Experimental studies of aluminum solubility and speciation in brines
The solubility of gibbsite -- Al(OH){sub 3} -- has been measured in (a) Na{sup +}-H{sup +}-Al{sup 3+}-Cl{sup {minus}} brines to 70{degrees}C and 5 molal ionic strength; (b) Na{sup +}K{sup +-}OH{sup {minus}}-Cl{sup {minus}}-Al(OH){sub 4}{sup {minus}} brines to 80{degrees}C and 5 molal; and (c) at 50{degrees}C in 0.1 molal NaCl with the H{sup +} concentration controlled by acetate, bis-tris and tris buffers at -log[H{sup +}] -- 3 to 9. The activity coefficient ratios, ({gamma}Al{sup 3+})/({gamma}H{sup +}){sup 3} and ({gamma}Al(OH){sub 4}{sup {minus}})/({gamma}OH{sup {minus}}), have been modeled in the 0--100{degrees}C range using the Pitzer ion interaction treatment. Complexes of Al{sup 3+} with acetate and Al(OH){sub 4}{sup {minus}} with bis-tris have been identified. Our results indicate that complexation of Al{sup 3+} by chloride is insignificant in this temperature range. The formation constants of Al(OH){sup 2+} have been quantitatively determined by potentiometric titrations in the range 25--125{degrees}C and 0--5 molal ionic strength in NaCl media. After correcting for complexation of aluminum ions with the buffers, our solubility data at near neutral pH`s are shown to be in quantitative agreement with the potentiometric results.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 10135383
- Report Number(s):
- CONF-920761--4; ON: DE92010448
- Country of Publication:
- United States
- Language:
- English
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