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Cesium-137 (137Cs) is a main product of the nuclear fission. The release of 137Cs can contaminate soil by deposition from the atmosphere. It is critical to develop a high-efficiency way to determinate 137Cs in the soil. To reach it, the sample pretreatment and 137Cs separation from sample matrix is significant. This work focused on the thermal stability of Cs(I) during soil dry ashing and acid solution evaporation. The separation performance of AMP-PAN resin for Cs(I) was investigated through batch and dynamic column experiments. The results reveal that Cs(I) does not loss during soil sample dry ashing (T < 600 °C) and acidic solution evaporation to dryness at 100 °C. The optimal condition for Cs(I) uptake by AMP-PAN resin was pH 0 − 4, and co-existing interference ions had a detrimental effect on Cs(I) adsorption. The adsorption capacity of AMP-PAN resin for Cs(I) was not significantly decreased after irradiation with different γ radiation doses. Cs(I) could be loaded on the column using 0.1 mol/L HNO3 and eluted with 5 mol/L NH4Cl solution with a high recovery of Cs than 90%. These findings shed fresh light on the separation of target element in the analysis of 137Cs in soil. [ABSTRACT FROM AUTHOR]

Developing novel adsorbents for efficient U(VI) adsorption from wastewater is of great significance in both nuclear energy development and environmental protection. Herein, a novel functional resin (AO67/MA33-resin) with large particle size (100–200 μm) was controllably synthesized and employed for U(VI) elimination. The AO67/MA33-resin overcomes the shortcoming of small particle size of traditional adsorbents and shows strong antacid and high-temperature resistance stability and reusability. Meanwhile, the AO67/MA33-resin also exhibits excellent U(VI) removal ability including wide pH adaptability, fast adsorption kinetic, and high adsorption capacity. The adsorption mechanism was determined to involve chelation between amidoxime carboxyl functional groups and uranyl ions. A further application for U(VI) removal from real uranium mine wastewater was evaluated by dynamic column experiments. The present work indicated that the AO67/MA33-resin would be a promising adsorbent material for uranium removal from wastewater. [ABSTRACT FROM AUTHOR]

Decontamination of the toxic selenium compound, selenite (Se(IV)) and selenate (Se(VI)), from wastewater is imperative for environmental protection. Efficient approaches to remove Se(IV) and Se(VI) are in urgent needs. In this work, an accessible adsorbent Fe–OOH–bent was prepared and applied for the removal of Se(IV) and Se(VI) from wastewater. The batch experimental results demonstrate that Fe–OOH–bent exhibits high adsorption capacities of 5.01 × 10−4 and 2.28 × 10−4 mol/g for Se(IV) and Se(VI) respectively, which are higher than most of the reported bentonite based materials, especially in the case of Se(VI). Moreover, the Fe–OOH–bent displayed superior selectivity towards Se(IV) and Se(VI) even in the presence of excess competitive anions (Cl−, HCO3−, NO3−, SO42− and PO43−) and HA with concentrations of 1000 times higher than Se(IV) and Se(VI). By evaluating the adsorption ratio of Se(IV) and Se(VI), the reusability of Fe–OOH–bent was great through five adsorption-desorption cycles. For practical application, the column experiments were performed with simulated wastewater samples. The breakthrough and eluting curves of Se(IV) and Se(VI) were investigated through the columns packed with Fe–OOH–bent, and the results show that Se(IV) and Se(VI) can be successfully separated and recovered using 0.1 mol/L Na2SO4 (pH = 9.0) and 0.1 mol/L Na3PO4 (pH = 9.0), respectively. Our work provides a new approach for fractional separation as well as the recovery of Se(IV) and Se(VI) from wastewater. [ABSTRACT FROM AUTHOR]

