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Study on Thermodynamics of Iodine Vapor Adsorption on Cu Nanoparticles by Different Computational Approach

Razavi, Maliheh | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49386 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Outokesh, Mohammad
  7. Abstract:
  8. Iodine isotopes are among the most significant medical radioisotopes with a wide range of applications in therapy and diagnosis. The I-131 isotope is usually synthesized by irradiation of natural tellurium in atomic reactors. But there is an alternative route in which this isotopes is produced along with two other significant medical radioisotopes (i.e. Mo-99, Xe-131) by neutronic irradiation of uranium in the reactors. To separate iodine isotopes especially in the extraction process of fission fragments, it is necessary to be selective adsorption of iodine on a selective adsorbent. One of the most selective adsorbent for this application is copper. The aim of this study is to compare the thermodynamics of copper nanoparticles and microparticles that are on iodine uptake. In evaluation of Gibbs free energy changes in reactions such as oxidation and adsoption, metallic nanoparticles surface energy in different sizes is considered constant. But with decreasing size of nanoparticles surface to volume ratio will increase and as a results surface atoms play important role in thermodynamic parameters, so surface energy can not be constant in different size. The surface energy of metallic nanoparticles has been extensively investigated, both as theoretically and experimentally, but different approaches may lead to the different results. Indeed, despite the abovementional extensive investigation, there is still a need for a complete model of the surface energy of the metallic nanoparticles that can account for its dependency on the particle sizes. In this thesis, at first different theories has been investigated and the introduction of a new theory has been created. Metallic nano-clusters surface energy as a function of size, shape and temperature using molecular dynamics simulation in lammps software is calculated. It was established that surface energy decreases with increasing of cluster size, but grows with elevating of the temperature. It was also revealed that for larger nanoclusters surface energy is more sensitive to variation of temperature than one in case of small nanoparticles. Finally the effect of size, shape and temperature dependent surface energy on Gibbs free energy changes in copper and iodine reaction was examined
  9. Keywords:
  10. Surface Energy ; Nanoparticles ; Gibbs Free Energy Minimization ; Molecular Dynamic Simulation ; Selective Absorption ; Iodine Adsorption ; Energy Size Dependent ; Energy Shape Dependent

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