HR: 0800h
AN: H51G-0853    [Abstracts]
TI: Effect of Nanoparticle Aggregation, Polydispersity, and Concentration on Transport of Surface- Modified Nanoscale Zerovalent Iron (NZVI) Particles in Saturated Porous Media
AU: * Phenrat, T
EM: tphenrat@andrew.cmu.edu
AF: Civil & Environmental Engineering; Chemical Engineering; Biomedical Engineering; Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, United States
AU: Fagerlund, F
EM: ffagerlu@mines.edu
AF: Center for Experimental Study of Subsurface Environmental Processes at Colorado School of Mines, 1500 Illinois St., Golden, CO 80401, United States
AU: Kim, H
EM: hyejink@andrew.cmu.edu
AF: Civil & Environmental Engineering; Chemical Engineering; Biomedical Engineering; Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, United States
AU: Illangasekare, T
EM: tissa@mines.edu
AF: Center for Experimental Study of Subsurface Environmental Processes at Colorado School of Mines, 1500 Illinois St., Golden, CO 80401, United States
AU: Tilton, R
EM: tilton@andrew.cmu.edu
AF: Civil & Environmental Engineering; Chemical Engineering; Biomedical Engineering; Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, United States
AU: Lowry, G
EM: glowry@cmu.edu
AF: Civil & Environmental Engineering; Chemical Engineering; Biomedical Engineering; Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, United States
AB: Nanoscale zerovalent iron (NZVI) particles for in situ subsurface remediation are typically injected at high particle concentration (1-10 g/L) to minimize costs. At this high particle concentration, aggregation and media ripening effects might limit transportability of the particles. Fundamental understanding of the phenomena controlling the deposition and transport of concentrated surface modified NZVI dispersion is needed for efficient delivery and placement in the contaminant source zone. This study investigates the role of aggregation, particle polydispersity, and particle concentration in transport of poly(styrene sulfonate) (PSS) modified NZVI in saturated sand columns. Bench-scale column experiments are performed at various particle concentrations (0.03 to 6 g/L) at low but environmentally relevant ionic strength, 10 mM Na+, a pore water velocity of 3.2 x 10-4 m/s, and an average collector size of 300 ìm. To elucidate the importance of particle polydispersity, transport and deposition of PSS-modified NZVI with three different particle size distributions are compared. The influence of intrinsically magnetic particle-particle interaction of PSS-modified NZVI on their aggregation and deposition in porous media is assessed by comparing the deposition behavior of PSS-modified NZVI (magnetic) with PSS-modified hematite (nonmagnetic) of the similar surface properties. The transport of PSS70K-modified hematite is not sensitive to particle concentration (from 30 mg/L to 6g/L) or particle polydispersity. In contrast, at high particle concentration (1 to 6 g/L), the transport of PSS70K-modified NZVI (magnetic particles) is sensitive to particle polydispersity, but insensitive to particle concentration. Because the adsorbed layer properties of PSS70K-modified NZVI provide roughly the same particle-collector interaction energies, the difference in deposition behavior of the different NZVI size fractions is attributed to particle-particle interaction (aggregation) which is significantly different between three different size fractions of PSS70K-modified NZVI because magnetic attractive forces increase with r6. This study emphasizes an important role of particle-particle interaction (aggregation) and particle polydispersity in the transport of concentrated NZVI dispersion in porous media.
DE: 1832 Groundwater transport
DE: 4809 Colloids
SC: Hydrology [H]
MN: 2007 Fall Meeting