In the context of groundwater remediation, an increasing interest was found towards nanoscale and microscale zero-valent iron particles (NZVI and MZVI, respectively). Critical points for successfully full-scale applications are stability against aggregation and sedimentation, mobility in subsurface environments, and longevity in the subsurface. Iron particles should remain in suspension for a time sufficient for slurry preparation, handling and injection in the subsurface. Also, they should have a sufficient mobility in the subsurface to be transported for some extent around the injection point. However, several studies have shown MZVI and NZVI to be scarcely mobile and stable in both laboratory studies and field-scale tests, due to fast sedimentation (MZVI) or aggregation and subsequent sedimentation (NZVI). Coating of the iron nanoparticles with hydrophilic polymers and increasing the viscosity of the MZVI and NZVI slurry were found successful approaches for improving both colloidal stability and mobility in lab-scale experiments. In particular polymeric shear thinning solutions were found effective in enhancing stability of the iron dispersion when the product is stored (as high viscosity prevent gravitational settling and aggregation of the particles) without hindering the injection. In this work the mechanisms controlling the transport of colloidal suspensions in saturated porous media, the improvement of stability of highly concentrated micro- and nanosized iron suspensions, and the assessment of their transportability via addiction of “green” polymers are studied. Laboratory transport tests in one-dimensional columns are reported, exploring the effects of both flow rate and polymer concentration on particles mobility. A numerical model is also presented that describes the transport of highly concentrated suspensions of iron particles, in particular during their injection in the subsurface, and in the early stages of migration through the porous matrix, namely E-MNM1D. Numerical modelling of transport processes of iron particles transport in porous media, is necessary for the interpretation of laboratory tests, and for the simulation of injection at the field scale.

Injection of microscale zero-valent iron slurries for aquifer remediation: laboratory tests and transport modelling / Tosco, TIZIANA ANNA ELISABETTA; Gastone, Francesca; Sethi, Rajandrea. - ELETTRONICO. - (2013). (Intervento presentato al convegno 5th International Conference on Porous Media tenutosi a Prague nel 22-24 May 2013).

Injection of microscale zero-valent iron slurries for aquifer remediation: laboratory tests and transport modelling

TOSCO, TIZIANA ANNA ELISABETTA;GASTONE, FRANCESCA;SETHI, RAJANDREA
2013

Abstract

In the context of groundwater remediation, an increasing interest was found towards nanoscale and microscale zero-valent iron particles (NZVI and MZVI, respectively). Critical points for successfully full-scale applications are stability against aggregation and sedimentation, mobility in subsurface environments, and longevity in the subsurface. Iron particles should remain in suspension for a time sufficient for slurry preparation, handling and injection in the subsurface. Also, they should have a sufficient mobility in the subsurface to be transported for some extent around the injection point. However, several studies have shown MZVI and NZVI to be scarcely mobile and stable in both laboratory studies and field-scale tests, due to fast sedimentation (MZVI) or aggregation and subsequent sedimentation (NZVI). Coating of the iron nanoparticles with hydrophilic polymers and increasing the viscosity of the MZVI and NZVI slurry were found successful approaches for improving both colloidal stability and mobility in lab-scale experiments. In particular polymeric shear thinning solutions were found effective in enhancing stability of the iron dispersion when the product is stored (as high viscosity prevent gravitational settling and aggregation of the particles) without hindering the injection. In this work the mechanisms controlling the transport of colloidal suspensions in saturated porous media, the improvement of stability of highly concentrated micro- and nanosized iron suspensions, and the assessment of their transportability via addiction of “green” polymers are studied. Laboratory transport tests in one-dimensional columns are reported, exploring the effects of both flow rate and polymer concentration on particles mobility. A numerical model is also presented that describes the transport of highly concentrated suspensions of iron particles, in particular during their injection in the subsurface, and in the early stages of migration through the porous matrix, namely E-MNM1D. Numerical modelling of transport processes of iron particles transport in porous media, is necessary for the interpretation of laboratory tests, and for the simulation of injection at the field scale.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2508518
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