title: Effects of water chemistry on aggregation and soil adsorption of silver nanoparticles.
abstract: OBJECTIVE
  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.
authors.affiliation: Future Environmental Research Center, Korea Institute of Toxicology, Jinju, Korea.
authors.forename: Sujin
authors.initials: S
authors.lastname: Bae
authors.forename: Yu Sik
authors.initials: YS
authors.lastname: Hwang
authors.forename: Yong-Ju
authors.initials: YJ
authors.lastname: Lee
authors.forename: Sung-Kyu
authors.initials: SK
authors.lastname: Lee
keywords: Aggregation; Ionic strength; Natural organic matter; Silver nanoparticles; Soil adsorption