Colloidal suspensions of engineered nanoparticles have been studied in recent years for waste water and in-situ groundwater remediation. Injectable Fe-based materials (nano- and micro-sized zero-valent iron particles, NZVI and MZVI) are an improvement on commonly used granular iron: they can be suspended in a slurry and directly injected into the source of contamination, overcoming most of the limitations of zerovalent iron permeable reactive barriers (PRBs). Moreover, colloidal particles show increased reactivity, thanks to their high specific surface area. To improve colloidal stability and transportability of MZVI and NZVI, the use of highly viscous shear-thinning carrier fluids have been suggested, and proved to be effective. This study, cofunded by European Union project AQUAREHAB (FP7 - Grant Agreement Nr. 226565), presents experimental and modeling results for the transport of highly concentrated (up to 20 g/l) non- Newtonian (namely, shear-thinning) slurries of MZVI and NZVI in sand packed columns. Assessing the mobility of iron-based colloids is a key issue for field applications of these materials. A transport model can provide an estimation of the radius of influence for the injection points, for a correct dimensioning of full scale remediations and to predict short- and long-term mobility of the iron particles injected in the subsurface. If compared to transport models developed for natural colloids and synthetic model particles (namely latex spheres), the model here presented incorporates more complex phenomena. Rheological properties of the shear-thinning carrier fluid, hydrodynamic parameters of the porous medium (porosity, permeability), and colloid concentrations (both suspended and deposed) are strongly inter-dependent, thus resulting in a complex set of coupled partial differential equations and constitutive relationships. The model results highlight that deposition of relevant amounts of iron particles onto the soil grains significantly reduce porosity and permeability, thus resulting in clogging phenomena, especially for nanoscale particles. Moreover, mechanical filtration is shown to play a role under certain hydrochemical conditions, thus influencing the particle transport.

AQUAREHAB – Injection of nanoscale iron suspensions for aquifer remediation: from lab test to field applicatios / Sethi, Rajandrea; Tosco, TIZIANA ANNA ELISABETTA; Comba, Silvia. - STAMPA. - 195:(2010), pp. 61-68. ((Intervento presentato al convegno VEGAS - Kolloquium 2010 tenutosi a Stoccarda nel 7 ottobre 2010.

AQUAREHAB – Injection of nanoscale iron suspensions for aquifer remediation: from lab test to field applicatios

SETHI, RAJANDREA;TOSCO, TIZIANA ANNA ELISABETTA;COMBA, SILVIA
2010

Abstract

Colloidal suspensions of engineered nanoparticles have been studied in recent years for waste water and in-situ groundwater remediation. Injectable Fe-based materials (nano- and micro-sized zero-valent iron particles, NZVI and MZVI) are an improvement on commonly used granular iron: they can be suspended in a slurry and directly injected into the source of contamination, overcoming most of the limitations of zerovalent iron permeable reactive barriers (PRBs). Moreover, colloidal particles show increased reactivity, thanks to their high specific surface area. To improve colloidal stability and transportability of MZVI and NZVI, the use of highly viscous shear-thinning carrier fluids have been suggested, and proved to be effective. This study, cofunded by European Union project AQUAREHAB (FP7 - Grant Agreement Nr. 226565), presents experimental and modeling results for the transport of highly concentrated (up to 20 g/l) non- Newtonian (namely, shear-thinning) slurries of MZVI and NZVI in sand packed columns. Assessing the mobility of iron-based colloids is a key issue for field applications of these materials. A transport model can provide an estimation of the radius of influence for the injection points, for a correct dimensioning of full scale remediations and to predict short- and long-term mobility of the iron particles injected in the subsurface. If compared to transport models developed for natural colloids and synthetic model particles (namely latex spheres), the model here presented incorporates more complex phenomena. Rheological properties of the shear-thinning carrier fluid, hydrodynamic parameters of the porous medium (porosity, permeability), and colloid concentrations (both suspended and deposed) are strongly inter-dependent, thus resulting in a complex set of coupled partial differential equations and constitutive relationships. The model results highlight that deposition of relevant amounts of iron particles onto the soil grains significantly reduce porosity and permeability, thus resulting in clogging phenomena, especially for nanoscale particles. Moreover, mechanical filtration is shown to play a role under certain hydrochemical conditions, thus influencing the particle transport.
9783933761996
File in questo prodotto:
File Dimensione Formato  
2010 Sethi Vegas.pdf

non disponibili

Tipologia: 2. Post-print / Author's Accepted Manuscript
Licenza: Non Pubblico - Accesso privato/ristretto
Dimensione 295.54 kB
Formato Adobe PDF
295.54 kB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2422882
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo