Recently, iron nanoparticles have attracted more attention for groundwater remediation due to its potential to reduce subsurface contaminants such as PCBs, chlorinated solvents, and heavy metals. The magnetic properties of iron nanoparticles cause to attach to each other and form bigger colloid particles of iron nanoparticles with more rapid sedimentation rate in aqueous environment. Using the surfactants such as poly acrylic acid (PAA) prevents iron nanoparticles from forming large flocs that may cause sedimentation and so increases transport distance of the nanoparticles. In this study, the transport of iron oxide nanoparticles (Fe3O4) stabilized with PAA in a one-dimensional porous media (column) was investigated. The slurries with concentrations of 20,100 and 500 (mg/L) were injected into the bottom of the column under hydraulic gradients of 0.125, 0.375, and 0.625. The results obtained from experiments were compared with the results obtained from numerical solution of advection-dispersion equation based on the classical colloid filtration theory (CFT). The experimental and simulated breakthrough curves showed that CFT is able to predict the transport and fate of iron oxide nanoparticles stabilized with PAA (up to concentration 500 ppm) in a porous media.
In this paper, considering the accumulation of the sediments on the fl oor of the vortex settling basin during sediment extracting, curvature submerge vanes were used on the fl oor of the vortex basin and the eff ect of the size of the orifi ce was studied on the performance of the curvature submerge vanes for sediment leaching of the fl oor of the basin. Experiments were performed on a physical model with a height of 90 cm and a diameter of 206 cm and a fl oor slope of 10% and also three orifi ces were used with diameters of 59, 46 and 36 mm. The submerge vanes were placed in diff erent arrangements and diff erent radial sections. The results of the experiments indicated that the performance of the vanes in sediment extracting on the fl oor is primarily infl uenced by the orifi ce and secondly by the arrangements and radial sections of the vanes' placements.
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