Experimental data to demonstrate the density influenced transport characteristics of stabilized iron nanoparticles

Zero valent iron nanoparticles (INP) are often used to treat various types of environmental contaminants. In this study, we synthesized a new class of iron nanoparticles and stabilized it using poly-acrylic acid (PAA). A two dimensional groundwater aquifer model was used to study the fate and transport of pristine INP and SINP (stabilized iron nano particles) under steady-state flow conditions. Transport data for a non-reactive tracer, INP, and SINP were collected under similar experimental conditions. The results clearly demonstrate the ability of PAA to stabilize INP. Furthermore, the transport data indicated that the S-INP plume will sink in a groundwater aquifer, indicating that small density gradients have significant influence on two-dimensional transport. This observation has enormous implication for designing field scale remediation systems that use iron nano particles. We used the variable-density groundwater model SEAWAT to model INP as a density driven tracer. The model results along with the experimental data show that the density influence transport controlled the migration patterns of SINP. Since the influence of density effects cannot be fully discerned using column experiments, two dimensional experiments are essential for fully understanding the transport characteristics of INP.