Effects of natural organic matter properties on the dissolution kinetics of zinc oxide nanoparticles

Environmental Science & Technology
By: , and 

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Abstract

The dissolution of zinc oxide (ZnO) nanoparticles (NPs) is a key step of controlling their environmental fate, bioavailability, and toxicity. Rates of dissolution often depend upon factors such as interactions of NPs with natural organic matter (NOM). We examined the effects of 16 different NOM isolates on the dissolution kinetics of ZnO NPs in buffered potassium chloride solution using anodic stripping voltammetry to directly measure dissolved zinc concentrations. The observed dissolution rate constants (kobs) and dissolved zinc concentrations at equilibrium increased linearly with NOM concentration (from 0 to 40 mg C L–1) for Suwannee River humic and fulvic acids and Pony Lake fulvic acid. When dissolution rates were compared for the 16 NOM isolates, kobs was positively correlated with certain properties of NOM, including specific ultraviolet absorbance (SUVA), aromatic and carbonyl carbon contents, and molecular weight. Dissolution rate constants were negatively correlated to hydrogen/carbon ratio and aliphatic carbon content. The observed correlations indicate that aromatic carbon content is a key factor in determining the rate of NOM-promoted dissolution of ZnO NPs. The findings of this study facilitate a better understanding of the fate of ZnO NPs in organic-rich aquatic environments and highlight SUVA as a facile and useful indicator of NOM interactions with metal-based nanoparticles.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effects of natural organic matter properties on the dissolution kinetics of zinc oxide nanoparticles
Series title Environmental Science & Technology
DOI 10.1021/acs.est.5b02406
Volume 49
Issue 19
Year Published 2015
Language English
Publisher ACS
Contributing office(s) Toxic Substances Hydrology Program, National Research Program - Central Branch
Description 9 p.
First page 11476
Last page 11484