Kinetic studies final quarterly report
In this report, we present equations for the functional dependence of the rates of gibbsite dissolution of and precipitation on {Delta}G of the reaction at 80{degrees}C and pH 3. We have obtained one more dissolution data point which better defines the shape of the dissolution rates vs {Delta}G curve. Theoretical calculations and scanning electron photomicrographs suggest that the sudden increase in dissolution rate at {Delta}G = {minus}0.250 kcal/mol may be related to the critical undersaturation necessary for the formation of etch pits. Of three more experiments carried out to measure simultaneous precipitation rates of gibbsite and kaolinite, one worked well mechanically and therefore, provided acceptable results. This particular experiment extended the range of kaolinite supersaturation previously achieved by over 100%. A rate was obtained at a {Delta}G of {approximately}1.3 kcal/mol or 5X saturation, and this rate was only twice that at 2X saturation. These two combination experiments which have functioned well mechanically yield gibbsite rates that agree extremely well with the single phase rates, and kaolinite rates which are also compatible with the previously obtained rates. Results from experiments on albite dissolution and precipitation at 80{degrees}C in buffered pH {approximately} 8.8, 0.1 m NaCl solutions are starting to define the dependence of those rates on {Delta}G. Dissolution at {Delta}G = {minus}6 kcal/mol is congruent and agrees with the results of Knauss and Wolery. However, the data closer to equilibrium define a curve which indicates that this dissolution rate may not be the far-from-equilibrium rate. Recent progress on the dissolution precipitation kinetics of silica phases is also reported. 12 refs., 30 figs., 8 tabs.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5848064
- Report Number(s):
- UCRL-CR-106778; ON: DE91012039
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
ALBITE
ALUMINIUM COMPOUNDS
ALUMINIUM HYDROXIDES
ALUMINIUM SILICATES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
DISSOLUTION
DOCUMENT TYPES
ELECTRON MICROSCOPY
FELDSPARS
GIBBSITE
HYDROGEN COMPOUNDS
HYDROXIDES
KAOLINITE
KINETICS
MICROSCOPY
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PRECIPITATION
PROGRESS REPORT
REACTION KINETICS
SCANNING ELECTRON MICROSCOPY
SEPARATION PROCESSES
SILICA
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES