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A convenient method was developed for rapid determination of Pu in environmental water samples. The analytical procedure involves preconcentration of Pu using TEVA extraction chromatography implemented in a vacuum box setup, and measurement of 239 +240 Pu by low background liquid scintillation counter (LSC). Chromatographic behaviors of plutonium, uranium, thorium, and americium were investigated, and the size of chromatographic column, concentration and flow rate of uploaded medium/washing liquid, and composition of eluent of Pu(Cl − ) 6 2 − -on TEVA column were explored. The results show that all the above factors affect the adsorption and desorption of Pu(Cl − ) 6 2 − -on TEVA column. Decontamination factors of more than 1 × 10 4 for uranium and 1 × 10 3 for thorium and americium were achieved. Chemical yields of plutonium in the overall procedure range from 70% to 98% and a detection limit of 6 × 10 − 3 Bq L − 1 in 60 min counting time for 5 L of water samples were obtained. The method has been successfully applied for rapid and effective determination of low level Pu in water samples. The analytical results show a good agreement with the values obtained using the conventional method. Compared with the conventional analytical procedure, the time consumption and labor intensiveness of the new procedure were greatly reduced and the analysis throughput was greatly increased with low analysis cost. The method is applicable to routine and emergency radiometric assays. [ABSTRACT FROM AUTHOR]

Se(IV) sorption on purified Na-kaolinite was investigated under ambient temperature as functions of contact time, pH, ionic strength and Se(IV) concentration using batch techniques. The rate of sorption is relatively rapid and sorption kinetics of Se(IV) can be successfully described by the pseudo-second-order model. The amount of Se(IV) sorbed was moderately dependent on the solution pH but insensitive to ionic strengths. The sorption/desorption isotherms of Se(IV) show that the sorption process is reversible. A double layer model was set up and used to quantitatively interpret the experimental data. Three surface complexes (≡Al)SeO, ≡ AlSeO and ≡AlOHSeO were proposed which satisfactorily fit our data. [ABSTRACT FROM AUTHOR]

Bentonite has been studied extensively because of its strong sorption and complexation ability. In this work, the sorption of Se(IV) on purified GMZ bentonite was investigated under ambient temperature as functions of contact time, pH, Se(IV) concentration and co-existing ion Eu(III) using batch techniques. Sorption kinetics of Se(IV) was successfully described by the pseudo-second-order rate equation. The sorption amount of Se(IV) was strongly dependent on the solution pH, and a positive effect was observed on Se(IV) and Eu(III) co-sorption when these two elements existed in the same system under high surface coverage of sorbent. Double layer model was set up and used to quantitatively interpret the sorption experimental data collected in binary and ternary sorption systems. From the experimental results, one can conclude that GMZ bentonite may have good potentialities for immobilizing selenium in nuclear wastes. [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]

The concentration of 99Tc was determined in archived time series seaweed samples collected at Klint (Denmark). The results demonstrate a significantly seasonal variation of 99Tc concentrations in Fucus vesiculosus with maximum values in winter and minimum values in summer. The mechanism driving this seasonal cycle was explored. With the measured 99Tc concentration in seawater collected in the same location and date as for seaweed, the concentration factor of F. vesiculosus to 99Tc was investigated. Constant value of concentration factors of 99Tc independence of sampling date, with an average value of (1.9 ± 0.5) × 105 L/kg, were obtained. This indicates that F. vesiculosus can be used as a reliable bio-indicator to monitor 99Tc concentration in seawater. [ABSTRACT FROM AUTHOR]

Metal ions sorption can be significantly affected by the presence of other sorbates, especially of complexing ligands. In this study, the effect of Se(IV) on Eu(III) sorption onto TiO at different pH and Eu(III) concentration was investigated. Se(IV) was found to enhance Eu(III) sorption as a function of Se(IV) concentration. Constant capacitance model was successfully used to interpret the sorption experimental data. The solubility product of Eu(SeO) at ambient temperature was investigated to highlight the sorption mechanism of ternary sorption system. The p K value of Eu(SeO) was found to be 31.51 ± 0.95. [ABSTRACT FROM AUTHOR]

