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  • A systematic evaluation of agglomeration of Ag and TiO2 nanoparticles under freshwater relevant conditions.

A systematic evaluation of agglomeration of Ag and TiO2 nanoparticles under freshwater relevant conditions.

Environmental pollution (Barking, Essex : 1987) (2014-07-08)
Emel Topuz, Laura Sigg, Ilhan Talinli
ABSTRACT

This study aims to investigate effects of freshwater components in order to predict agglomeration behavior of silver nanoparticles coated with citrate (AgNP-Cit), polyvinylpyrrolidone (AgNP-PVP), and of TiO2 nanoparticles. Agglomeration studies were conducted in various media based on combinations of ions, natural organic matter (humic, fulvic acid) and surfactants (sodium dodecyl sulfate, alkyl ethoxylate), at a constant ionic strength of 10 mM over time for up to 1 week. Agglomeration level of AgNP-Cit and TiO2 was mostly dependent on the concentration of Ca(2+) in media, and their size strongly increased to micrometer scale over 1 week. However, AgNP-Cit and TiO2 were stabilized to particle size around 500 nm in the presence of NOM, surfactants and carbonate over 1 week. AgNP-PVP maintained their original size in all media except in the presence of Mg(2+) ions which led to significant agglomeration. Behavior of these engineered nanoparticles was similar in a natural freshwater medium.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Titanium(IV) oxide, nanopowder, 21 nm primary particle size (TEM), ≥99.5% trace metals basis
Sigma-Aldrich
Citric acid, 99%
Sigma-Aldrich
Polyvinylpyrrolidone, average mol wt 10,000
Sigma-Aldrich
Polyvinylpyrrolidone, for molecular biology, nucleic acid hybridization tested, mol wt 360,000
Sigma-Aldrich
Polyvinylpyrrolidone, average mol wt 40,000
Sigma-Aldrich
Citric acid, ACS reagent, ≥99.5%
Sigma-Aldrich
Citric acid, ≥99.5%, FCC, FG
Sigma-Aldrich
Titanium(IV) oxide, anatase, powder, 99.8% trace metals basis
Sigma-Aldrich
Titanium(IV) oxide, anatase, nanopowder, <25 nm particle size, 99.7% trace metals basis
Supelco
Citric acid, Anhydrous, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Titanium(IV) oxide, mixture of rutile and anatase, nanopowder, <100 nm particle size (BET), 99.5% trace metals basis
Supelco
Poly(vinylpolypyrrolidone), ~110 μm particle size
Supelco
Povidone, Pharmaceutical Secondary Standard; Certified Reference Material