The increasing prevalence of nanotechnology in commercial applications and devices carries with it the potential release of engineered nanomaterials into the environment. Subsequently, the stability and mobility of these nanomaterials in soils and groundwaters will determine their ability for long-range transport through the environment and into drinking water supplies. Recently, there has been significant interest in the integration of CdSe nanoparticles and other types of nanocrystals into photovoltaic devices due to their unique nanoscale optical properties. Current demand for the development of alternative energy sources has prompted us to focus on the synthesis of CdSe nanocrystals within a 1-10 nm range and their transfer into aqueous media via a ligand exchange procedure. The stability of CdSe nanoparticles electrostatically stabilized with mercaptoundecanoic acid was investigated through a series of batch experiments over a range of environmentally relevant chemical conditions (particle concentration, pH, ionic strength) by quantifying their kinetic stability, size, morphology, and surface charge. A combination of transmission and scanning electron microscopy, dynamic light scattering, and zeta potential measurements were performed to assess aggregation and surface characteristics of the materials. We found that the continued existence of the CdSe nanoparticles as dispersed colloids rather than aggregates depended strongly on their surface chemistry. The stability (in terms of size) of nanomaterials under environmentally relevant conditions is a critical issue because size significantly influences reactivity and mobility. A combination of batch and column transport experiments will help us to understand the mobility of engineered nanomaterials and their aggregates through saturated and unsaturated porous media, as well as their status after release into the environment.
|Title of host publication||AGU Fall Meeting Abstracts|
|State||Published - 2008|