Abstract: Due to the lack of a stable technetium isotope, and the high mobility and long half-life, 99Tc is considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. 99Tc is also an important tracer for oceanographic research due to the high technetium solubility in seawater as TcO4 −. A number of analytical methods, using chemical separation combined with radiometric and mass spectrometric measurement techniques, have been developed over the past decades for determination of 99Tc in different environmental samples. This article summarizes and compares recently reported chemical separation procedures and measurement methods for determination of 99Tc. Due to the extremely low concentration of 99Tc in environmental samples, the sample preparation, pre-concentration, chemical separation and purification for removal of the interferences for detection of 99Tc are the most important issues governing the accurate determination of 99Tc. These aspects are discussed in detail in this article. Meanwhile, the different measurement techniques for 99Tc are also compared with respect to advantages and drawbacks. Novel automated analytical methods for rapid determination of 99Tc using solid extraction or ion exchange chromatography for separation of 99Tc, employing flow injection or sequential injection approaches are also discussed. [Copyright &y& Elsevier]

• An efficient and economic HDPy-bent material was synthesized and applied for removing 99Tc from contaminated water. 99Tc is one of the critical fission products in the treatment of wastewater and the nuclear waste repository due to its long half-life (t 1/2 = 2.13 × 105 y), high fission yield (~6%), and high mobility in the environment. The development of highly-efficient, low-cost and easily available materials that can rapidly and selectively remove 99Tc is of great significance, but remains a challenge. In this work, bentonite-based materials (HDPy-bent) were obtained through modifying bentonite with hexadecylpyridinium (HDPy) and applied for the remove of TcO 4 − as well as its surrogate ReO 4 −. The structure of HDPy-bent (e.g., the values of d 001) was evaluated and the maximum loading amount of HDPy on bentonite was found to be 200% CEC. The loaded HDPy+ might replace exchangeable cations in the inter-layer space of bentonite. Batch experiment results show that HDPy-bent could quantitatively remove TcO 4 − from aqueous solution within 3 min. The distribution coefficient (K d) of TcO 4 − in this material is up to 2.1 × 105 mL/g, which is significantly higher than most of the previously tested inorganic adsorbent materials. More importantly, HDPy-bent can selectively remove TcO 4 − in the presence of large excess (80,000 times) of competitive anions (NO 3 –, SO 4 2−, CO 3 2−, PO 4 3− and Cl−). This work demonstrates that the HDPy-bentonite is a low cost, and effective adsorbent for removing 99Tc from contaminated water. [ABSTRACT FROM AUTHOR]

• Graphene oxide quantum dots stabilized Pickering emulsion (GQPE) was prepared. • GQPE demonstrated control release in vitro and is an antigen reservoir in vivo. • GQPE was a facile, effective, and safe adjuvant in enhancing immunity. Graphene oxide quantum dots (GOQDs), which are graphene-based nanoparticles, are potential surfactant substitutes for stabilizing Pickering emulsions, due to their high surface area, biodegradability, and reasonable biocompatibility. In the present study, GOQDs stabilized Pickering emulsion (GQPE) was prepared by simple sonication and then used as an adjuvant to enhance immune responses to the Chlamydia trachomatis Pgp3 recombinant vaccine. Immunization of mice showed that GQPE robustly activates adaptive immunity by efficiently stimulating IgG, sIgA, IFN-γ, IL-4, and TNF-α production. Controlled release repository of antigens both in vivo and in vitro prolonged the immune response. In addition, GQPE enhanced dendritic cell recruitment at the injection site, ensuring rapid and efficient innate immunity. Safety assessment revealed that GQPE does not cause liver, kidney, and myocardial damage in mice, suggesting its favorable biocompatibility. This study provides evidence for the use of GOPE as a facile, effective, and safe strategy to enhance the immune response to Pgp3 recombinant vaccines. [ABSTRACT FROM AUTHOR]

The effect of pH, contact time, temperature, ionic strength and initial U(VI) concentration on U(VI) sorption onto K-feldspar was investigated using batch techniques. The sorption kinetics was evaluated and the activation energy was obtained based on the rate constants at different temperature. Graphical correlations of sorption isotherm models have been evaluated and applied for U(VI) uptake by K-feldspar. Various thermodynamic parameters, such as, Gibb's free energy, entropy and enthalpy of the on-going sorption process have been calculated and the possible sorption mechanism of U(VI) was deduced. The results are expected to help better understand the migration of uranium in the host materials of granite. [ABSTRACT FROM AUTHOR]

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]

Accurate determination of Se in tea is critical for the quality control and safety of Se supplements. In this paper, we developed a rapid and automatic method for the determination of Se in tea samples using mixed acid (VHNO3:VHClO4 = 4:1) digestion followed by ion exchange chromatographic separation coupled to high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) measurement. The radionuclide 75Se was used as a tracer to monitor the loss of Se during entire separation procedure. The application of an automatic separation system speeded up the separation procedure and shortened the entire analytical time to less than 3 h. High performance liquid chromatography measurement of the sample solution after acid digestion shows the species of Se in the digests was Se(VI). 20 mL of HNO3 (> 5 mol L−1) can effectively elute Se from the column, and ~ 95% of Se can be eluted using 20 mL of 6 mol L−1 HNO3. The decontamination factors of more than 1 × 106 were achieved for the major interfering elements (Ca, Zn and Cu) by forming polyatomic ions for mass spectrometric measurement of 82Se by HR-ICP-MS. Meanwhile most of Br can be also removed and the key interference of 81Br1H+ was significantly suppressed in the HR-ICP-MS measurement of 82Se. The average chemical yield of 75Se was 93.2 ± 0.5%, which fall within 95% confidence interval. The developed method was validated through the analysis of certified reference materials, the measured values are in a good agreement with certified values, confirming the analytical method is reliable and accurate. The method established in this work has been successfully applied for the analysis of some commercially available tea leave samples. [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]

[Display omitted] • This material is capable of withstanding highly acidic (3–8 M HNO 3), highly radioactive (∼200 kGy), and highly heated (∼200 °C) conditions. • It has good stability, being able to withstand prolonged exposure to high acid without any impact on its efficacy. • The material has great selectivity, and even when there are hundreds or thousands of times more interfering ions, it still has a particular selectivity to Eu(III). • This material is cost-effective, its synthesis is uncomplicated, the raw materials are readily available, and it can be reused - these are all advantages. Americium (Am), a radioactive element, is highly valued for its commercial uses. Its source is primarily derived from high-acid, high-radiation, and high-temperature high-level radioactive waste liquids, requiring materials that are capable of enduring the most intense conditions for its capture. For this challenging environment, we successfully created a composite material TODGA@SiO 2 that is capable of effectively separating Am3+. An exhaustive evaluation of the material was undertaken, focusing on essential parameters and the column behavior of the material to ascertain its suitability for engineering applications. The composite is highly resistant to acid (>3 M HNO 3), can withstand temperatures up to 200 °C, and is radiation resistant up to 200 kGy, making it a great choice. Highlighting its suitability for radioactive waste, the adsorbent exhibited outstanding stability even after being soaked in 3 M HNO 3 for 11 days. In terms of performance, this material had a rapid kinetics (1 min, >95 %), a considerable adsorption capacity (K d value close to 3 × 105 mL/g), and a high selectivity for Am3+. From a cost and environmental protection perspective, the adsorbent can be regenerated and reused at least five times, and the extractant structure adheres to the CHON (Carbon, Hydrogen, Oxygen, and Nitrogen) principle, so orderly disposal is simple. At the same time, the high column efficiency, with a recovery rate of Am3+ of more than 94 %, makes its industrial application highly practical. In comparison to existing adsorbents, the material reported in this work has shown greater efficacy, making it a suitable inorganic composite for Am3+ extraction from radioactive liquid waste. [ABSTRACT FROM AUTHOR]

