Direct Observations of Nonintegral Hydrous Ferric Oxide Solubility Products: K_so^*=[Fe³⁺][H⁺]^-2.86

Authors

Robert H. Byrne, University of South FloridaFollow
Yu-Ran Luo, University of South Florida

Document Type

Article

Publication Date

2000

Digital Object Identifier (DOI)

https://doi.org/10.1016/S0016-7037(00)00329-X

Abstract

Previous studies have indicated that hydrous ferric oxide precipitates, formed and aged at low temperatures, exhibit solubility products of the form K^∗_S0 = [Fe³⁺][H⁺]^−m, where m < 3 ([ ]  free ion concentration). Although previous observations have either been obtained over a very narrow pH range or have involved phase separations and solution chemical modeling, the present work involves direct potentiometric observations of log [Fe³⁺] and log [H⁺] over a wide range of Fe³⁺ concentrations and pH. Our observations obtained at 25°C in 0.7 molar NaClO₄ provide substantial evidence for log [Fe³⁺] vs. pH relationships with slopes (m) smaller than three but larger than those obtained in previous works (m = 2.70 and m = 2.35). Over a four unit range in pH and a nearly 12 order of magnitude range in [Fe³⁺] the observed relationship between pH and log [Fe³⁺] in this work is log [Fe³⁺] = 4.28 ± 0.05 − (2.86 ± 0.009) pH. This solubility behavior has substantial implications for the behavior of Fe^III in natural waters.

Was this content written or created while at USF?

Yes

Citation / Publisher Attribution

Geochimica et Cosmochimica Acta, v. 64, issue 11, p. 1873-1877

Scholar Commons Citation

Byrne, Robert H. and Luo, Yu-Ran, "Direct Observations of Nonintegral Hydrous Ferric Oxide Solubility Products: K_so^*=[Fe³⁺][H⁺]^-2.86" (2000). Marine Science Faculty Publications. 1726.
https://digitalcommons.usf.edu/msc_facpub/1726