Technical ArticleINFLUENCE OF IRON OXIDE FORMING CONDITIONS ON PYRITE OXIDATIONZhang, Y. L.; Evangelou, V. P.Author Information Department of Agronomy, Univ. of Kentucky, Lexington, KY 40546-0091. Contribution from the Dep. of Agronomy, Univ. of Kentucky Agric. Exp. Stn. The investigation reported in this paper is in connection with a project of the Kentucky Agric. Exp. Stn. and is published with the approval of the director. Address correspondence to V. P. Evangelou, Department of Agronomy, N-122 Ag. Sci. Center North, University of Kentucky, Lexington, KY 40546-0091. E-mail:[email protected] Received Feb. 2, 1996; accepted Aug. 15, 1996. Soil Science: December 1996 - Volume 161 - Issue 12 - p 852-864 Buy Abstract Iron released from pyrite during oxidation in slightly acid to alkaline conditions is known to produce one or more forms of iron oxide. There is, however, no solid understanding of how, and to what degree, these iron oxides affect pyrite oxidation. This was investigated by leaching pyrite in a chromatographic column with a 1-cm i.d. and a flow rate of 0.43 mL min-1 at room temperature with a solution containing hydrogen peroxide (H2O2) buffered with acetate. When the leaching solution reached pyrite surfaces, H2O2 oxidized a small portion of pyrite and released Fe3+. The latter hydrolyzed to form an amorphous ferric oxyhydroxide that precipitated as a passive coating on the pyritic surfaces. The rate of pyrite oxidation was shown to be suppressed greatly by these coatings. This suppressive effect was attributed first to the coating's ability to serve as a sink for Fe3+, thus making it no longer available to oxidize pyrite, and second to the coating's ability to act as a barrier to the upcoming H2O2, thereby physically protecting the pyritic surfaces. It was also shown that the above leaching solution acted as a coating agent when buffered at pH 4.0 to 6.0. Values higher than pH 6 were not investigated. © Williams & Wilkins 1996. All Rights Reserved.