Neutron tomography of porous aluminum electrodes used in electrocoagulation of groundwater

G. G. Jang, Y. Zhang, J. K. Keum, Y. Z. Bootwala, M. C. Hatzell, D. Jassby, C. Tsouris

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

In this work, neutron computed tomography (CT) is employed to investigate the dissolution of porous aluminum electrodes during electrocoagulation (EC). Porous electrodes were chosen in efforts to reduce electric power requirements by using larger surface-area electrodes, having both inner and outer surface, for the EC process. Neutron CT allowed 3D reconstruction of the porous electrodes, and image analysis provided the volume of each electrode vs. thickness, which can indicate whether the inner surface is effectively involved in EC reactions. For the anode, the volume decreased uniformly throughout the thickness of the electrode, indicating that both the outer and inner surface participated in electrochemical dissolution, while the volume of the cathode increased uniformly vs. thickness, indicating deposition of material on both the outer and inner surface. The attenuation coefficient vs. thickness, increased for both anode and cathode, indicating surface chemistry changes. For the anode, the attenuation coefficient increased slightly but uniformly, probably due to aluminum oxide formation on the surface of the anode. For the cathode, the attenuation coefficient increased more than for the anode and nonuniformly. The higher increase in the attenuation coefficient for the cathode is due to precipitation of aluminum hydroxide on the electrode surface, which added hydrogen. Image analysis also showed that, although the attenuation coefficient increased throughout the thickness of the electrode, most of the hydroxide deposition occurred on the outer surface. Energy analysis showed that porous electrodes can be used to reduce process energy requirements by as much as 4 times compared to solid electrodes.

Original languageEnglish
Article number1046627
JournalFrontiers in Chemical Engineering
Volume4
DOIs
StatePublished - 2022

Funding

This work was supported by the National Alliance for Water Innovation (NAWI), through funding from the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office, under Funding Opportunity Announcement DE-FOA-0001905. The authors are grateful to Erik Stringfellow for instrument support, and Qiu Zhang for chemistry laboratory support at the ORNL neutron facility. The research was conducted at Oak Ridge National Laboratory (ORNL), which is managed by UT Battelle, LLC, for the US Department of Energy (DOE) under contract DE-AC05-00OR22725. Neutron tomography and materials characterization (SEM) used resources at the High Flux Isotope Reactor and the Center for Nanophase Materials Sciences, all of which are DOE office of Science User Facility operated by Oak Ridge National Laboratory.

Keywords

  • electrocoagulation
  • groundwater treatment
  • neutron imaging
  • neutron tomography
  • porous aluminum electrodes

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