Size-dependent reactivity of magnetite nanoparticles: a field-laboratory comparison

Environmental Science & Technology
By: , and 

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Abstract

Logistic challenges make direct comparisons between laboratory- and field-based investigations into the size-dependent reactivity of nanomaterials difficult. This investigation sought to compare the size-dependent reactivity of nanoparticles in a field setting to a laboratory analog using the specific example of magnetite dissolution. Synthetic magnetite nanoparticles of three size intervals, ∼6 nm, ∼44 nm, and ∼90 nm were emplaced in the subsurface of the USGS research site at the Norman Landfill for up to 30 days using custom-made subsurface nanoparticle holders. Laboratory analog dissolution experiments were conducted using synthetic groundwater. Reaction products were analyzed via TEM and SEM and compared to initial particle characterizations. Field results indicated that an organic coating developed on the particle surfaces largely inhibiting reactivity. Limited dissolution occurred, with the amount of dissolution decreasing as particle size decreased. Conversely, the laboratory analogs without organics revealed greater dissolution of the smaller particles. These results showed that the presence of dissolved organics led to a nearly complete reversal in the size-dependent reactivity trends displayed between the field and laboratory experiments indicating that size-dependent trends observed in laboratory investigations may not be relevant in organic-rich natural systems.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Size-dependent reactivity of magnetite nanoparticles: a field-laboratory comparison
Series title Environmental Science & Technology
DOI 10.1021/es500172p
Volume 48
Issue 19
Year Published 2014
Language English
Publisher American Chemical Society
Contributing office(s) National Research Program, Toxic Substances Hydrology Program
Description 8 p.
First page 11413
Last page 11420