ISSN:
1572-8927
Keywords:
Titatium(IV) oxide
;
rutile
;
aqueous solutions
;
metal ion hydrolysis
;
phosphatocomplexing
;
equilibrium constant
;
thermodynamics
;
pressurized water
;
hydrothermal solutions
;
corrosion
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A platinum-lined, flowing autoclave facility was used to investigate the solubility behavior of titanium dioxide (TiO2) in aqueous sodium phosphate, sodium hydroxide and ammonium hydroxide solutions between 17 and 288°. Baseline Ti(IV) solubilities were found to be on the order of one nanomolal, which were enhanced by the formation of anionic hydroxo- and phosphato-complexes. The measured solubility behavior was examined via a titanium(IV) ion hydrolysis/complexing reaction equilibria were obtained from a least squares analysis of the data. The existence of three new Ti(IV) ion complexes is reported for the first time: Ti(OH)4(HPO4)2−, Ti(OH)5(H2PO4)2− and Ti(OH)5(HPO4)3−. The triply-charged anionic complex was the dominant Ti(IV) species in concentrated, alkaline phosphate solutions at elevated temperatures. This complex is expected to exhibit C.N.=4 (i.e., Ti(OH)2OPO 4 3− ). A summary of thermochemical properties for species in the systems TiO2-H2O and TiO2-P2O5-H2O is also provided.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00646781
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