Chemical state

About: Chemical state is a research topic. Over the lifetime, 2378 publications have been published within this topic receiving 78183 citations.

A Study on the Chemical Forms and Migration Behavior of Carbon-14 Leached from the Simulated Hull Waste in the Underground condition

Abstract: The chemical forms of carbon leaching from carbon-containing Zr and Fe-based metallic materials have been investigated to improve the estimation of the contribution of C-14 in the performance assessment of TRU waste disposal. Both organic and inorganic carbons were identified in the leached solution with carbon containing zirconium and steel, and the concentrations of total carbon (organic plus inorganic) in the leached solutions increased with time. The carbon concentrations in the leached solution for both metallic samples were higher at higher pH. With High Performance Liquid Chromatography (HPLC), organic carbons were identified to be low-molecular weight alcohols, carboxylic acids and aldehydes. To explore the chemical state of carbon in the matrix materials, the leaching experiments were carried out also for ZrC, Fe3C, the powder mixtures of carbon and zirconium, and of carbon and iron. The low-molecular weight organic carbons were detected only in the case of carbides (ZrC and Fe3C). The chemical forms of carbon in the zirconium alloy were suggested to be carbide or carbon by H.D. Smith[1]. The present result suggests that the chemical forms of carbon in zirconium or iron are mainly in the form of carbide. In the interest of performance assessment, the distribution coefficients of the organic carbon species identified in the leached solution for cement were obtained. As expected, some of them were shown to be larger than the values assumed in the performance assessment of Progress Report on Disposal Concept for TRU Waste in Japan[2].

Porous Nanobimetallic Fe-Mn Cubes with High Valent Mn and Highly Efficient Removal of Arsenic(III).

Abstract: Iron (Fe) oxides are the most commonly used adsorbent materials for the aqueous removal of Arsenic (As), but they have deficiencies, including low uptake and poor removal of the relatively higher toxicity As(III). Introduction of transition metals into Fe-containing adsorbents, an inexpensive method of altering Fe chemical states, is likewise of interest for removing As(III) from water by means of adsorption. Porous cubic Fe–Mn structures with BET surface area of 450 m2 g–1 were herein prepared via chemical etching of Mn-substituted Prussian Blue analogues (PBAs). Cyclic voltammetry showed a “protective” role of polyvinylpyrrolidone (PVP) during the preparation process, so that Mn with high valence state was readily preserved in this binuclear corner-sharing structure. The calculated reaction Gibbs free energy, which was the most negative of the studied adsorbents, indicated that the adsorption was promoted in the presence of high valence Mn. The structures were capable of directly capturing As(III) oxyan...

Synthesis and antibacterial property of Ag-containing TiO2 coatings by combining magnetron sputtering with micro-arc oxidation

Abstract: The present work was aimed at developing the antibacterial Ag-containing TiO 2 coatings on titanium by combining magnetron sputtering with micro-arc oxidation (MAO). The surface morphology, microstructure, chemical composition and chemical state of the Ag-containing TiO 2 layers were characterized using scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The concentration of Ag in the sputtering-deposited AgTi layer on pure titanium was 13.9 wt.%. The MAO coatings were prepared on the AgTi layers under different oxidation duration of 2, 5 and 8 min. The size of the well-separated pores increased by increasing the oxidation duration. Metal Ag existed as Ag 0 state was mainly distributed homogeneously inside the pores and the concentrations were 2.36, 2.05 and 1.50 wt.%, respectively. The main TiO 2 phases bearing Ca and P species appeared within the structure of the coatings were rutile and anatase. The Ag-containing coating oxidation for 5 min showed excellent antibacterial activity of Escherichia coli ( E.coli ) within 24 h and the antibacterial rate gradually raised with increasing contact time.