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. 2013 May 7:28:e2013006.
doi: 10.5620/eht.2013.28.e2013006. Print 2013.

Effects of water chemistry on aggregation and soil adsorption of silver nanoparticles

Sujin Bae  1 , Yu Sik Hwang, Yong-Ju Lee, Sung-Kyu Lee
Affiliations

Effects of water chemistry on aggregation and soil adsorption of silver nanoparticles

Sujin Bae et al. Environ Health Toxicol. .

Abstract

Objectives: In this study, we investigated the influence of ionic strength and natural organic matter (NOM) on aggregation and soil adsorption of citrate-coated silver nanoparticles (AgNPs).

Methods: Time-resolved dynamic light scattering measurements and batch adsorption experiments were used to study their aggregation and soil adsorption behaviors, respectively.

Results: The aggregation rate of AgNPs increased with increasing ionic strength and decreasing NOM concentration. At higher ionic strength, the AgNPs were unstable, and thus tended to be adsorbed to the soil, while increased NOM concentration hindered soil adsorption. To understand the varying behaviors of AgNPs depending on the environmental factors, particle zeta potentials were also measured as a function of ionic strength and NOM concentration. The magnitude of particle zeta potential became more negative with decreasing ionic strength and increasing NOM concentration. These results imply that the aggregation and soil adsorption behavior of AgNPs were mainly controlled by electrical double-layer repulsion consistent with the Derjaguin-Landau-Verwey-Overbeek theory.

Conclusions: This study found that the aggregation and soil adsorption behavior of AgNPs are closely associated with environmental factors such as ionic strength and NOM and suggested that assessing the environmental fate and transport of nanoparticles requires a thorough understanding of particle-particle interaction mechanisms.

Keywords: Aggregation; Ionic strength; Natural organic matter; Silver nanoparticles; Soil adsorption.

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Conflict of interest statement

The authors have no conflicts of interest with material presented in this paper.

Figures

Figure 1
Figure 1
(A) Transmission electron microscopy image, (B) Ultraviolet-visible absorption spectrum of silver nanoparticles.
Figure 2
Figure 2
(A) Representative aggregation profiles, (B) attachment efficiency, and (C) zeta potential of silver nanoparticles at different sodium nitrate (NaNO3) concentrations.
Figure 3
Figure 3
(A) Aggregation profiles and (B) zeta potential of silver nanoparticles in the absence/presence of humic acid under solution conditions of 50 mM sodium nitrate concentration.
Figure 4
Figure 4
(A) The adsorption kinetics of silver nanoparticles (AgNPs) (50 mg/L) on soil at 10 mM sodium nitrate (NaNO3), (B) the adsorption isotherms of AgNPs, and (C) sedimentation percentage of AgNPs in the control test at different NaNO3 concentrations after 48 hours.
Figure 5
Figure 5
(A) The adsorption isotherms of silver nanoparticles (AgNPs) and (B) sedimentation percentage of AgNPs in the control test in the absence/presence of humic acid under solution conditions of 50 mM sodium nitrate (NaNO3) concentration after 48 hours.
See this image and copyright information in PMC

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