TA222 :
Thesis > Central Library of Shahrood University > Civil & Architectural Engineering > MSc > 2014
Authors:
Abstarct: Use of iron nanoparticles are recently considered as removal agents for various pollutants of water and soil due to specific surface and capability of transport in porous media. Despite the remarkable findings in this field, the technology has a long way to become a common practice in engineering due to technical and economical considerations. One of the problems is the strong tendency of bare iron nanoparticles to aggregation, agglomeration, and consequent rapid settlement or filtration on the solid phase surface. A suggested solution for this problem is to coat the bare iron nanoparticles by stabilizers. Another problem is the lack of accurate data about nanoparticle transport mechanism and hydraulics of slurry of nanoparticles in porous media. Very limited data is available on this subject, mainly focused on 1-D physical modeling. Some numerical experiments were also conducted, verified by simple laboratory models.
The goals of this research were to investigate the applicability of the available theoretical models on slurry of nanoparticles in porous media through physical and numerical tests as well as proposing the methods useful for engineering practices. 1, 2, and 3-D physical models were constructed and extensive laboratory experiments were performed. Numerical models as well as digital image processing were employed for further verification of the results and reliable conclusions.
The research results suggest that poly acrylic acid (PAA) with optimized weight ratio 1:2 (1 gr nanoparticle: 2 gr poly acrylic acid) is able to effectively coat the nanoparticle which leads to a stable colloidal mixture in which the nanoparticles remain nano by preventing aggregation and coagulation. High concentrations of nanoparticles (more than 1000 mg/Lit) and reduction in speed rate of passing nanoparticle slurry decelerate the nanoparticle transportation in saturated porous media. The results of numerical simulation of 1-D, 2-D and 3-D transportation of nanoparticle suggested that nanoparticles have colloidal behavior in porous media. The results of measured concentration in the body of the above models showed that MT3DMS, a subsidiary of MODFLOW, is able to accurately simulate the transport of iron oxide nanoparticles (Fe3O4), stabilized with PAA, under classical filter theory (CFT).
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