Environmental fate of Nanoparticles

The applications of titanium dioxide (TiO₂) nanoparticles (NPs) currently include pigments, photocatalysts, sunscreens, and semi-conductors. Because of these numerous applications, it is likely that they will leak into the environment. Several factors, including aggregation, can affect the fate and toxicity of NPs once in the environment. Aggregation studies of bare TiO₂ NPs have been extensively studied; however, studies concentrating on NPs with different coatings have, for the most part, been unexplored. Functionalization type may affect aggregation. Size and electrophoretic mobility measurements of citrate and click-functionalized titanium dioxide nanoparticles (NPs) were obtained by using a dynamic light scattering technique with a Zetasizer Nano-ZS. Measurements were taken after dark and simulated sunlight exposure. This method provides information regarding the aggregation of the particles (eg. aggregation rate, size, zeta potential, etc.). Citrate-functionalized particles aggregated beginning at 6 h sunlight exposure, but did not aggregate under dark exposure. The click-functionalized particles, however, began aggregating at 1.5 h sunlight exposure. The aggregation of both the citrate and click-functionalized particles after sunlight exposure is hypothesized to be due to light degradation.