Complex Conductivity Response to Silver Nanoparticles in Partially Saturated Sand Columns


The increase in the use of nanoscale materials in consumer products has resulted in a growing concern of their potential hazard to ecosystems and public health from their accidental or intentional introduction to the environment. Key environmental, health, and safety research needs include knowledge and methods for their detection, characterization, fate, and transport. Specifically, techniques available for the direct detection and quantification of their fate and transport in the environment are limited. Their small size, high surface area to volume ratio, interfacial, and electrical properties make metallic nanoparticles, such as silver nanoparticles, good targets for detection using electrical geophysical techniques. Here we measured the complex conductivity response to silver nanoparticles in sand columns under varying moisture conditions (0-30%), nanoparticle concentrations (0-10 mg/g), lithology (presence of clay), pore water salinity (0.0275 and 0.1000 S/m), and particle size (35, 90-210 and 1500-2500 nm). Based on the Cole-Cole relaxation models we obtained the chargeability and the time constant. We demonstrate that complex conductivity can detect silver nanoparticles in porous media with the response enhanced by higher concentrations of silver nanoparticles, moisture content, ionic strength, clay content and particle diameter. Quantification of the volumetric silver nanoparticles content in the porous media can also be obtained from complex conductivity parameters based on the strong power law relationships.


Geosciences and Geological and Petroleum Engineering


United States. Environmental Protection Agency. Office of Research and Development


Partial funding provided by student services contract #EP09D000553 from EPA

Keywords and Phrases

Consumer Products; Ionic Strength; Lithology; Metal Nanoparticles; Moisture; Nanoparticles; Nanostructured Materials; Particle Size; Porous Materials; Public Health; Cole-Cole Relaxation Model; Complex Conductivity; Geophysical Techniques; Metallic Nanoparticles; Nano Silver; Nanoparticle Concentrations; Partially Saturated Sands; Power Law Relationship; Silver; Concentration (composition); Electrical Conductivity; Environmental Fate; Moisture Content; Nanoparticle; Porous Medium; Salinity; Sand; Environmental Nanomaterials; Nanosilver

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Article - Journal

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