Effects of Mineral Compositions on Matrix Diffusion and Sorption of 75Se(IV) in Granite.

Exploring the migration behaviors of selenium in granite is critical for the safe disposal of radioactive waste. The matrix diffusion and sorption of 75Se(IV) (analogue for 79Se) in granite were systematically studied to set reliable parameters in this work. Through-diffusion and batch sorption experiments were conduct with four types of Beishan granite. The magnitudes of the obtained apparent diffusion coefficient (Da) values are of the following order: monzogranite > granodiorite-2 > granodiorite-1, which is opposite to the sequence of the Kd values obtained from both the diffusion model and batch sorption experiments. The EPMA results of the granitic flakes showed that there was no obvious enrichment of Se(IV) on quartz, microcline and albite. Only biotite showed a weak affinity for Se(IV). Macroscopic sorption behaviors of Se(IV) on the four types of granite were identical with the sequence of the granitic biotite contents. Quantitative fitting results were also provided. XPS and XANES spectroscopy data revealed that bidentate inner-sphere complexes were formed between Se(IV) and Fe(III). Our results indicate that biotite can be representative of the Se(IV) sorption in complex mineral assemblages such as granite, and the biotite contents are critically important to evaluate Se(IV) transport in granite.

Synthesis of Cu/Cu2O hydrides for enhanced removal of iodide from water.

In order to improve the removal capacity of Cu2O for I- anions from water, Cu/Cu2O hybrids have been synthesized through a facile hydrothermal route, characterized by using SEM, XRD, XPS, and applied to remove I- anions under different experimental environments. The results demonstrate that the Cu content and morphology of samples can be tuned by the adding amount of ammonia. Meanwhile, the possible crystalline mechanism, Cu2O formed firstly and then metallic Cu generated, was presented. With the increasing of Cu doped amount, the removal capacity of Cu/Cu2O hybrids increased significantly from 0.02mmolg-1 to 0.18mmolg-1. Furthermore, a reaction mechanism of I- anions and Cu2O, which generated from the disproportionation reaction of metallic Cu and CuO, has been proposed according to the characterization analyses of the composites before and after adsorption, explaining the highly efficient removal of I- anions. In addition, Cu/Cu2O hybrids showed excellent selectivity for I- anions in the presence of large concentrations of competitive anions such as SO42- and NO3- and could work in an acidic and neutral environment. This study is hopefully to prompt Cu2O to grow up to be a new and highly efficient adsorbent for the removal of iodide from solutions.

Ionic liquids as modifiers to improve the separation efficiency of nonaqueous capillary electrophoresis with high electric field strengths.

A method of nonaqueous capillary electrophoresis based on ionic liquids was developed with a high electric field (800 V/cm). The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate was used as modifier to improve the separation efficiency; trishydroxymethylaminomethane and sodium cholate were used as background electrolytes in methanol and acetonitrile. The ionic liquids used in this paper have the ability to assist in the separation of hydrophobic mixtures while maintaining adequate background current. They can also improve the efficiency of heat diffusion in the capillary because they demonstrate high thermal conductivity. The developed method was used to analyze kaempferol-3-O-glucoside, 7-hydroxy-8-methoxycoumarin and 8-hydroxycoumarin-7-O-glucoside in samples of Sinacalia tangutica. The obtained quantities of the three analytes in the flower of Sinacalia tangutica were 0.27, 0.18 and 0.57%, respectively. The recovery was determined with standard addition and the results were 85.1-100.4%.