ISSN:
1572-8927
Keywords:
Arsenic hydroxide complexes
;
arsenolite
;
solubility
;
Raman spectroscopy
;
hydration
;
organic compound–water solutions
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Solubilities of arsenolite (As2O3, cub.) were measured from 22 to 90°C in water–acetone, water–acetic acid, and water—formic acid solutions of compositions ranging from the pure organic compound to pure water. Raman spectra were obtained at ambient temperature on As-containing water–acetic acid and water–acetone solutions. Results show that arsenic solvation by these organic compounds is negligible and hydroxide species dominate As speciation over a wide range of water activity (aH 2 O〉 0.01). The solubility data were analyzed using an approach based on stoichiometric hydration reactions. Results show that As2O3 solubility can be described as a function of water activity, independently of the nature of the organic compound, by involving two neutral As hydroxide complexes: As(OH)3 and As(OH)3·4H2O. Stability constants derived for these species indicate that hydration weakens with increasing temperature. Calculations using these constants show that at low temperatures the tetrahydrate As(OH)3·4H2O is dominant in water-rich solutions; by contrast, in high-temperature crustal fluids, As(OH)3 becomes the major As species. The proposed hydration model can be used to analyze solubility of arsenic-bearing minerals and arsenic transport in complex H2O–CO2—electrolyte solutions encountered in natural and industrial environments.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1021795924067
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