(4v) Evaluating Zero Valent Iron Nanoparticles with Acoustic Resonance Microbalance Techniques

Greenlee, L. F., National Institute of Standards & Technology

Zero valent iron (ZVI) nanoparticles are able to catalyze both oxidation and reduction reactions and therefore are of particular interest for the degradation of organic micropollutants during drinking water treatment. Many organic water contaminants have been recently identified in drinking water sources and in treated wastewater effluent. The persistence and toxicity of these compounds have motivated research in developing novel technologies and strategies to remove the compounds during drinking water and wastewater treatment. Using nanoparticles such as ZVI particles to remove micropollutants takes advantage of the large surface area to volume ratio of the particles and the resulting enhancement of surface properties that increases contaminant adsorption and/or degradation.

This research focuses on the design of bimetallic ZVI nanoparticles for the reduction of halogenated disinfection by-products (DBPs) and the use of acoustic resonance microbalance techniques to analyze the reactivity and lifetime of the particles. Acoustic resonance microbalances have sensitive mass detection and can detect mass changes of nanograms to picograms. A quartz crystal microbalance with dissipation detection (QCM-D) is used to analyze ZVI nanoparticles in real time under different experimental conditions, including water composition, pH, and organic contaminant type. ZVI nanoparticles coated with a secondary transition metal are compared; the catalytic lifetime of the particles is studied as a function of ZVI oxidation. A heated QCM technique (0 ? 400 oC) is developed and used to analyze the extent of organic compound adsorption onto the particles, and thermogravimetric analysis (TGA) (0 ? 900 oC) is used to validate results.