Transfer of TiO2 Nanoparticles in Undisturbed Soil Columns: Effect of Flow Rate

Due to limitations of laboratory tools and difficulty in interpreting the results obtained from complex porous media such as soil, artificial porous media such as glass beads, pure sand and quartz and riverbed sand are oftenly used to investigate the transfer of nanoparticles in porous media. In this study, the effect of different flow rates on transfer of titanium dioxide nanoparticles was investigated in the undisturbed soil columns. The flow rate equal to 100, 90, 70 and 50% of the saturated hydraulic conductivity were applied on the soil columns by the peristaltic pump (BT100-1F). By measuring the breakthrough curves for each column, the parameters explaining the transfer of nanoparticles based on a one-site sorption model, one-kinetic site sorption model, and a two-kinetic site sorption model were determined. The results indicate by increasing the flow rate, the reltive concentration of TiO2 nanoparticles (C/Co) in the soil column increases from 3% to 28%. Among the three studied models, the two-kinetic site sorption model which consider the physical straining mechanism based on the particle size and porosity of the porous medium, the function of saturation of the porous media particles with nanoparticles and the physical straining function considering changes of this mechanism with distance, shows the best fit (R2>%90) for estimation of the nanoparticles transfer in the soil column.