Because of high mobility, the immobilization of long-lived fission product 79Se (often existed as 79Se(IV) and 79Se(VI) anions) is a critical consideration in the repository of high-level radioactive waste. In this work, a Fe-OOH modified bentonite (Fe-OOH-bent) was synthesized as a potential filling material in the repository site for effective adsorption and present the migration of different species of 79Se. The adsorbent was characterized using FT-IR, XRD, XFS, zeta potential and BET to clarify its physical properties, compositions and structures. A good thermal and radiation stabilities of Fe-OOH-bent was confirmed by its stable uptake ratio for Se(IV) and Se(VI) compared to original samples. The batch experimental results show that Se(IV) and Se(VI) can be efficiently removed from aqueous by Fe-OOH-bent within 60 min with maximum adsorption capacities of 68.45 mg/g for Se(IV) and 40.47 mg/g for Se(VI) in the optimal conditions, indicating its high potential application in consideration of its simple synthesis process, low cost and high adsorption capacity in view of immobilization of 79Se. The surface species and variation of oxide state of Fe as well as Se(IV) and Se(VI) onto Fe-OOH-bent were investigated by XPS analysis. The values of relative area of Se(IV)–O and Se(VI)–O in XPS spectra followed the same tendency as their adsorption ratio with the variation of system pH, suggesting that the formation of complexes between selenium species and Fe-OOH-bent surface. [ABSTRACT FROM AUTHOR]

As a strategic resource, the safe management and recovery of uranium (U(Ⅵ)) is of great significance for environmental protection and resource recycling. To address it, the effective capture of U(Ⅵ) from wastewater is necessary but still challenging. In this work, an environmental-friendly adsorbent amidoxime and carboxyl functionalized microspheres (ACBs) were successfully prepared, characterized and evaluated for U(Ⅵ) adsorption. The ACBs exhibited outstanding adsorption abilities for U(Ⅵ) with high adsorption capacity, fast kinetics, good selectivity and excellent reusability. The U(Ⅵ) adsorption mechanism onto ACBs was synthetically investigated by various characterizations and DFT calculations, suggesting that the amidoxime and carboxyl groups coordinated with U(Ⅵ) by π and σ bonds. Further investigation in actual water samples and degradation experiments suggested that the ACBs can not only effectively remove U(Ⅵ) from wastewater, but also it can be completely degraded to achieve waste-free goals after the adsorption-desorption process. This work provides new insight into the significance of designing efficient and environmental-friendly adsorbent material for U(Ⅵ) removal from wastewater. [Display omitted] • An environmentally friendly adsorbent was prepared and used for U(VI) removal. • ACB shows powerful adsorption abilities for U(VI) under different conditions. • Adsorption mechanism was revealed as mixed coordination structures. • ACB can be degraded completely by bacteria to achieve no waste discharge. [ABSTRACT FROM AUTHOR]

[Display omitted] • HDPy-bent with high adsorption capacity and fast kinetic for 99TcO 4 − was synthesized. • HDPy-bent displayed superior selectivity towards 99TcO 4 −. • Adsorption mechanism of anion exchange and surface precipitation was confirmed by experiments and DFT simulations. • HDPy-bent was proved to be an excellent material for 99Tc decontamination from wastewater by successful column experiments. Technetium-99 (99Tc), as one of the important high-yield fission products, poses a significant threat to the environment and human health due to its radiotoxicity, long half-life, high solubility and mobility in the environment. Thus, removal of 99TcO 4 − from radioactive wastewater is considerably imminent for waste disposal and environment conservation. In this work, Hexadecylpyridinium Chloride Monohydrate modified bentonite (HDPy-bent) was synthesised and used as an adsorbent to remove 99TcO 4 −. The adsorption behaviours of ReO 4 − as an analogue for TcO 4 − were investigated as functions of contact time, solution pH, initial concentration, and competing anions using batch techniques. It is demonstrated that the HDPy-bent showed an excellent adsorption ability for ReO 4 − at the pH range of 2–11, fast adsorption kinetic (reaching equilibrium within 3 min at room temperature), and maintains desirable ReO 4 − adsorption in the presence of concomitant anions at an excessive concentration of 500 times (Cl−, HCO 3 −, NO 3 −, CO 3 2−, SO 4 2− and PO 4 3−). As for adsorption mechanism, we propose the anion exchange process at low concentration of Re(VII) and precipitation reaction at high concentration, while the driving force of the high ReO 4 − adsorption ability is the interaction between ReO 4 − anion and pyridinium ring of HDPy+, which is confirmed by density functional theory (DFT) simulations. Additionally, DFT studies also shed light on the adsorption structure of HDPy+/ReO 4 − and the origin of adsorption selectivity. Moreover, four adsorption-desorption cycles suggest that the HDPy-bent has good durability and reusability. Furthermore, ReO 4 − can be removed completely and recovered fractionally by using the chromatography column packed with HDPy-bent from simulated groundwater samples. The work presented herein demonstrates a low-cost adsorbent which can efficiently remove 99Tc from contaminated water. [ABSTRACT FROM AUTHOR]

