Transport of stabilized iron nanoparticles in porous media: Effects of surface and solution chemistry and role of adsorption

Additional Info

  • Practice Areas: Contaminated Sites
  • Event or Publication: Publication
  • Title: Journal of Hazardous Materials
  • All Authors: Man Zhang, Feng Hec, Dongye Zhaoa, Xiaodi Haod
  • Geosyntec Authors: Man Zhang
  • Citation: Volume 322, Part A, 15 January 2017, Pages 284–291
  • Date: 2017
  • Type: Publication (Journal)

Carboxymethyl cellulose (CMC) stabilized zero-valent iron (ZVI) (CMC-ZVI) nanoparticles have been extensively tested for remediation of soil and groundwater. This study investigated effects of iron oxide and aluminum oxide on retention and transport of CMC-ZVI nanoparticles, which have a mean hydrodynamic diameter of 155nm.

Column breakthrough experiments showed that the metal oxides coatings on quartz sand greatly enhanced particle retention. A mechanistically sounder transport model was proposed by incorporating a Langmuir-type adsorption rate law into the classic convection–dispersion equation with the adsorption parameters derived from independent experiments. The model allows for a quantitative evaluation of the role of adsorption. While filtration is the primary mechanism for particle retention at lower pore velocities, adsorption becomes more significant at elevated velocities. The presence of 40–80 mg-C L−1 of natural organic matter and high ionic strength (up to 200 mM CaCl2) had negligible effect on the breakthrough profiles of the nanoparticles. Starch, a neutral polysugar stabilizer, was also tested as a stabilizer. Starch-stabilized ZVI nanoparticles, with a mean hydrodynamic diameter of 303 nm, displayed a higher particle retention than CMC-ZVI. The information and modeling approach can facilitate our understanding of fate and transport of stabilized ZVI nanoparticles under various geochemical conditions.

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