employed, this study demonstrates a promising adsorbent and a feasible co-recovery strategy that may contribute to enhancing the economic feasibility of seawater uranium extraction, warranting further validation in natural seawater.

Radioactive Ba²⁺ poses significant risks to nuclear safety and environmental protection, yet its efficient removal from nuclear wastewater remains a considerable challenge. Herein, Mg-Al layered double hydroxides (LDHs) were synthesized via a co-precipitation method and systematically optimized by tuning the Mg/Al molar ratio and calcination temperature. The optimal material, obtained by calcining Mg-Al LDH with a Mg/Al ratio of 4:1 at 450 °C (denoted as HT-450), exhibited a high apparent Ba²⁺ uptake capacity of 416 mg g⁻¹ and reached equilibrium within 15 min. Structural and spectroscopic analyses indicate that Ba²⁺ immobilization is more appropriately described as a reconstruction-coupled, interfacially mediated mineralization process, in which insoluble BaCO₃ forms in close association with the reconstructed HT-450 surface rather than through simple reversible adsorption or ion exchange. HT-450 also exhibited stable performance over a wide pH range of 3–7, high selectivity toward Ba²⁺ in the presence of competing mono-, di-, and trivalent cations, and excellent radiation tolerance, retaining approximately 95% of its initial uptake capacity after exposure to 200 kGy high-energy electron irradiation. These results demonstrate that HT-450 is a promising candidate for the rapid and stable immobilization of Ba²⁺ from Ba-containing radioactive wastewater.

Although ²¹² Pb and ²¹² Bi have significant applications in targeted α‐nuclide therapy for malignant tumors, their use is limited by the scarcity of ²¹² Pb/ ²¹² Bi resources. To address this bottleneck problem, an advanced strategy for selectively extracting ²¹² Pb and ²¹² Bi from the decay chain of ²³² Th is first proposed by using an efficient porous silica‐supported anion exchanger in bromide medium. The selective adsorption mechanisms of the resin for Pb(II) and Bi(III) in bromide medium are first clarified through spectroscopic analyses and theoretical calculations. Using the novel method and exchanger, 2.07 MBq of ²¹² Pb is successfully separated from ²³² Th and its daughters, with a record‐breaking chemical yield of 88.2% and an estimated radionuclide purity of over 99.9%. Mechanism analysis suggests that Pb(II) and Bi(III) can form anionic complexes in the HBr medium, with [PbBr ³ ] ⁻ and [BiBr ₅ ] ²⁻ being the main species captured; while Th(IV), Ac(III) and Ra(II) mainly exist as cationic forms and thus can't be fixed. To date, this represents the first report of successfully extracting ²¹² Pb/ ²¹² Bi from ²³² Th and its daughters using anion exchanger in bromide medium, as well as the mechanism illustrations, which enables the supply of ²¹² Pb/ ²¹² Bi directly from the abundant natural thorium resource to be possible.

Although 212Pb and 212Bi have significant applications in targeted α-nuclide therapy for malignant tumors, their use is limited by the scarcity of 212Pb/212Bi resources. To address this bottleneck problem, we first proposed an advanced method for selectively extracting 212Pb and 212Bi from the decay chain of 232Th using an efficient porous silica-supported anion exchanger. The selective adsorption mechanisms of the resin for Pb(II) and Bi(III) were clarified through spectroscopic analyses and theoretical calculations. Using the new method, we successfully separated 2.07 MBq of 212Pb from 2 kg of Th(NO3)4·xH2O, achieving a record-breaking chemical yield of 88.2% and an estimated radionuclide purity of over 99.9%. Mechanistic analysis suggested that Pb(II) and Bi(III) could form anionic complexes in the HBr medium, with [PbBr3]− and [BiBr5]2− being the main species captured; while Th(IV), Ac(III) and Ra(II) mainly existed as cationic forms and thus could not be fixed. Unlike traditional extraction methods for 212Pb/212Bi, this method is not constrained by the supply of scarce 224Ra or 228Th, giving this method significant theoretical and practical value. To date, this represents the first report of directly extracting MBq-level 212Pb from 232Th using anion exchanger or non-crown-ether materials.

The presence of impurities Fe and trace radioactive U in rare earth elements (REEs) may lead to a significant decline in the performance of high-purity rare earth products. For deep removal from REEs in a green and efficient way, an amine-functionalized silica-based adsorbent, TNDA/SiO₂-P, was prepared by a simple vacuum impregnation method, which had a high organic loading rate of 31.2 wt.%. The experimental results showed that it exhibited good adsorption selectivity for uranium and iron, with separation factors SF_U/REE = 20147 and SF_Fe/REE = 88128 in 5 M HCl. The adsorption kinetics was fast, with equilibrium obtained in 120 min. The 0.1 M HCl can desorb U and Fe efficiently. The deep removal of U and Fe from REEs including Sc can be achieved through chromatographic column separation with high enrichment. FT-IR, XPS and DFT calculations mutually confirmed that protonated TNDA/SiO₂-P exhibited a selective mechanism for uranium and iron in complex anion species in the hydrochloric acid system. This demonstrates its potential for efficiently removing trace impurities U and Fe from REEs.

This work develops a novel phosphate-functionalized extraction resin (HEHEHP + Cyanex272)/SiO₂-P via the vacuum impregnation method for efficient separation of light rare earth element impurities from lanthanum (La³⁺) in nitric medium through synergistic extraction. Batch experiments have demonstrated superior adsorption selectivity toward impurity ions over La³⁺ in a pH 4 nitric acid solution. Column studies confirmed exceptional performance under ambient conditions, achieving a lanthanum treatment capacity of 120.6 mg/g and over 98% impurity removal, which surpasses most reported values. Notably, this purification process enables direct production of purified La³⁺ solutions through a single-column system without desorption, significantly enhancing efficiency and reducing costs. Mechanistic insights revealed combined ion exchange and coordination interactions between metal ions and P-OH/P=O groups, corroborated by advanced characterization and density functional theory calculations. These findings indicate a higher binding affinity of light rare earth compared with La³⁺. This strategy provides a scalable approach for ultra-high-purity lanthanum compound production in advanced optical and electronic applications.

Bis(2-ethylhexyl) phosphate (P204) is widely used in extraction processes in the nuclear and rare earth industries. However, its high solubility in water results in high levels of total organic carbon and phosphorus in aqueous environments, and may also lead to radioactive contamination when it is used to combine with radionuclides. In this paper, we characterized a coconut shell activated carbon (CSAC) and a coal-based activated carbon (CBAC) for the adsorption of P204 and then evaluated their adsorption performance through batch and column experiments. The results found that, except for the main carbon matrix, CSAC and CBAC carried rich oxygen-containing functional groups and a small amount of inorganic substances. Both adsorbents had porous structures with pore diameters less than 4 nm. CSAC and CBAC showed good removal performance for P204 under low pH conditions, with removal efficiencies significantly higher than those of commonly used adsorption resins (XAD-4 and IRA900). The adsorption kinetics of P204 conformed to the pseudo-second-order kinetic model, and the adsorption isotherms conformed to the Langmuir model, indicating a monolayer chemical reaction mechanism. Both adsorbents exhibited strong anti-interference capabilities; their adsorption performance for P204 did not change greatly with the ambient temperature or the concentrations of common interfering ions. Column experiments demonstrated that CSAC could effectively fix dissolved P204 with a removal efficiency exceeding 90%. The fixed P204 could be desorbed with acetone. The findings provide an effective method for the recovery of P204 and the regeneration of spent activated carbon, which shows promise for practical applications in the future.