Removal of uranium from radioactive wastewater with TPEAC. [Display omitted] • A phosphine-oxime modified adsorbent (TPEAC) was successfully prepared. • TPEAC exhibited exceptional selectivity and efficiency for adsorption of uranium. • TPEAC displayed a high recovery of 99.6% using real uranium mining wastewater. • Adsorption mechanism was elucidated through experiments and characterization. Efficient removal of uranium from radioactive wastewater is paramount for the sustainable development of nuclear energy. However, the exploitation of superior adsorbents with practical applications remains a challenge. In this work, we engineered and synthesized an adsorbent (TPEAC) enriched with phosphine-oxime, featuring a matrix composed of hydrophilic modified amidoxime functional groups. TPEAC exhibited exceptional selectivity (Multiple ion coexistence R% > 99 %) and efficiency in uranium adsorption, with a higher adsorption rate (reach equilibrium around 400 mins) and capacity (243.9 mg/g) than raw-amidoxime (133.3 mg/g) and modified-amidoxime (175.4 mg/g) materials. Moreover, it maintained robust stability and reusability even after six adsorption–desorption cycles, with removal ratio still above 95 %. In-depth mechanistic investigations through DFT and XPS elucidated that P-O (P=O) groups exhibited a stronger affinity for U(VI) compared to other functional groups, and the adsorption of TPEAC towards U(VI) primarily due to the synergistic interaction among P-O (P=O) groups, C(NH 2) = N-OH, and carboxyl groups, which significantly facilitated the effective removal of U(VI). Most prominently, TPEAC performed considerable potential in processing actual uranium mine wastewater, with its dynamic column device achieving a U(VI) recovery up to 99.6 %. This work not only furnishes an efficacious and economical solution for uranium wastewater treatment but also provides new approaches for scalable application uranium materials. [ABSTRACT FROM AUTHOR]

Monitoring of radionuclide concentration in natural samples is important for assessing environmental safety. The low concentration of long-lived radionuclides require concentration from large volumes of natural water samples. This paper presents a method for sequential separation and simultaneous determination of radioisotopes of U, Pu, Am and Tc in water samples. Actinides and technetium were pre-concentrated by coprecipitation with iron hydroxides from the aqueous sample. Separation of actinides and Tc was achieved by extraction chromatography. The developed method allows separation of actinide and technetium from 100 L water with chemical yields between 40 and 70%. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel extractant resin DtBuCH18C6@CG-71 was successfully prepared with simple and low-cost method. • DtBuCH18C6@CG-71 exhibited remarkable separation ability of Sr(II) even in high concentration HNO 3 (3–12 mol/L). • DtBuCH18C6@CG-71 possessed great acid, irradiation and thermal resistance stability. • DtBuCH18C6@CG-71 can adeptly sequesters and recovers Sr(II) from wastewater via an automated separation system. Effective removal of radioactive 90Sr is crucial for both management of spent nuclear fuel and recovery of radioactive strontium resources, while it's still a great challenge due to the presence of high acid levels and intense radiation. Herein, a novel porous resin (DtBuCH18C6@CG-71) were synthesized by introducing 4′,4″(5″)-di- tert -butyldicyclohexano-18-crown-6 onto CG-71 resin using vacuum impregnation. The DtBuCH18C6@CG-71 resin maintains superior adsorption abilities in extreme conditions, including high acid resistance (3–12 mol/L HNO 3), substantial γ-irradiation (200 kGy 60Co), and elevated temperatures (50–100 ℃). Impressively, even when exposed to a high concentration of matrix ions (59 elemental ions), the Sr(II) adsorption ratio onto DtBuCH18C6@CG-71 resin remains near 100 % even in highly acidic condition, which performance outpaces most of commercial resins. Dynamic column tests using an automated separation system further confirmed the superior ability of DtBuCH18C6@CG-71 in term of extracting Sr(II) from wastewater. Given its impressive features, cost-effectiveness, and scalability, DtBuCH18C6@CG-71 resin holds promising potential for 90Sr disposal in nuclear wastewater. [ABSTRACT FROM AUTHOR]

Transuranium elements such as Np, Pu and Am, are considered to be the most important radioactive elements in view of their biological toxicity and environmental impact. Concentrations of 237Np, Pu isotopes and 241Am in two sediment cores collected from Peter the Great Bay of Japan Sea were determined using radiochemical separation combined with inductively coupled plasma mass spectrometry (ICP-MS) measurement. The 239,240Pu and 241Am concentrations in all sediment samples range from 0.01 Bq/kg to 2.02 Bq/kg and from 0.01 Bq/kg to 1.11 Bq/kg, respectively, which are comparable to reported values in the investigated area. The average atomic ratios of 240Pu/239Pu (0.20 ± 0.02 and 0.21 ± 0.01) and 241Am/239+240Pu activity ratios (3.32 ± 2.76 and 0.45 ± 0.17) in the two sediment cores indicated that the sources of Pu and Am in this area are global fallout and the Pacific Proving Grounds through the movement of prevailing ocean currents, and no measurable release of Np, Pu and Am from the local K-431 nuclear submarine incident was observed. The extremely low 237Np/239Pu atomic ratios ((2.0–2.5) × 10−4) in this area are mainly attributed to the discrepancy of their different chemical behaviors in the ocean due to the relatively higher solubility of 237Np compared to particle active plutonium isotopes. It was estimated using two end members model that 23% ± 6% of transuranium radionuclides originated from the Pacific Proving Grounds tests, and the rest (ca. 77%) from global fallout. [Display omitted] • Distribution of transuranium radionuclides in the sediment cores were investigated. • The contribution of transuranium from PPG was estimated to be 23 ± 6 %. • No measurable release of transuranium from K-431 incident was observed. • 237Np/239Pu atomic ratio might be unsuitable for the source identification. [ABSTRACT FROM AUTHOR]

99Tc primarily exists high mobility in the natural aqueous environment due to its extremely high solubility and non-complexing features, which can easily cause radioactive pollution. We herein report a general strategy for constructing a novel resin (SiPAN-PEI) with multiple positive charges nitrogen, exhibiting ultrafast adsorption kinetics (< 3 min), superior adsorption capacities (463.96 mg g−1), and excellent selectivity in the presence of excess competitive anions, which exceed those of most commercial resins. Moreover, based on impressive structure stability in extreme conditions, SiPAN-PEI can still maintain superior adsorption abilities after suffering irradiation, calcination, and immersion in strong acid. In addition, the separation performance kept excellently after five loading-washing-eluting cycles and the total adsorption ratio can still reach 97 %. Outstandingly, SiPAN-PEI can remove most of ReO 4 - from simulated nuclear wastewater through a sequential injection automatic separation system and can reduce the concentration of ReO 4 - to the maximum concentration standard set by the World Health Organization (WHO) in a short time. Leveraging density functional theory calculations and other characteristics clearly elucidated adsorption mechanism of anion-exchange between Cl- and TcO 4 -/ReO 4 -. In terms of superior adsorption property, SiPAN-PEI is demonstrated to be a pretty candidate for 99Tc elimination from wastewater. [Display omitted] • A novel resin SiPAN-PEI was successfully synthesized for selective capture of 99Tc. • SiPAN-PEI exhibited excellent adsorption ability of 99Tc in harsh conditions. • Multiple positive charge nitrogen plays a critical role in capture of 99Tc. • SiPAN-PEI demonstrated efficiency capture of 99Tc in simulated wastewater. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the physico-chemical, titration and Eu(III) adsorption/desorption characteristics of a purified Na-bentonite have been measured. Potentiometric titration at three ionic strengths (0.01, 0.1 and 0.5mol/L NaCl) at 25°C indicates that the point of zero charge (PZC) of the Na-bentonite increases with decreasing ionic strength. The parallel titration curves at three ionic strengths were interpreted by considering a layer site and two edge hydroxyl sites in the framework of surface complexation model. The adsorption/desorption of Eu(III) on the Na-bentonite was investigated by a batch experimental method. pH adsorption edges of Eu(III) in the absence and presence of CO2 at variable Eu(III) concentrations (6.74×10−8 and 3.33×10−6 mol/L) were collected and reasonably interpreted by a surface complexation model. Adsorption and desorption isotherms at pHs 4.04±0.05, 6.01±0.05, 6.53±0.05 and 7.46±0.05 indicate that the adsorption/desorption of Eu(III) on the Na-bentonite is reversible. The adsorption isotherms of Eu(III) were successfully reproduced by the proposed model. [Copyright &y& Elsevier]

The long-lived anthropogenic 129I released from human nuclear activities has been widely employed as an effective oceanographic tracer to investigate circulation of water masses in marine environment. Depth profiles of seawater collected from the Amundsen Sea Polynya, Antarctica were analyzed for total 129I and 127I, as well as their species of iodide and iodate. The measured 129I concentrations ((1.15–3.43) × 106 atoms/L) and 129I/127I atomic ratios ((0.53–1.19) × 10−11) indicate that anthropogenic 129I has not only reached the Antarctic surface marine environment but also the deep water due to a strong vertical mixing of water masses. The Circumpolar Deep Water (CDW) flowed southward along continental shelf towards the ice shelf zone (74.25°S) at a depth of 1025 m and then migrated upward and northward to the polynya and finally to the sea ice zone (71.95°S). The maximum upwelling depth of the CDW was around 200 m in the polynya. The source of 129I− in the polynya is predominantly the intrusion of source waters rather than the in-situ reduction of iodate by phytoplankton, implying a considerably slow reduction process of iodate to iodide in this region. Image 1 • Anthropogenic 129I has not only reached the Antarctic surface water but also the deep water with a depth of at least 1025 m. • The transport pathway of CDW was firstly investigated in the Amundsen Sea Polynya, and its maximum upwelling depth was around 200 m. • The reduction of iodate to iodide in the polynya might be a relatively slow process. [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]

Finding an approach for pretreatment of radionuclides from contaminated water are interesting topics of research. In present work, the ZSM-5 molecular sieve was characterized with different techniques such as zeta potential, SEM, FT-IR and XRD to clarify the surface properties of sample and applied as a sorbent to concentrate and recover Cs(I) from aqueous solution. The effect of environmental conditions such as contact time, ionic strength, content of sorbent and solution pH on Cs(I) uptake were optimized using batch techniques. Different kinetic and isotherm models were utilized to evaluate the experimental data and the correlation parameters were obtained. Based on the sorption/desorption experiment, it can be deduced that the ZSM-5 molecular sieve has potential application for the rapid and quantitative recovery of radiocesium from wastewater. [ABSTRACT FROM AUTHOR]

Technetium-99m (99mTc) is an important medical radionuclide. Due to the crisis in supply of molybdenum-99 (99Mo), production of 99mTc directly via the 100Mo (p, 2 n) reaction by cyclotron was proposed. In this process, the most critical challenge is to rapidly and efficiently separate 99mTc from high concentration of molybdenum. In this work, a novel ligand, bis(N,N -dibutyldiglycolamide)dibenzo-18-crown-6 (BisDBDGA-DB18C6) was successfully synthesized and used for extraction of TcO 4 - /ReO 4 - from molybdenum. The results demonstrated that BisDBDGA-DB18C6 expressed excellent selectivity for TcO 4 - with a high separation factor of 1.6 × 105 against Mo, a fast extraction kinetic (within 45 s), and a high extraction capacity of 211 mmol ReO 4 - (99TcO 4 -)/per mole of extractant. The extraction mechanism was proposed as a co-interaction of macrocyclic crown ether and N,N -dibutyldiglycolamide group through slope analysis, FT-IR, ESI-MS, 1H NMR titration and theory calculations. Importantly, 99Tc in the organic phase can be quantitatively (> 99%) and easily back-extracted using deionized water, which can be directly used for medical applications. [Display omitted] • A novel ligand BisDBDGA-DB18C6 was first prepared. • The tailored BisDBDGA-DB18C6 exhibits ultrafast extraction kinetic (within 45 s). • Superior extraction performance toward Tc/Re over Mo is confirmed and evaluated. • The solution is stripped with deionized water for direct medical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel adsorbent FeOOH@SiO 2 was successfully prepared and used for removal of Se(IV) and Se(VI). • FeOOH@SiO 2 shows powerful adsorption abilities for Se(IV) and Se(VI) in 3 mol/L HNO 3 system. • FeOOH@SiO 2 has excellent acid resistance, γ-irradiation and thermal stability. • Surface complexing process was proposed for Se(IV) and Se(VI) adsorption. Due to its high solubility, radioactivity and toxicity, the separation of selenium from spent fuel reprocessing waste and industrial wastewater has attracted much attention. In this study, a novel adsorbent FeOOH@SiO 2 with particle size of ∼100 μm was successfully prepared by loading FeOOH on micron-sized silica with emulsion methods. FeOOH@SiO 2 with good acid resistance, γ-irradiation and thermal stability exhibits excellent adsorption abilities for Se(IV) and Se(VI) including fast adsorption kinetics, great adsorption capacities (11.0 mg/g for Se(IV) and 6.04 mg/g for Se(VI)) and preferable adsorption selectivity. It is worth noting that FeOOH@SiO 2 can still remove nearly 90 % of Se(IV) and 80 % of Se(VI) even in 3 mol/L HNO 3 system. Combined with the observations from X-ray photoelectron spectroscopic characterization and surface potential measurement, the adsorption mechanism caused with electrostatic attraction and the formation of inner complexes for Se(IV), and reduction reaction and partial formation of outer complexes for Se(VI) can be deduced. After 4 adsorption–desorption cycles, FeOOH@SiO 2 still exhibits satisfactory reusability. Dynamic column experiments also demonstrated that FeOOH@SiO 2 exhibited excellent removal capabilities towards Se(IV) and Se(VI) from real water samples. The present work demonstrates that FeOOH@SiO 2 has great potential application for 79Se removal in highly acidic nuclear waste. [ABSTRACT FROM AUTHOR]

A simultaneous analytical method for sequential separation and determination of actinides and 90Sr in large-size environmental samples has been developed. In this method, successive co-precipitation steps were firstly conducted to remove matrix elements, then sequential column separation method was applied for simultaneous separation and purification of actinides and 90Sr/90Y. By using vacuum box technology, the total analytical time was minimized and batch processing allowed analyzing 12 samples in four days. The activity of 90Sr was obtained immediately by measuring its daughter radionuclide (90Y) with triple-to-double coincidence ratio (TDCR) Cherenkov counting, while the concentrations of Pu isotopes and 241Am could be measured by alpha spectrometry and mass spectrometric techniques. The overall recoveries of Pu, Am, Sr and Y were higher than 70% for the entire procedure, while the recovery ratios of Sr/Y were between 0.95 and 1.04 before chromatographic separation. The developed method was verified using 20 g and 50 g of environmental soil samples spiked with certified reference materials IAEA-384 or IAEA-385 and standard solution of 90Sr/90Y, and good agreement between the expected values and measured results has been achieved. • Robust method for simultaneous determination of Pu, Am and 90Sr in large-size soil samples has been developed. • XRF was utilized to quickly measure stable Y recovery. • The activity of 90Sr could be obtained by measuring its daughter radionuclide 90Y with TDCR Cherenkov counting. • The method is sufficiently sensitive for detection of global fallout signatures in soil samples. [ABSTRACT FROM AUTHOR]

Efficient and cost-effective removal of radioactive iodine anions from contaminated water has become a crucial task and a great challenge for waste treatment and environmental remediation. Herein, we present hexadecylpyridinium chloride monohydrate modified bentonite (HDPy-bent) for the efficient and selective removal of iodine anions (I− and IO 3 −) from contaminated water. Batch experiments showed that HDPy-bent could remove more than 95% of I− and IO 3 − within 10 min, and had maximum I− and IO 3 − adsorption capacities of 80.0 and 50.2 mg/g, respectively. Competitive experiments indicated that HDPy-bent exhibited excellent I− and IO 3 − selectivity in the excessive presence of common concomitant anions including PO 4 3−, SO 4 2−, HCO 3 −, NO 3 −, Cl− (maximum mole ratio of anions vs iodine anions was ∼50,000). An anion exchange mechanism was proposed for the selective adsorption of iodine anions. Optimal adsorption structure of HDPy+/I− (IO 3 −) at atomic level and driving forces of the I− (IO 3 −) adsorption were calculated by density functional theory (DFT) simulations. Moreover, the good durability and reusability of the HDPy-bent has been demonstrated with 5 adsorption-desorption cycles. Dynamic column experiment also demonstrated that HDPy-bent exhibited excellent removal and fractional recovery capabilities towards I− and IO 3 − from simulated groundwater and environmental water samples. In conclusion, this work presents a promising adsorbent material for the decontamination of radioactive iodine anions from wastewater on a large scale. [Display omitted] • HDPy-bent showed excellent adsorption abilities for iodide and iodate. • Anions exchange mechanism was confirmed by batch experiments and DFT simulations. • The pyridine N was the intrinsic active site of the modified bentonite. • HDPy-bent was efficient for removing radioiodine anions from wastewater. [ABSTRACT FROM AUTHOR]

The diffusion of iodine (labeled with 125I-) in compacted Beishan granite (BsG) was investigated using the in-diffusion capillary method at pH ~2.0 to ~11.0 under oxygen and irradiation conditions. With the advantages of simple and easy operation of the capillary diffusion devices, this work makes a preliminary investigation on the irradiation condition that cannot be performed by the traditional diffusion experiment. In this study, D a values of 125I as a tracer in the form of iodide were determined to investigate and assess the influence of irradiation and oxygen conditions, which must be considered in-situ environment of the geologic repository. The results indicate that capillary method is a simple and efficient method to study the diffusion behavior of radionuclides, which is a relatively feasible to quickly obtain the diffusion coefficient, especially for some special conditions, e.g., oxygen and irradiation conditions. The diffusion results showed that D a values of 125I- range from 1.4 × 10-10 to 1.5 × 10-9 m2∙s-1, which was much faster than other nuclides, such as 79Se (10-11 m2∙s-1). The batch adsorption experiments in this paper and related studies showed that the sorption could be neglected, i.e., 125I- is a weak adsorbent nuclide. Its diffusion and sorption process were hardly affected by pH、oxygen and irradiation conditions, which is very different from 79Se. Besides, ionic strength has a significant impact on the diffusion rate of 125I-, which is closely related to the double electric layer. Overall, this study indicates that natural BsG couldn't greatly attenuate the mobility of 125I- in the deep geologic repository and new retardation method or materials need to be explored. • The capillary method is a simple and highly efficient way to investigate some special conditions, such as γ-irradiation. • This work is the first attempt to study the influence of irradiation and oxygen conditions on I-129 diffusion using capillary method. • The diffusion of 125I- was much faster than other nuclides, which was hardly affected by irradiation and oxygen irradiation conditions. [ABSTRACT FROM AUTHOR]

The synthesis of artificial cell is a route for searching the origin of protocell. Here, we create a novel cell model of graphene capsules with selective ion channels, indicating that graphene might be an embryo of protocell membrane. Firstly, we found that the highly oxidized graphene and phospholipid-graphene oxide composite would curl into capsules under a strongly acidic saturated solution of heavy metallic salt solution at low temperature. Secondly, L-amino acids exhibited higher reactivity than D-amino acids on graphene oxides to form peptides, and the formed peptides in the influence of graphene would be transformed into a secondary structure, promoting the formation of left-handed proteins. Lastly, monolayer nanoporous graphene, prepared by unfocused 84Kr25+, has a high selectivity for permeation of the monovalent metal ions ( Rb+ > K+ > Cs+ > Na+ > Li+, based on permeation concentration), but does not allow Cl- go through. It is similar to K+ channels, which would cause an influx of K+ into capsule of graphene with the increase of pH in the primitive ocean, creating a suitable inner condition for the origin of life. Therefore, we built a model cell of graphene, which would provide a route for reproducing the origin of life. [ABSTRACT FROM AUTHOR]