In the context of groundwater remediation, an increasing interest is related to the use of nanoscale and microscale zero-valent iron particles (NZVI and MZVI, respectively). MZVI and NZVI are not stable when dispersed in water, due to fast aggregation and sedimentation. Consequently, the use of shear thinning solutions of green biopolymers have been recently studied as kinetic stabilizers and viscous carrier fluids for the delivery of MZVI and NZVI. Shear thinning fluids exhibit high viscosity in static conditions, improving the colloidal stability, and lower viscosity at high flow rates enabling the injection at limited pressures. In this work, co-funded by European Union project AQUAREHAB (FP7 - Grant Agreement Nr. 226565), a modeling approach is described to simulate the transport in porous media of nanoscale iron slurries, and implemented in E-MNM1D software (www.polito.it/groundwater/software). Colloid transport mechanisms are controlled by particle-collector and particle-particle interactions, usually modeled using a non equilibrium kinetic model accounting for deposition and release processes. The key aspects included in the E-MNM1D are clogging phenomena (i.e. reduction of porosity and permeability due to particles deposition), and the rheological properties of the carrier fluid (in this project, guar gum solution). The influence of colloid transport on porosity, permeability, and fluid viscosity is explicitly lumped into the model and the shear-thinning nature of the iron slurries is described by a modified Darcy law generalized for non Newtonian fluids. Since during the injection in wells the velocity field is not constant over the distance, E-MNM1D was modified in order to account for variable colloidal transport coefficients on flow rate thus allowing the estimation of the radius of influence during a full scale intervention.
Modeling the injection of Non-Newtonian shear-thinning dispersions of iron particles in porous media / Sethi, Rajandrea; Tosco, TIZIANA ANNA ELISABETTA; Gastone, Francesca. - ELETTRONICO. - (2013). (Intervento presentato al convegno American Geophysical Union (AGU) Fall Meeting 2013 tenutosi a San Francisco nel 9-13 December 2013).
Modeling the injection of Non-Newtonian shear-thinning dispersions of iron particles in porous media
SETHI, RAJANDREA;TOSCO, TIZIANA ANNA ELISABETTA;GASTONE, FRANCESCA
2013
Abstract
In the context of groundwater remediation, an increasing interest is related to the use of nanoscale and microscale zero-valent iron particles (NZVI and MZVI, respectively). MZVI and NZVI are not stable when dispersed in water, due to fast aggregation and sedimentation. Consequently, the use of shear thinning solutions of green biopolymers have been recently studied as kinetic stabilizers and viscous carrier fluids for the delivery of MZVI and NZVI. Shear thinning fluids exhibit high viscosity in static conditions, improving the colloidal stability, and lower viscosity at high flow rates enabling the injection at limited pressures. In this work, co-funded by European Union project AQUAREHAB (FP7 - Grant Agreement Nr. 226565), a modeling approach is described to simulate the transport in porous media of nanoscale iron slurries, and implemented in E-MNM1D software (www.polito.it/groundwater/software). Colloid transport mechanisms are controlled by particle-collector and particle-particle interactions, usually modeled using a non equilibrium kinetic model accounting for deposition and release processes. The key aspects included in the E-MNM1D are clogging phenomena (i.e. reduction of porosity and permeability due to particles deposition), and the rheological properties of the carrier fluid (in this project, guar gum solution). The influence of colloid transport on porosity, permeability, and fluid viscosity is explicitly lumped into the model and the shear-thinning nature of the iron slurries is described by a modified Darcy law generalized for non Newtonian fluids. Since during the injection in wells the velocity field is not constant over the distance, E-MNM1D was modified in order to account for variable colloidal transport coefficients on flow rate thus allowing the estimation of the radius of influence during a full scale intervention.Pubblicazioni consigliate
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https://hdl.handle.net/11583/2526320
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