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Solubility and Surface Adsorption Characteristics of Metal Oxides to High Temperature

Description: The interaction of high temperature aqueous solutions with mineral surfaces plays a key role in many aspects of fossil, geothermal and nuclear energy production. This is an area of study in which the subsurface geochemical processes that determine brine composition, porosity and permeability changes, reservoir integrity, and fluid flow rates overlap with the industrial processes associated with corrosion of metal parts and deposition of solids in pipes and on heat exchanger surfaces. The sorption of ions on mineral surfaces is also of great interest in both the subsurface and ''above ground'' regimes of power production, playing a key role in subsurface migration of contaminants (nuclear waste disposal, geothermal brine re-injection, etc.) and in plant operations (corrosion mitigation, migration of radioactive metals from reactor core to heat exchanger, etc.). In this paper, results of the solubility and surface chemistry of metal oxides relevant to both regimes are summarized.
Date: May 4, 2001
Creator: Wesolowski, D.J.; Machesky, M.L.; Ziemniak, S.E.; Xiao, C.; Palmer, D.A.; Anovitz, L.M. et al.
Partner: UNT Libraries Government Documents Department

Microstructural Characterization of Water-Rich Boehmite (AlO(OH)): TEM Correlation of Apparently Divergent XRD and TGA Results

Description: An understanding of the solid-phase thermodynamics and aqueous speciation of aluminum is critical to our ability to understand and predict processes in a wide variety of geologic and industrial settings. Boehmite (AIO(OH)) is an important phase in the system Al<sub>2</sub>O<sub>3</sub>-H<sub>2</sub>O that has been the subject of a number of structural and thermodynamic studies since its initial synthesis [l] and discovery in nature [2]. Unfortunately, it has long been recognized that thermogravimetric analysis (TGA) of both synthetic and natural boehmite samples (that appear well crystallized by powder XRD methods) yields significant excess water - typically losing 16-16.5 wt. % on heating as compared with a nominal expected weight loss of 15.0 wt. % [3,4]. The boehmite used in our experiments was synthesized hydrothermally from acid-washed gibbsite (Al(OH)<suv>3</sub>) at 200°C. Powder XRD and SEM examination showed no evidence of the presence a contaminant phase. The TGA patterns do not suggest that this is due to adsorbed water, so a structural source is likely. We therefore undertook to examine this material by TEM to clarify this phenomenon.
Date: August 1999
Creator: Allard, L. F.; Anovitz, L. M.; Benezeth, P.; Coffey, D. W.; Palmer, D. A.; Porter, W. D. et al.
Partner: UNT Libraries Government Documents Department