Partitioning of uranium in contaminated bottom sediments: The meaning of fractionation.

Sequential extraction tests were used to study partitioning of U in the bottom sediments of two reservoirs that have been used for the temporary storage of nuclear waste at the "Mining and Chemical Combine" (Zheleznogorsk, Krasnoyarsk region, Russia). Various sequential extraction protocols were applied to the bottom sediment samples and the results compared with those obtained for laboratory-prepared simulated samples with different speciation and partitioning, e.g., U(VI) sorbed onto various inorganic minerals and organic matter, as well as uranium oxides. The distributions of uranium in fractions extracted from simulated and actual contaminated samples were compared to shed light on the speciation of U in the bottom sediments. X-ray absorption spectroscopy, X-ray diffraction, and scanning electron microscopy were also used to analyze the partitioning of U in contaminated sediments. We also compared the results obtained using the spectroscopic and microscopic techniques, as well as sequential extraction.

Ionic liquids based on quaternary phosphonium cation as active components of solid-state iodide selective electrode.

The two ionic liquids (ILs) which melt above room temperature were used as active components of solid-state ion-selective electrodes (ISEs). The both ILs are composed of quaternary phosphonium cation and fluorinated anion, namely bis(trifluoromethylsulfonyl)imide and hexafluorophosphate. Molten and then solidified ILs were used to cover solid-state screen printed electrodes with an ion-sensing layer. The sensors show the response towards iodide. The addition of tetrakis(tert-butyl)phthalocyaninatocobalt (III) iodide to ion-sensing composition significantly improved the operational characteristics. The resulting ISE demonstrates good sensitivity and detection limit: S=-(58.0 ± 0.8) mV/dec, C(min)=6 × 10(-5)М; response time is ca. 15s. A high selectivity towards iodide over number anions is observed. The ISE could be used for at least a month without any deterioration of signal.