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Tangential Flow Ultrafiltration: A “Green” Method for the Size Selection and Concentration of Colloidal Silver Nanoparticles
Published on: October 4, 2012
Size-controlled dissolution of organic-coated silver nanoparticles
Rui Ma1, Clément Levard, Stella M Marinakos
1Center for the Environmental Implications of NanoTechnology (CEINT), Duke University, Durham, North Carolina 27708, USA.
Environmental Science & Technology
|December 7, 2011
Summary
Silver nanoparticle (Ag NP) solubility is primarily determined by particle size, not synthesis method or coating. This finding allows for predicting Ag NP environmental behavior using the modified Kelvin equation based on size.
Area of Science:
- Environmental Science
- Materials Science
- Nanotechnology
Background:
- Silver nanoparticles (Ag NPs) are widely used, but their environmental solubility, toxicity, and persistence are not fully understood.
- Solubility is a key factor influencing the behavior and impact of nanomaterials in various environments.
Purpose of the Study:
- To investigate the solubility of organic-coated Ag NPs across a range of sizes (5-80 nm).
- To determine the influence of synthesis methods and organic coatings on Ag NP solubility.
- To correlate Ag NP solubility with particle size and structural properties.
Main Methods:
- Characterization of Ag NP size and morphology using transmission electron microscopy (TEM).
- Determination of local silver structure and crystal lattice parameters via X-ray absorption fine structure (XAFS) spectroscopy.
- Synchrotron-based X-ray scattering and pair distribution function (PDF) analysis to evaluate NP structure.
- Measurement of Ag NP solubility in a bicarbonate solution at pH 8.
Main Results:
- Ag NP solubility showed a strong correlation with particle size, as predicted by the modified Kelvin equation.
- Particle size was a more significant factor in solubility than synthesis method or organic coating.
- Surface tension of Ag NPs was estimated at ~1 J/m², consistent with bulk silver.
- Analysis confirmed no significant lattice strain in Ag NPs down to 6 nm.
Conclusions:
- Ag NP solubility is predominantly governed by particle size.
- The modified Kelvin equation accurately estimates Ag NP solubility for particles in the 5-40 nm range.
- Understanding size-dependent solubility is crucial for predicting Ag NP environmental fate and risk.
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