Effect of Particle Diameter on Silver Nanoparticle Aggregation and Dissolution in Aquatic Systems
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Date
2017-05
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The Ohio State University
Abstract
Silver nanoparticles (AgNPs) are used in many consumer products as an antibacterial agent. The small size of these particles means they are more reactive, because their surface area is larger. However, the widespread usage of AgNPs has consequently led to their release into the aquatic environment, where they have the potential to harm organisms that are not their intended target. Studies have been conducted on the fate and toxicity of AgNPs, but each study uses different sizes, calling into question the consistency of results across different sizes of AgNPs. In addition, a variety of sizes may be utilized in consumer products. One method of determining the behavior of AgNPs in the environment uses the addition of electrolytes to determine their effect on the dissolution and/or aggregation of AgNPs. This research focused on the effect of different concentrations of three different electrolytes (NaNO3, CaCl2 and NaCl) on the aggregation kinetics of three different sizes of citrate-coated silver nanoparticles (20 nm, 50 nm, 80 nm). It was hypothesized that AgNPs with a smaller initial particle size would be less stable than AgNPs with a larger initial particle size in the presence of electrolytes. After the addition of an electrolyte to a silver nanoparticle suspension, the change in size of the particles was measured over time (4 – 15 minutes) using Dynamic Light Scattering. Silver nanoparticles of all three sizes were found to be equally stable in NaNO3 and NaCl, and larger particles were more stable in CaCl2. These results suggest that further investigation into the effect of AgNP size on aggregation may be necessary.
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Keywords
silver nanoparticles, kinetics, aggregation, CCC, size-dependent, DLVO-theory