The aqueous chemistry of aluminum: A new approach to high temperature solubility measurements
The solubility of boehmite, AlO(OH), has been measured as a function of pH (2 - 10, depending on ionic strength), temperature (100 - 250°C) and ionic strength (0.03 - 1 molal, NaCl) in a hydrogen-electrode concentration cell, HECC, which provided in situ measurement of hydrogen ion molality. Samples of the solution were withdrawn after the pH reading stabilized for analysis of total aluminum content by ion chromatography. Acidic or basic titrant could then be metered into the cell to affect a change in the pH of the solution. The direction of approach to the equilibrium saturated state could be readily varied to ensure that the system was reversible thermodynamically. This represents our second application of direct pH measurement to high temperature solubility studies. The results at low ionic strength are compared with those from two recently-reported high-temperature studies of boehmite solubility, which relied on the conventional batch technique. Comparisons are also made with the low temperature (<90°C) hydrolysis constants for aluminum garnered from solubility measurements with gibbsite as the stable phase. Based on these preliminary results, it is possible to draw some general conclusions concerning the relative importance of the aluminum species in solution and to reduce significantly the number of experiments needed to define this complex system in a thermodynamic sense.
- Research Organization:
- Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 889772
- Report Number(s):
- SGP-TR-151-29
- Resource Relation:
- Conference: Proceedings, Twenty-First Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, CA, January 22-24, 1996
- Country of Publication:
- United States
- Language:
- English
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