Experimental investigation of nano zero-valent iron mobility in porous media

In this study, the colloidal stability and mobility of Fe/Ni nano particles, concurrently synthesized and stabilized in the presence of starch (S-nZVI/Ni), were investigated. In particular, the influence of pore velocity (ranging from 7 to 85 m/d) and injected particle concentrations (0.3 and 3 g/l) was evaluated in a one-dimensional column. Experimental results exposed the fine mobility of the S-nZVI/Ni particles in porous materials. According to the breakthrough curves and mass recovery, the S-nZVI travel distance was limited to the range of 0.2 to 0.4 m for low pore velocities (5 to 7 m/d), and in the order of 10 m at higher velocities (> 50 m/d). Moreover, increasing pore velocity enhanced the mobility of S-nZVI. Results also proposed that the mobility of S-nZVI suspension in sand media should be lower than in glass beads media. The clogging phenomenon of the column and the pore pressure variations during the injection period were strongly affected by media type and injected particle concentration. Clogging, due to the deposition of particles, was observed, in particular, for 3 g/l nZVI suspension, low velocities and sand media. Finally, the results indicated that starch stabilized iron nano particles have the potential to become an effective reactive material for in-situ groundwater remediation. (C) 2015 Sharif University of Technology. All rights reserved.