Two Dimensional Transport Characteristics of Surface Stabilized Zero-valent Iron Nanoparticles in Porous Media

Abstract

Zero-valent iron nanoparticles (INP) were synthesized and stabilized using poly acrylic acid (PAA) to yield stabilized INP (S-INP). A two-dimensional physical model was used to study the fate and transport of the INP and S-INP in porous media under saturated, steady-state flow conditions. Transport data for a nonreactive tracer, INP, and S-INP were collected under similar flow conditions. The results show that unstabilized INP cannot be transported into groundwater systems. On the other hand, the S-INP can be transported like a tracer without significant retardation. However, the S-INP plume migrated downward as it moved horizontally in the physical model, indicating that small density gradients have significant influence on two-dimensional transport. The variable-density groundwater flow model SEAWAT was used to model the observed density-driven transport patterns. This is the first time a two-dimensional transport data set is reported for demonstrating the multidimensional transport characteristics of nanoparticles. The data shows the importance of density effects, which cannot be fully discerned using one-dimensional, column experiments. Finally, we also demonstrate that the numerical model SEAWAT can be used to predict the density-driven transport characteristics of S-INP in groundwater aquifers.

Numerical prediction of diffusion and electric field-induced iron nanoparticle transport

“…The polyacrylic acid coated iron nanoparticles (PAA-nZVI) suspensions were freshly prepared before each experiment, according to the method used by Kanel et al [18] and had a concentration of 4 g L -1 of nZVI.…”

“…With the development of advanced nanotechnologies since late nineties, due to their size and reactivity that allowed an easy injection,zero valent iron nanoparticles (nZVI) were considered a promising step forward in soil and groundwater clean-up, particularly targeting organochlorines [4][5][6][7][8]. The nZVI transport in porous media was studied in column tests with sand [9][10][11][12][13][14][15][16], glass beads [17][18][19] and model soils [20,21]. These studies showed that nZVI has a tendency to aggregate quickly and settle in the pores, primarily due to magnetic attractive forces [22].…”

Characterization of preferential flow paths between boreholes in fractured rock using a nanoscale zero-valent iron tracer test

“…9 The acoustic televiewer log, profile of the section transmissivity, and profile of the weight of iron nanoparticles attracted to the magnet in the observation well C that most of the injected nZVI slurry in well A did not migrate to well C. This phenomenon is possibly attributed to the dominance of downward migration of nZVI slurry in well A due to the gravity effect (Kanel et al 2008), as observed during the laboratory test. Only a small amount would follow the hydraulic gradient to migrate laterally through the permeable fracture.…”

Dynamic and equilibrium studies of the RDX removal from soil using CMC-coated zerovalent iron nanoparticles

“…The major problem rarely addressed in the column studies is the aggregation of iron nanoparticles making their transport through soil ineffective and their chemical reactivity slower (He et al, 2007;Kanel et al, 2008). Extensive studies have been devoted to the stabilization of the ZVINs in batch studies.…”