A rapid screening technique for estimating nanoparticle transport in porous media

Quantifying the mobility of engineered nanoparticles in hydrologic pathways from point of release to human or ecological receptors is essential for assessing environmental exposures. Column transport experiments are a widely used technique to estimate the transport parameters of engineered nanoparticles in the subsurface environment, but this technique is often time-consuming, labor-intensive, and of low sample throughput. Thus, the traditional column experiment is unlikely to be a viable tool for processing the large numbers of engineered nanomaterials in various types of porous media that will be needed for environmental impact assessment and regulatory activities. Here we present a high throughput screening technique for nanoparticle transport using 96 deep well plate columns packed with porous media. The technique was tested for the transport of 60-nm polystyrene microspheres, fullerene C60 nanoparticles (aq/nC60), and surfactant-wrapped single-walled carbon nanotubes (SWNTs) in 0.001-0.1% sodium dodecyl sulfate (SDS) through Iota quartz sand and Calls Creek sediment. Our results showed that this screening technique produced highly reproducible column hydrodynamic properties as revealed by conservative tracer tests and precise measurements of nanoparticle transport parameters. Additionally, all nanoparticles exhibited greater retention in the sediment than in Iota quartz, and the retention of SDS-SWNTs decreased with increasing SDS concentrations, which is consistent with the existing literature. We conclude that this technique is well suited for rapidly screening the mobility of engineered nanomaterials in porous media.