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Kinetics and Mechanisms of Cr6+ Reduction by Structural Fe(II) in Clay Minerals

Glasser, Paul Allen

Abstract Details

2014, Master of Science, Miami University, Geology and Environmental Earth Science.
Hexavalent chromium (Cr6+) is a toxic environmental contaminant. Microbial bioreduction of structural Fe(III) in clay minerals and subsequent reaction with Cr6+ is a sustainable remediation method. Clay minerals naturally undergo multiple redox cycles, which may affect reactivity towards Cr6+ reduction. The kinetics and reactivity of this reaction are poorly understood. The objective of this study was to understand the kinetics and mechanisms of Cr6+ reduction by clay mineral structural Fe(II). A suite of Fe(III)-bearing clay minerals were bioreduced and re-oxidized four times. In each cycle, bioreduced clay mineral reactivity and kinetics towards Cr6+ reduction was tested. Generally with increased redox cycling, rate and extent of Fe(III) bioreduction decreased, whereas with Cr6+ it increased, especially with temperature. Reaction products were analyzed for changes in physicochemical properties, mineralogy, and morphology by spectroscopy and microscopy. Redox cycling induced permanent changes in surface area, but little mineralogical change, suggesting clay minerals largely remained in solid state. Reduced Cr(III) phases occurred in the form of Cr-Fe-hydroxides. This study has implications for understanding clay-metal redox chemistry and Cr6+ remediation at contaminated sites.
Hailiang Dong, PhD (Advisor)
Mark Krekeler, PhD (Committee Member)
Jonathan Levy, PhD (Committee Member)
76 p.

Recommended Citations

Citations

  • Glasser, P. A. (2014). Kinetics and Mechanisms of Cr6+ Reduction by Structural Fe(II) in Clay Minerals [Master's thesis, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1389010915

    APA Style (7th edition)

  • Glasser, Paul. Kinetics and Mechanisms of Cr6+ Reduction by Structural Fe(II) in Clay Minerals. 2014. Miami University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1389010915.

    MLA Style (8th edition)

  • Glasser, Paul. "Kinetics and Mechanisms of Cr6+ Reduction by Structural Fe(II) in Clay Minerals." Master's thesis, Miami University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1389010915

    Chicago Manual of Style (17th edition)