The nucleation kinetics of calcium sulfate dihydrate in NaCl solutions up to 6 m and 90 C
- Rice Univ., Houston, TX (United States). Dept. of Environmental Science and Engineering
The crystallization of calcium sulfate from aqueous solutions with NaCl is both geological and industrial interest because NaCl is the dominant solute in natural brines and many industrial fluids. Induction periods for the nucleation of calcium sulfate dihydrate were experimentally determined as a function of supersaturation in NaCl solutions from 0 to 6 m at 25 C and in 3.0-m NaCl solutions at temperatures from 25 to 90 C. Using classic nucleation theory, the interfacial tension between gypsum and 3.0-m NaCl solution was estimated to be about 39 mJ/m[sup 2] at 25 C and increases with increasing temperature (to 63 mJ/m[sup 2] at 90 C). It was observed that the induction period decreases with increasing NaCl concentrations up to 3 m and then starts to increase slightly at a given temperature and saturation state. The electrolyte effect on nucleation was proportional to the enhanced solubility of calcium sulfate dihydrate in NaCl solutions. This phenomenon may result from decreased crystal-solution interfacial tensions caused by increased gypsum solubility in electrolyte solutions. Although anhydrite is the thermodynamically stable phase at elevated temperatures and in concentrated solutions, only gypsum was nucleated.
- OSTI ID:
- 7206183
- Journal Information:
- Journal of Colloid and Interface Science; (United States), Journal Name: Journal of Colloid and Interface Science; (United States) Vol. 162:2; ISSN 0021-9797; ISSN JCISA5
- Country of Publication:
- United States
- Language:
- English
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ALKALI METAL COMPOUNDS
AQUEOUS SOLUTIONS
BRINES
CHLORIDES
CHLORINE COMPOUNDS
CONCENTRATION RATIO
DISPERSIONS
GEOTHERMAL WELLS
GYPSUM
HALIDES
HALOGEN COMPOUNDS
MINERALS
MIXTURES
OIL WELLS
SCALING
SODIUM CHLORIDES
SODIUM COMPOUNDS
SOLUBILITY
SOLUTIONS
SULFATE MINERALS
WATER TREATMENT PLANTS
WELLS