Abstract
Nitroaromatic compounds are groundwater pollutants that can be degraded through reactions with Fe(II) adsorbed on iron oxide nanoparticles, although little is known about the evolving reactivity of the minerals with continuous pollutant exposure. In this work, Fe(II)/goethite reactivity toward 4-chloronitrobenzene (4-ClNB) as a function of pH, organic matter presence, and reactant concentrations was explored using sequential-spike batch reactors. Reaction rate constants were smaller with lower pH, introduction of organic matter, and diluted reactant concentrations as compared to a reference condition. Reaction rate constants did not change with the number of 4-ClNB spikes for all reaction conditions. Under all conditions, oxidative goethite growth was demonstrated through X-ray diffraction, magnetic characterization, and transmission electron microscopy. Nonparametric statistics were applied to compare histograms of lengths and widths of goethite nanoparticles as a function of varied solution conditions. The conditions that slowed the reaction also resulted in statistically shorter and wider particles than for the faster reactions. Additionally, added organic matter interfered with particle growth on the favorable {021} faces to a greater extent, with statistically reduced rate of growth on the tip facets and increased rate of growth on the side facets. These data demonstrate that oxidative growth of goethite in aqueous systems is dependent on major groundwater variables, such as pH and the presence of organic matter, which could lead to the evolving reactivity of goethite particles in natural environments.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 10406-10412 |
| Number of pages | 7 |
| Journal | Environmental Science and Technology |
| Volume | 50 |
| Issue number | 19 |
| DOIs | |
| State | Published - Oct 4 2016 |
Bibliographical note
Funding Information:This work was supported by National Science Foundation grant ECS-1012193 (R.L.P. and W.A.A.) and the Graduate School Doctoral Dissertation Fellowship at the University of Minnesota (J.H.S.). Magnetic characterization was performed at the Institute for Rock Magnetism (IRM) at the University of Minnesota with assistance from Becky E. Strauss. The IRM is a US National Multiuser Facility supported through the Instrumentation and Facilities program of the National Science Foundation, Earth Sciences Division, and by funding from 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:
© 2016 American Chemical Society.