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Bentonite was irradiated with 60Co γ-rays at a dose rate of 10 kGy/h to achieve irradiation doses of 1, 2, 3 MGy and was characterized to evaluate its stability before and after irradiation and understand the radiation damage mechanism. The structure of the bentonite was slightly affected by high doses of irradiation, and the U(VI) adsorption capacity of the irradiated bentonite was reduced compared to that of raw bentonite. Overall, this study provides insights into the negative effects of high-dose γ-ray irradiation on the stability and adsorption capacity of bentonite, which has safety implications for the storage of radioactive waste. [ABSTRACT FROM AUTHOR]

An organic compound adsorbent is prepared by modifying acid-activated bentonite with cetyltrimethylammonium bromide (CTAB). The physical and chemical properties of the samples before and after modification are characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and zeta potential analysis. A batch static adsorption experiment is used to study the adsorption properties of Cs+ before and after modification. Results show that the times to reach the adsorption equilibrium of bentonite before and after modification are 12 h and 2 h, respectively, and the adsorption rates are 26% and 85%, respectively. Different types of ions have different effects on adsorption. Pseudo-first-order and pseudo-second-order kinetic simulations and adsorption isotherm simulations are carried out with the data, and the adsorption capacities of the two adsorbents for Cs+ are 4.8 mg/g and 22.6 mg/g, respectively. The calculated thermodynamic parameters show that the adsorption is endothermic and spontaneous. [ABSTRACT FROM AUTHOR]

Montmorillonite colloid was synthesized and characterized and the adsorption of U(VI) on colloid as a function of contact time, temperature, initial concentration of U(VI) solution, pH and foreign ions was investigated through batch experiments. The results illustrate that the adsorption reaches equilibrium quickly within 30 mins. Results showed that the absorption process is influenced by pH value, temperature and ions, among which pH value is the most significant. Adsorption percentage increases obviously at pH = 4.0–7.0, and then decreases with the increase of pH value. The competitive cations also inhibit the adsorption. pH value and ions affect the surface properties and charges of the colloid and the chemical form of nuclides. The experimental data was analyzed in detail. The maximum adsorption capacity obtained by fitting the second-order kinetic model is very close to the experimental data. The Langmuir model fits the experimental data better than Freundlich models, R2 = 0.991. The results of fitting two adsorption isotherms show that the adsorption of colloids on uranium has both physical and chemical adsorption, and is mainly monolayer adsorption. Furthermore, the adsorption process is a spontaneous endothermic reaction by calculating the thermodynamic parameters. This experiment can provide some data basis for the adsorption study of U(VI) on colloids. [ABSTRACT FROM AUTHOR]

An organic compound adsorbent is prepared by modifying acid-activated bentonite with cetyltrimethylammonium bromide (CTAB). The physical and chemical properties of the samples before and after modification are characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and zeta potential analysis. A batch static adsorption experiment is used to study the adsorption properties of Cs+ before and after modification. Results show that the times to reach the adsorption equilibrium of bentonite before and after modification are 12 h and 2 h, respectively, and the adsorption rates are 26% and 85%, respectively. Different types of ions have different effects on adsorption. Pseudo-first-order and pseudo-second-order kinetic simulations and adsorption isotherm simulations are carried out with the data, and the adsorption capacities of the two adsorbents for Cs+ are 4.8 mg/g and 22.6 mg/g, respectively. The calculated thermodynamic parameters show that the adsorption is endothermic and spontaneous. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hollow structure was synthesized via one-pot self-assembly without templates. • P(Cr)E-7 exhibited high maximum U(VI) adsorption of 282.8 mg/g and stability at pH = 1.0. • P(Cr)E-7 presented a pH-dependent selective adsorption for U(VI) (23 % at pH = 2.0, 60% at pH = 1.0). • The mechanism of positively charged species exchange promoted coordination adsorption is revealed. Efficient removing uranium (U(VI)) from highly acidic environment remain a great challenge for the adsorbent. Herein, a novel hollow phytic acid-based hybrid material (P(Cr)E-7) was synthesized by a mild facile one-pot self-assembly method without template choosing Cr3+, phytic acid (PA) and ethylenediamine (EDA) as the inorganic and two organic building blocks. P(Cr)E-7 was employed for U(VI) capture in highly acidic wastewater. Thanks to the flexible segment assembled from EDA and PA, and the strong affinity of PA to U(VI), the maximum adsorption capacity of P(Cr)E-7 for U(VI) reached 282.8 mg/g under the condition of pH = 1.0 in static adsorption experiment. Simultaneously, P(Cr)E-7 showed the selectivity efficiency of almost 100 % for An-Ln and pH-dependent selectivity efficiency of 60 % for U(VI) in multi-ions solution with pH = 1.0. Moreover, P(Cr)E-7 showed excellent stability in 0.1 M HNO 3 and reusability after three cycles at pH = 1.0 benefiting from stable segment from coordination of Cr(III) and PA. Additionally, the SEM, XRD, FTIR, and XPS analysis revealed the adsorption mechanism that U(VI) exchanges with positively charged EDA+/EDA2+in P(Cr)E-7 to obtain preferred coordination geometry and ligand environment and further coordinates with P-OH/P = O in PA. This study addresses the practical application of effective adsorption of uranium in highly acidic nuclear industrial wastewater and illustrated a novel material design strategy of adsorbents for uranium extraction. [ABSTRACT FROM AUTHOR]