Journal of Inorganic and Nuclear Chemistry最新文献

Thermodynamic parameters for in-water-formation of mononuclear complexes of cadmium-halide-thiourea systems, calculated by means of potentiometric measurements at different temperatures and at μ = 1 for KNO₃, are reported.

The stability of β-Cs₂U₂O₇ and SrZrO₃, two possible phases of spent fuel elements, in hydrothermal fluids was investigated. β-Cs₂U₂O₇ was unstable under hydrothermal conditions of 100, 200 and 300°C/300 bars releasing substantial amounts of its Cs in deionized water and all of its Cs in a bittern (high-Mg and-Ca) brine. SrZrO₃ was found to be quite stable in deionized water but not in a bittern brine. For example, Sr released into solution decreased from 3.9 to 2.8% with an increase in temperature from 100 to 300°C probably because of better crystallization of SrZrO₃ at higher temperatures. In bittern brine, 23.3, 94.9 and 100% of Sr was released into solution at 100, 200 and 300°C respectively as a result of acidic conditions generated by the hydrolysis of MgCl₂ and formation of brucite. These results suggest that bittern brine which may be encountered in a salt repository is highly corrosive and may release all the Cs and Sr into solution under hydrothermal conditions if the containment were breached. The use of tailor-made overpacks or backfill barriers of highly stable and sorptive materials is essential especially in a salt repository in order to minimize the threat of highly hazardous Cs and Sr radionuclides finding their way into ground waters.

Equilibria of cobalt(II) perchlorate with lithium chloride in 0.1 M LiClO₄ acetone solution have been investigated by means of potentiometry and spectrophotometry at 25.0°C. By the addition of a large excess of medium salt (LiClO₄), the ionic dissociation of electrolytes are surpressed and the ion-pairs predominate in this medium. It was confirmed that AgAgCl electrode gives rise to the Nernstian response in this medium. The potentiometry reveals the formation of following chloro complexes of cobalt (II): $\text{Co(ClO}{}_4\text{)}{}_2\text{+LiCl}\text{⇌}\text{K}{}_1\text{CoCl(ClO}{}_4\text{)+LiClO}{}_4$$\text{Co(ClO}{}_4\text{)+LiCl}\text{⇌}\text{K}{}_2\text{CoCl}{}_2\text{+LiClO}{}_4$$\text{CoCl}{}_2\text{+LiCl}\text{⇌}\text{K}{}_3\text{LiCoCl}{}_3$

Successive formation constants were determined as log K₁ = 5.0 ± 0.3, log K₂ = 6.2 ± 0.3 (log β₂ = log K₁K₂ = 11.15 ± 0.03) and log K₃ = 5.97 ± 0.03. By the spectrophotometric titration at higher concentration of lithium chloride, we have the following equilibrium: $\text{LiCoCl}{}_3\text{+LiCl}\text{⇌}\text{K}{}_4\text{LiCoCl}{}_3$ with formation constant of log K₄ = 2.64 ± 0.05. Absorption spectra of these complexes are presented.

Acid dissociation constants of epimeric threonines (Thr, allo-Thr) and isoleucines (Ile, allo-Ile) and the stability constants of their complexes with Co²⁺ and Cu²⁺ were determined by potentiometry. The natural epimers form more stable complexes than the allo forms. C.d. spectra of the complexes investigated were recorded, resolved into component bands and assigned.

Electronic absorption spectra of Fe(III) in some phosphate glasses have been measured at room and near liquid-nitrogen temperatures, in the energy range 11,500–30,000 cm⁻¹. Assuming cubic-field microsymmetry, and taking no account of spin-orbit coupling, it was found that the energies of the five observed bands are accounted for satisfactorily in terms of single values of B, C and Δ using the free-atom representation of the crystal-field theory, provided that a Trees' correction is included. It was found that the simple strong-field representation gives less satisfactory results. The Racah parameters, B and C, were evaluated for Fe(III) in two different phosphate media without a pre-assigned value of the fraction C/B and an empirical value of C/B = 3.60 was determined and applied to other data in the literature.