Enhanced transport of zerovalent iron nanoparticles in saturated porous media by guar gum |
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Authors: | Alberto Tiraferri Rajandrea Sethi |
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Institution: | (1) DITAG – Dipartimento di Ingegneria del Territorio, dell’Ambiente e delle Geotecnologie, Politecnico di Torino, Corso Duca degli Abruzzi, 24, 10129 Torino, Italy |
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Abstract: | In order to ensure adequate mobility of zerovalent iron nanoparticles in natural aquifers, the use of a stabilizing agent
is necessary. Polymers adsorbed on the nanoparticle surface will give rise to electrosteric stabilization and will decrease
attachment to the surface soil grains. Water saturated sand-packed columns were used in this study to investigate the transport
of iron nanoparticle suspensions, bare or modified with the green polymer guar gum. The suspensions were prepared at 154 mg/L
particle concentration and 0.5 g/L polymer concentration. Transport experiments were conducted by varying the ionic strength,
ionic composition, and approach velocity of the fluid. Nanoparticle deposition rates, attachment efficiencies, and travel
distances were subsequently calculated based on the classical particle filtration theory. It was found that bare iron nanoparticles
are basically immobile in sandy porous media. In contrast, guar gum is able to ensure significant nanoparticle transport at
the tested conditions, regardless of the chemistry of the solution. Attachment efficiency values for guar gum-coated nanoparticles
under the various conditions tested were smaller than 0.066. Although the calculated travel distances may not prove satisfactory
for field application, the investigation attested the promising role of guar gum to ensure mobility of iron nanoparticles
in the subsurface environment. |
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Keywords: | Zerovalent iron nanoparticles Guar gum Colloid transport Groundwater remediation Saturated porous media Steric stabilization Environment EHS |
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