Using chromate to investigate the impact of natural organics on the surface reactivity of nanoparticulate magnetite

Environmental Science & Technology
By: , and 

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Abstract

Chromate was used as a chemical probe to investigate the size-dependent influence of organics on nanoparticle surface reactivity. Magnetite–chromate sorption experiments were conducted with ∼90 and ∼6 nm magnetite nanoparticles in the presence and absence of fulvic acid (FA), natural organic matter (NOM), and isolated landfill leachate (LL). Results indicated that low concentrations (1 mg/L) of organics had no noticeable impact on chromate sorption, whereas concentrations of 50 mg/L or more resulted in decreased amounts of chromate sorption. The adsorption of organics onto the magnetite surfaces interfered equally with the ability of the 6 and 90 nm particles to sorb chromate from solution, despite the greater surface area of the smaller particles. Results indicate the presence of organics did not impact the redox chemistry of the magnetite–chromate system over the duration of the experiments (8 h), nor did the organics interact with the chromate in solution. Brunauer–Emmett–Teller (BET) and scanning electron microscopy (SEM) results indicate that the organics blocked the surface reactivity by occupying surface sites on the particles. The similarity of results with FA and NOM suggests that coverage of the reactive mineral surface is the main factor behind the inhibition of surface reactivity in the presence of organics.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Using chromate to investigate the impact of natural organics on the surface reactivity of nanoparticulate magnetite
Series title Environmental Science & Technology
DOI 10.1021/es504831d
Volume 49
Issue 4
Year Published 2015
Language English
Publisher ACS
Contributing office(s) National Research Program - Eastern Branch, Toxic Substances Hydrology Program
Description 7 p.
First page 2156
Last page 2162