Chromium(III) substitution inhibits the Fe(II)-accelerated transformation of schwertmannite.

ABSTRACT: Schwertmannite is an Fe(III)-oxyhydroxysulfate which is common in acid mine drainage (AMD) and acid sulfate soil (ASS) environments. Natural schwertmannite is often enriched in Cr(III), yet the effects of Cr(III) substitution on schwertmannite transformation to more stable Fe(III) minerals has not been addressed. Here we examine, for the first time, the effects of Cr(III) substitution on the Fe(II)-accelerated transformation of schwertmannite. X-ray diffraction (XRD) and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy shows that Cr(III) substitution inhibits schwertmannite transformation. Substitution at a Cr(III):Fe(III) ratio of 0.025 decreased schwertmannite transformation (at pH 6.5) by 18-49% (depending on Fe(II) concentrations) relative to that of Cr(III)-free

SUBMITTER: Choppala G 

PROVIDER: S-EPMC6281269 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature