Effect of nonreactive kaolinite on 4-chloronitrobenzene reduction by Fe(ii) in goethite-kaolinite heterogeneous suspensions

Jennifer H. Strehlau, Jonathan D. Schultz, Amanda M. Vindedahl, William A. Arnold, R. Lee Penn

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The kinetics of model contaminant 4-chloronitrobenzene (4-ClNB) reduction by Fe(ii) in aqueous suspensions containing either or both goethite (α-FeOOH) nanoparticles and kaolinite (Al2Si2O5(OH)4) were quantified to elucidate the effects of nonreactive clay minerals on the attenuation of nitroaromatic groundwater contaminants by iron oxide nanoparticles. Increasing the amount of kaolinite in the presence of goethite decreased the reduction rate of 4-ClNB and competitive Fe(ii) adsorption on kaolinite occurred. Cryogenic transmission and scanning electron microscopy (cryo-TEM and cryo-SEM) images did not reveal significant loss of accessible reactive surface area as a result of heteroaggregation. Sequential-spike batch reactors revealed that in the presence of kaolinite, 4-ClNB reduction rate decreased by more than a factor of three with extended reaction as a result of kaolinite dissolution and subsequent incorporation of Al and Si in goethite or on the goethite surface. The reactive sites residing on the {110} faces were comparatively more reactive in the presence of a large loading of kaolinite, resulting in shorter and wider goethite particles after reaction. These results elucidate the mechanisms by which nonreactive clays affect the reactions of Fe(ii)/iron oxides in groundwater systems and indicate that nonreactive clays are not passive components.

Original languageEnglish (US)
Pages (from-to)325-334
Number of pages10
JournalEnvironmental Science: Nano
Volume4
Issue number2
DOIs
StatePublished - 2017

Bibliographical note

Funding Information:
This work was funded by NSF grants ECS-1012193 and CHE-1507496 (R. L. P. and W. A. A.), the Graduate School Doctoral Dissertation Fellowship at the University of Minnesota (J. H. S.), and the Undergraduate Research Opportunity Program (UROP) at the University of Minnesota (J. D. S.). Cryo-SEM was performed with the invaluable assistance of Chris Frethem (Characterization Facility, University of Minnesota). Magnetic characterization was performed at the Institute for Rock Magnetism (IRM) at the University of Minnesota with support from Becky E. Strauss, Joshua M. Feinberg, and Mike Jackson. The IRM is a US National Multi-user Facility supported through the Instrumentation and Facilities program of the National Science Foundation, Earth Sciences Division, and by funding from the University of Minnesota. Analyses by ICP-OES were performed by Rick Knurr with the Analytical Geochemistry Lab, part of the Department of Earth Sciences at the University of Minnesota. Parts of this work were carried out in the Characterization Facility, University of Minnesota, a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org) via the MRSEC program.

Publisher Copyright:
© The Royal Society of Chemistry.

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