Environ. Sci. Technol. 1998, 32, 2839-2845
Surface Oxidation of Pyrite as a Function of pH PASCALE BONNISSEL-GISSINGER,† MARC ALNOT,† JEAN-JACQUES EHRHARDT,† AND P H I L I P P E B E H R A * ,‡ Laboratoire de Chimie Physique pour l'Environnement, UMR 7564 CNRSsUniversite´ Henri Poincare´, 405 rue de Vandœuvre, F 54600 Villers-le`s-Nancy, France, and Institut de Me´canique des Fluides, UMR 7507 Universite´ Louis Pasteurs CNRS, 2 rue Boussingault, F 67000 Strasbourg, France
Pyrite, the most abundant metal sulfide at the surface of Earth, plays a key role in many processes such as acid mine drainage, redox cycling of metals at oxic-anoxic boundaries of lake bottom, and degradation of pollutants. The oxidation of pyrite was studied in batch experiments over a large range of pH (2.5-12), with trace oxygen. Surface analysis of the samples was performed using X-ray photoelectron spectroscopy (XPS). Speciation of the aqueous species was investigated by inductively coupled plasma atomic emission spectrometry (ICP-AES), ionic chromatography, and UV-vis spectrophotometry. The pyrite surface can drastically change with the pH, which was never at steady state and tended to reach an acidic value whatever the initial pH. For pH