[Display omitted] • U-PSresin was synthesized to use for separation and detection of U(VI). • U-PSresin shows good irradiation and thermal stability. • U-PSresin is demonstrated a highly sensitive detection efficiency of U(VI). • U-PSresin is proved to be used for continuous measurement of U(VI). It is extremely significant to monitor the radioactive uranium during the process of nuclear energy mining and disposal because of its high levels of chemical and radiological toxicity. In this work, a novel uranium plastic scintillator resin (U-PSresin) was successfully synthesized by suspension polymerization and used to rapidly enrich and determine uranium by Liquid Scintillation Counting (LSC). The U-PSresin shows excellent irradiation stability, extremely appropriate adsorption capacity of U(VI) (9.35 mg/g), which is convenient for the accurate measurement of LSC. Meanwhile, U-PSresin has a deviation of less than 5 % in adsorption and measurement repeatability and can be utilized to accurately measure more than 1 mg of natural uranium after enrichment. For different types of spiked water samples, the measurement deviation of U-PSresin is less than 15 %. This work demonstrates that U-PSresin can selectively enrich and quantitatively measure uranium in an aqueous environment, showcasing its significant potential in nuclear emergency scenarios and environmental monitoring. [ABSTRACT FROM AUTHOR]

• A highly efficient adsorbent was prepared and used for the treatment of uranium wastewater. • MXene/PAO hydrogel beads exhibit outstanding adsorption capacity under different conditions. • MXene/PAO hydrogel beads have excellent practicality coupling through columns. • Adsorption mechanism under F− conditions is the coordination of MXene and amidoxime to uranium complexes. The treatment of radioactive wastewater is crucial to ensure the safe and rapid development of nuclear energy. However, efficient disposal of uranium wastewater containing high concentrations of fluoride ions (F−) generated during uranium enrichment and conversion poses a formidable and pressing challenge. In this study, we successfully synthesized MXene/PAO hydrogel beads (MPH beads) by self-assembling two-dimensional Ti 3 C 2 T x MXene nanosheets with amidoxime through ionic cross-linking. MPH beads exhibited exceptional uranium adsorption capacity (625 mg/g), remarkable adsorption selectivity, and good reusability. Notably, MPH beads demonstrated a maximum uranium adsorption capacity of 400 mg/g in an aqueous solution containing 8000 ppm F−. Furthermore, MPH beads showed favorable F− resistance and were able to remove>95% of U(Ⅵ) even after being immersed in an extreme environment for 15 days. Additionally, MPH beads achieved a high U(Ⅵ) recovery of 98.2% from real environment water samples using dynamic column experiments, showcasing their excellent application performance. The efficient U(Ⅵ) adsorption and anti-fluoride effect were mainly attributed to the combined complexation between the C(NH 2) = N-OH, C-Ti-OH groups and U(Ⅵ), as demonstrated by experiments, characterization, and DFT calculations. Our study highlights the significant potential of MPH beads in the treatment of uranium from radioactive wastewater, especially wastewater with high concentrations of F−. [ABSTRACT FROM AUTHOR]