Chemical Thermodynamics Of Selenium

In order to quantitatively predict the chemical reactions that hazardous materials may undergo in the environment, it is necessary to know the relative stabilities of the compounds and complexes that may be found under certain conditions. This type of calculations may be done using consistent chemical thermodynamic data, such as those contained in this book for inorganic compounds and complexes of selenium. * Fully detailed authoritative critical review of literature.* Integrated into a comprehensive and consistent database for waste management applications.* CD ROM version.

There are a number of impurity elements present in sulphide ores that can have a deleterious effect on the properties of the final copper metal product. In this thesis, an equilibrium distribution technique was used to determine the thermodynamic behaviour of selenium and tellurium in molten slags used in copper production. Calcium ferrite based slags and copper or silver alloy were equilibrated in magnesia crucibles at temperatures of 1200 to 1400 °C and oxygen partial pressures of 10-11 to 10-0.68 atm. Under conditions typical of those employed during copper converting, the minor elements were found to enter the slag as negatively charged species. The partitioning of selenium and tellurium to the slag was greatest at high temperature, low oxygen partial pressure and at highest concentration of basic oxide (CaO or BaO). The experimentally derived data were combined with published information to calculate the selenide and telluride capacities of the slag, and also to generate fundamental thermodynamic activity data for selenium and tellurium in the slag phase. It was found that the activity coefficients of selenium and tellurium were independent of their concentration in the slag over the range studied, but were strongly dependent on the temperature, slag chemistry and oxidation state of the slag. Experiments were also designed and carried out to determine what effect the presence of iron oxide and its oxidation state has on the behaviour of selenium in the slag. A series of experiments involving iron oxide additions to a calcium aluminate slag was conducted under increasingly oxidising conditions to assess the effect of total iron on the selenide capacity as the dominant oxidation state of iron in the slag changed. It was shown that at a constant ratio of CaO:Al2O3, the selenide capacity increased with total iron in the slag. However, the effect on the selenide capacity did not appear any more significant as the Fe3+:Fe2+ ratio changed in a particular direction. 4 Another series of experiments was carried out with iron calcium silicate slags to determine the stability of phases within the slag, and how this affected the equilibrium distribution and activity coefficient of selenium in the slag. A number of solid phases were identified and their composition determined by scanning electron microscopy, energy dispersive spectroscopy and electron microprobe analysis. The composition and minor element content of the remaining liquid was calculated using a thermodynamic model. From this it was found that the capacity of the liquid slag has a region of independence against slag chemistry, before increasing strongly with increasing lime content to the calcium ferrite composition. Some of the implications of this work are discussed with reference to the practicality of adjusting the process variables in a large-scale industrial process for the purpose of managing minor element content of the molten phases. Considerations include the effect on copper recovery and rate of wear of furnace refractory materials.

The Chemistry of Sulfur, Selenium, Tellurium and Polonium deals with the chemistry of sulfur, selenium, tellurium, and polonium. The history, occurrence and distribution, and production of all four elements are discussed, along with their industrial uses, purification, and allotropy; nuclear, physical, and chemical properties; and biological activities. Comprised of two chapters, this volume begins with an overview of the history, occurrence and distribution, and production of sulfur, selenium, tellurium, and polonium, as well as their industrial uses, purification, and allotropy; nuclear, physical, and chemical properties; and biological activities. The compounds of all four elements are also considered, including sulfanes, sulfur halides, oxides and oxyacids, and compounds composed of sulfur, nitrogen, and halogen; peroxides, hydroxides and oxo-acids, sulfides, nitrides and azides, carbon selenides and tellurides; carbonates, salts of organic acids, alkoxides, nitrates, phosphates, chromates, halates and perhalates, and organo-compounds. This book will be of interest to inorganic chemists as well as students and researchers in the field of inorganic chemistry.

This volume is part of the series on "Chemical Thermodynamics", published under the aegis of the OECD Nuclear Energy Agency. It contains a critical review of the literature on thermodynamic data for compounds of complexes of oxalate, citrate, EDTA and iso-saccharinate with uranium, neptunium, plutonium, americium, technetium, selenium, nickel and zirconium. A review team, composed of five internationally recognized experts, has critically reviewed all the scientific literature containing chemical thermodynamic information for the above mentioned systems. The results of this critical review carried out following the Guidelines of the OECD NEA Thermochemical Database Project have been documented in the present volume, which contains tables of selected values for formation and reaction thermodynamical properties and an extensive bibliography. Contributed by: Wolfgang Hummel (Chairman), Paul Scherrer Institute, Switzerland, Giorgio Anderegg, Swiss Federal Institute of Technology (ETH), Switzerland, Linfeng Rao, Lawrence Berkeley National Laboratory, U.S.A., Ignasi Puigdomènech, Swedish Nuclear Fuel and Waste Management Co. (SKB), Sweden, and Osamu Tochiyama, Tohoku University, Japan. * Critical review of all literature on chemical thermodynamics for compounds and complexes of oxalate, citrate, EDTA and iso-saccharinate with U, Np, Pu, Am, Tc and Se, Ni and Zr. * Tables of recommended Selected Values for thermochemical properties * Documented review procedure * Exhaustive bibliography * Intended to meet requirements of radioactive waste management community * Valuable reference source for the physical, analytical and environmental chemist.

This volume is part of the series on "Chemical Thermodynamics", published under the aegis of the OECD Nuclear Energy Agency. It contains a critical review of the literature on thermodynamic data for inorganic compounds of zirconium. A review team, composed of five internationally recognized experts, has critically reviewed all the scientific literature containing chemical thermodynamic information for the above mentioned systems. The results of this critical review carried out following the Guidelines of the OECD NEA Thermochemical Database Project have been documented in the present volume, which contains tables of selected values for formation and reaction thermodynamical properties and an extensive bibliography. * Critical review of all literature on chemical thermodynamics for compounds and complexes of Zr.* Tables of recommended Selected Values for thermochemical properties* Documented review procedure* Exhaustive bibliography* Intended to meet requirements of radioactive waste management community* Valuable reference source for the physical, analytical and environmental chemist.

This is the second volume in a series of critical reviews of the chemical thermodynamic data of those elements of particular importance in the safety assessment modeling of high-level radioactive waste storage and disposal facilities. The objective of these reviews is to provide a set of reliable thermodynamic data that can be used to describe the behaviour of these elements under conditions relevant for radioactive waste disposal systems and the geochemical environments. The present volume is a review of experimental data reported in the literature for americium. On a few occasions, where no data existed, comparisons and estimates were made based on experimental data on analog lanthanide elements. The basic philosophy was to develop a minimum set of solid phases and solution species of americium that would fit all experimental data being reviewed.