HR: 1340h
AN: H33A-0456    [Abstracts]
TI: Use of 3D X-ray Microtomography to Observe the Structure of Colloidal Zirconia Deposits in Sand Columns
AU: Stone, S H
EM: s-stone2@northwestern.edu
AF: Northwestern University, Dept. of Civil and Environmental Engineering 2145 Sheridan Rd., Evanston, IL 60208 United States
AU: Chen, C
EM: c-chen11@northwestern.edu
AF: Northwestern University, Dept. of Civil and Environmental Engineering 2145 Sheridan Rd., Evanston, IL 60208 United States
AU: Keane, D T
EM: dtkeane@northwestern.edu
AF: DND-CAT Synchrotron Research Center, Advanced Photon Source, 9700 S. Cass Ave., Argonne, IL 60439-4857 United States
AU: * Packman, A I
EM: a-packman@northwestern.edu
AF: Northwestern University, Dept. of Civil and Environmental Engineering 2145 Sheridan Rd., Evanston, IL 60208 United States
AB: We are utilizing the tomography capability of the DuPont-Northwestern-Dow Collaborative Access Team (DND-CAT) at the Advanced Photon Source (APS), Argonne National Laboratory for studies of in situ sediment structure. Images of a sediment sample are taken at a number of different angles as the incident x-ray beam passes through it, and a three-dimensional view of the interior of the sample is then reconstructed from these maps using computed tomography. These images allow examination of individual sediment grains and the pore structure with a spatial resolution of as little as a few microns. In addition, the distribution of a particular element can be determined by difference tomography, i.e., by obtaining a series of images both above and below the x-ray absorption edge of the element of interest and then subtracting the resulting tomographic reconstructions. We used this approach to resolve the distribution of deposited zirconia particles in a matrix of silica sand. Zirconia particles were deposited in small sand columns under steady upflow conditions, and the columns were rinsed by several pore volumes of particle-free water. The saturated columns were then sealed, removed from the upflow system, and transported to the APS for analysis. Column experiments were conducted with a range of influent zirconia concentrations and background solution conditions. We will present three-dimensional tomographic reconstructions showing the structure of both the porous medium and the zirconia particle deposits, along with results on the bulk deposition of zirconia.
DE: 4809 Colloids
DE: 1815 Erosion and sedimentation
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting