Preparation of Nanoscale Zero-Valent Iron Suspension and Its Transport Model in Saturated Soil Layer
Date Issued
2008
Date
2008
Author(s)
Che, Choi-hong
Abstract
Direct injection zero valent iron method has been widely used for treating chlorinated hydrocarbon contaminated groundwater aquifers. However, the efficiency decreases and the cost rises due to the poor spreading ability of iron particles in the subsurface environment. Therefore, if we can enhance the spreading ability of iron in porous media by adding surface modifier we may increase the applicability of iron particles.e used different stabilizing to produce nanoscale iron suspension by means of batch experiments. Also we evaluated the performance of the stabilizing dispersants. It was found that PAA can get the most stable suspension when the final concentration of PAA and total iron were both 5000 ppm. About 90% of the nano-particles remained in suspension for 28 days. The average particle sizes was 87 nm determined by ZetaSizer. Particle sizes were all found to be around 200 nm and the particles seemed to be wrapped in high oxide-containing stabilizing dispersants under the examination with SEM-EDS. ercolation rates of nanoscale iron particles through the soil was tested using column experiments. The percolation results for soil columns with depth of 10 cm, 20 cm and 30 cm were 75.6%, 61%, and 41%, respectively; and the decay coefficient (κ) of the suspended nanoscale iron particles per unit distance was 0.01 cm-1 transport model of NZVI in saturated soil layer was constructed. The pore structure in soil layer was characterized by the constructed tube model. The absorbing situation of particle of soil surface was determined by trajectory analysis in the constricted tube. The modeling analyses and experimental results indicate that the prediction has over estimated the breakthrough concentration . Simulation value relatively conforms the experimental value when adjusting the diameter of the particles and considering Brownian forces.
Subjects
nanoscale iron particle suspension
PAA
transport model
DLVO theory
porous media
trajectory analysis
Type
thesis
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