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Chen D.,Soochow University of China | Chen D.,Jiangsu Higher Education Institutions | Desmond K.W.,Emory University | Weeks E.R.,Emory University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2015

We experimentally study rearranging regions in slow athermal flow by observing the flow of a concentrated oil-in-water emulsion in a thin chamber with a constricting hopper shape. The gap of the chamber is smaller than the droplet diameters, so that the droplets are compressed into quasi-two-dimensional pancakes. We focus on localized rearrangements known as "T1 events" where four droplets exchange neighbors. Flowing droplets are deformed due to forces from neighboring droplets, and these deformations are decreased by nearby T1 events, with a spatial dependence related to the local structure. We see a tendency of the T1 events to occur in small clusters. © 2015 American Physical Society. Source

Shao D.,North China Electrical Power University | Shao D.,Soochow University of China | Li J.,North China Electrical Power University | Wang X.,North China Electrical Power University | And 2 more authors.
Science China Chemistry | Year: 2014

The development of efficient materials for high extraction of uranium (UO2 2+) from seawater is critical for nuclear energy. Poly(amidoxime)-reduced graphene oxide (PAO/rGO) composites with excellent adsorption capability for UO2 2+ were synthesized by in situ polymerization of acrylonitrile monomers on GO surfaces, followed by amidoximation treatment with hydroxylamine. The adsorption capacities of PAO/rGO composites for UO2 2+ reached as high as 872 mg/g at pH 4.0. The excellent tolerance of these composites for high salinity and their regeneration-reuse properties can be applied in the nuclear-fuel industry by high extraction of trace UO2 2+ ions from seawater. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg. Source

Shu X.,Soochow University of China | Wang Y.,Soochow University of China | Zhang S.,Soochow University of China | Huang L.,Soochow University of China | And 3 more authors.
Talanta | Year: 2015

Uranyl ion exists at trace levels in the environment and can cause severe adverse effects to human health. Therefore, it is desirable to develop analytical methods that can determine the trace uranyl ion in aqueous medium. We report here a new method using a thermo-responsive polymeric fluorescent sensor. Specifically, 5,10,15,20-tetrakis(4-carboxyphenyl)-porphyrin terminated poly(N-isopropylacrylamide) (TCPP-PNIPAM) was synthesized by controlled free radical polymerization for the detection of uranyl ion. The maximum fluorescence intensity at ~658 nm of TCPP-PNIPAM increases with molecular weights and is also closely related to the temperature. The polymeric sensor is sensitive to pH (1.0~5.0) with a fast responsive time (~3 min). Under optimized experimental conditions, the sensor exhibits a stable response for uranyl ion with high selectivity over a concentration range from 1.0×10-3 to 1.0×10-7 mol/L. For the trace uranyl ion (such as 1.0×10-8 or 10-9 mol/L), the determination could be successfully achieved after concentrating 100 times by centrifugation above 32 °C. The properties enable the polymeric sensor to have great potential for environmental application. © 2014 Elsevier B.V. All rights reserved. Source

Sun Y.,North China Electrical Power University | Sun Y.,Jiangsu Higher Education Institutions | Yang S.,North China Electrical Power University | Chen Y.,Kyoto University | And 3 more authors.
Environmental Science and Technology | Year: 2015

The adsorption and desorption of U(VI) on graphene oxides (GOs), carboxylated GOs (HOOC-GOs), and reduced GOs (rGOs) were investigated by batch experiments, EXAFS technique, and computational theoretical calculations. Isothermal adsorptions showed that the adsorption capacities of U(VI) were GOs > HOOC-GOs > rGOs, whereas the desorbed amounts of U(VI) were rGOs > GOs > HOOC-GOs by desorption kinetics. According to EXAFS analysis, inner-sphere surface complexation dominated the adsorption of U(VI) on GOs and HOOC-GOs at pH 4.0, whereas outer-sphere surface complexation of U(VI) on rGO was observed at pH 4.0, which was consistent with surface complexation modeling. Based on the theoretical calculations, the binding energy of [G⋯UO2]2+ (8.1 kcal/mol) was significantly lower than those of [HOOC-GOs⋯UO2]2+ (12.1 kcal/mol) and [GOs-O⋯UO2]2+ (10.2 kcal/mol), suggesting the physisorption of UO22+ on rGOs. Such high binding energy of [GOs-COO⋯UO2]+ (50.5 kcal/mol) revealed that the desorption of U(VI) from the -COOH groups was much more difficult. This paper highlights the effect of the hydroxyl, epoxy, and carboxyl groups on the adsorption and desorption of U(VI), which plays an important role in designing GOs for the preconcentration and removal of radionuclides in environmental pollution cleanup applications. © 2015 American Chemical Society. Source

Qian J.,Soochow University of China | Zhang S.,Soochow University of China | Zhou Y.,Soochow University of China | Dong P.,Soochow University of China | And 2 more authors.
RSC Advances | Year: 2015

Uranium(VI) may pose a great threat to human health and the environment owing to its high chemical toxicity and radioactivity. A novel method is reported herein to synthesize surface ion-imprinted magnetic microspheres (SII-MM) for efficient removal of uranium(VI). Specifically, uranyl ion-imprinted polymer-functionalized Fe3O4@SiO2 microspheres were prepared by surface-locating copolymerization of N-hydroxyethylacrylamide and 1-vinylimidazole. The effects of chemical composition, pH, adsorbent dose, competing ions and initial concentration on the adsorption of uranyl ions were evaluated. The exothermic spontaneous adsorption kinetically followed a pseudo-second-order model, and the process of SII-MM could reach equilibrium with a capacity of 146.41 mg of U per g within 1.0 min at pH 5.0 and 298.15 K. Compared with non-imprinted composites, SII-MM showed higher selectivity, faster kinetics, and larger capacity for uranyl adsorption. This work indicates that the SII-MM can be used as a promising adsorbent to effectively remove uranium(VI) from aqueous solutions. © The Royal Society of Chemistry 2015. Source

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