The Effect of Photolysis on the Stability and Toxicity of Silver Nanoparticles

A.R. Poda, A.J. Kennedy
US Army Corps of Engineers, US

Keywords: silver, photolysis, dissolved organic content

Summary:

The objective of this study was to determine the effect of solar irradiation on the aggregation kinetics and toxicity of a 50 nm silver nanoparticle capped with two different stabilization agents (polyvinylpyrrolidone (PVP) and citrate). The particles were exposed to simulated sunlight by UVA irradiation, and the impact on the irradiation was investigated in solutions with and without 4 mg/L DOC. Field flow fractionation interfaced to inductively coupled plasma mass spectrometry (FFF-ICP-MS, provided a method to determine size and elemental composition of nanoparticles at environmentally relevant concentrations (parts-per-billion). Regardless of the stabilization coating, the standard zooplankton model, Daphnia magna, indicated that the toxicity of nanosilver was significantly reduced when exposed to UV light and was reduced further when exposed to UV light in the presence of DOC (Figure 2). The significance of these findings is that while nanosilver is toxic to aquatic organisms, its toxicity is likely to diminish substantially when subjected to inevitable environmentally relevant mitigating factors.