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Experimental Investigation of Mobility and Reactivity of Iron Nanoparticles in Porous Media and Application for in-Situ Groundwater Remediation

Fadaei Tehrani, Mohammad Reza | 2015

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 47355 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Shamsaei, Abolfazl; Vosoughi, Manoochehr
  7. Abstract:
  8. In the present study, synthesis, preparation, and application of bimetallic iron/nickel nano-particles were experimentally investigated with the aim of groundwater remediation. Firstly, iron/nickel nano-particles were synthesized according to chemical reduction and stabilization with starch biopolymer, and then characterized. Results confirmed the formation of bimetallic iron/nickel nano-particles with mean size of 75 nm that starch placed around of them. The more stability characteristic and also enough mobility ensure their diffusion through porous media. Secondly, reactivity of synthesized nano-particles for removal of various contaminants including nitrate, chromium, and lead were examined. These experiments were replicated in different conditions including batch and continuous flow. According to the outcomes, iron/nickel nano-particles had a considerable ability to remove the studied contaminants so that an efficiency of up to 99 percent were observed. Solution pH, nickel content, freshness and concentration of the injected nano-iron, contact time, seepage velocity, and ionic strength of the medium were determined as the main variables affecting the process of contaminants removal. As a comparison, the experiments in bench-scale model reported an efficiency of pollutant removal of up to 18 percent lower than experiments at the same conditions in transparent model. This could be attributed to the effect of groundwater ionic strength and the competition of other ions and substances for receiving electron from iron/nickel nano-particle and also inadequate dispersion of nano-particles in sand porous medium. Finally, mobility pattern and dispersion of the iron/nickel nano-particle plume were investigated in one- and two-dimensional physical models of porous media in a wide range of seepage velocity, type of porous media, and nano-particle type. To calculate the hydrodynamic coefficients of dispersion and delay, a novel combination of image processing and least sum of squares algorithm was applied, in addition to direct measurement of iron/nickel nano-particle concentration. Based on the results bare iron nano-particles attached immediately to the porous media and became immobile, stabilized iron nano-particles had a considerably higher mobility and stability to migrate along with groundwater flow. Analyses showed that effective transport length of iron nano-particles in porous media, depending on porous media properties, iron nano-particle stabilization method, and seepage velocity, was varied in the range of 1 to 12 meter
  9. Keywords:
  10. Iron Nanoparticle ; Image Processing ; Mobility ; Reactivity ; Nano Zero Valent Iron (NZVI)Particle ; Hydrodynamic Dispersion

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