The use of Micro- and Nano-scale Zerovalent Iron (MZVI and NZVI, respectively) particles represents a promising technology for the remediation of aquifer systems contaminated by a wide variety of pollutants. ZVI particles can be injected in the aquifer systems even at high depths below ground surface. The application of this technology is limited by reduced suspensions stability and filtration in the porous media due to the fast sedimentation (MZVI) of the iron and to the particles aggregation (NZVI). To enhance stability and mobility of the suspensions it is fundamental to use stabilizing agents which increase the solution viscosity, thus reducing sedimentation and aggregation rates. Some biological hydrocolloids have been demonstrated very effective due to their non Newtonian, shear thinning, behaviour. In this work, performed in the framework of the AQUAREHAB project (FP7 - G. A. Nr. 226565), the use of guar gum (GG) is presented. GG is an hydrocolloid with shear-thinning behaviour that can be easily biodegraded using enzymes in order to recover the reactivity of the iron after injection. For the correct dimensioning of a field application a full rheological characterization of the guar gum solution at variable concentration has to be carried out. For this purpose several colloidal suspensions preparations at different polymer concentrations, with and without iron particles, have been tested and functional relationships have been derived. The evaluation of the apparent viscosity in the porous medium is of pivotal importance for the prediction of the injection pressure. Filtration tests performed in a 1D sand packed column demonstrated that this parameter can be deduced from rheological tests, measuring shear viscosity. Moreover to reduce pressure injection and increase iron particles mobility, stability tests were performed, which allowed to define an enhanced protocol for the preparation of the suspensions.

Rheology and optimized preparation of guar gum solutions for the suspension of zerovalent iron particles / Gastone, Francesca; Tosco, TIZIANA ANNA ELISABETTA; Sethi, Rajandrea. - ELETTRONICO. - (2013), pp. 85-90. (Intervento presentato al convegno 2nd European Symposium on Water Technology and Management tenutosi a Leuven nel 20-21 November 2013).

Rheology and optimized preparation of guar gum solutions for the suspension of zerovalent iron particles

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

Abstract

The use of Micro- and Nano-scale Zerovalent Iron (MZVI and NZVI, respectively) particles represents a promising technology for the remediation of aquifer systems contaminated by a wide variety of pollutants. ZVI particles can be injected in the aquifer systems even at high depths below ground surface. The application of this technology is limited by reduced suspensions stability and filtration in the porous media due to the fast sedimentation (MZVI) of the iron and to the particles aggregation (NZVI). To enhance stability and mobility of the suspensions it is fundamental to use stabilizing agents which increase the solution viscosity, thus reducing sedimentation and aggregation rates. Some biological hydrocolloids have been demonstrated very effective due to their non Newtonian, shear thinning, behaviour. In this work, performed in the framework of the AQUAREHAB project (FP7 - G. A. Nr. 226565), the use of guar gum (GG) is presented. GG is an hydrocolloid with shear-thinning behaviour that can be easily biodegraded using enzymes in order to recover the reactivity of the iron after injection. For the correct dimensioning of a field application a full rheological characterization of the guar gum solution at variable concentration has to be carried out. For this purpose several colloidal suspensions preparations at different polymer concentrations, with and without iron particles, have been tested and functional relationships have been derived. The evaluation of the apparent viscosity in the porous medium is of pivotal importance for the prediction of the injection pressure. Filtration tests performed in a 1D sand packed column demonstrated that this parameter can be deduced from rheological tests, measuring shear viscosity. Moreover to reduce pressure injection and increase iron particles mobility, stability tests were performed, which allowed to define an enhanced protocol for the preparation of the suspensions.
2013
9789058570109
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2526312
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