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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]

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]

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]

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]

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]