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Removal of Volatile Chlorinated Compounds (TCE,PCE) from Groundwater with Nanostructure of NZVI

Ghasemipoor, Amir | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49253 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Bastani, Darioush; Seifkordi, Ali Akbar; Samiee, Leila; Dastgheib, Mohammad Mehdi
  7. Abstract:
  8. In recent years, the reductive dehalogenation of the chlorinated hydrocarbons using nanoscale zerovalent iron (nZVI) represents a promising approach for underground remediation. Regarding commercialization of this technique, instability and unknown nature of nZVI particle are still challenging tasks that should be considered.
    In the current work, Nanoscale zero-valent iron (nZVI) and palladized iron (Pd/Fe) bimetallic particles were synthesized and employed to react with chlorinated compound (PCE) in water to investigate its degradation behaviors. The results show that the reactant ratio, stabilizer amount and temperature are the main parameters with the considerable effect on PCE degradation, based on the released Cl- measurement. The NaBH4/FeSO4 ratio, CMC amount, and temperature were optimized to 3, 25% and 5°C, respectively. The nanoparticles prepared based on optimized conditions have a high surface area, good stability as well as high dechlorination activity.Also, considering economic and environmental issues, 0.5% was selected as the optimum ratio of Pd catalyst.Moreover, The physyco-chemical properties of the catalysts were studied using X-ray Diffraction (SAXRD), Scanning Electron Microscopy (SEM), EDS, map and nitrogen adsorption–desorption analysis. The particle size, surface area (BET), Fe percentage for the optimized catalyst was obtained as the: 20-12 nm, 96.2 m2/g, and 73%, respectively. Furthermore, the kinetic analysis indicated that the adsorption process was successfully fitted with the pseudo-second-order kinetic model and the intera-particle diffusion was introduced as the controlling step of diffusion. Finally, the obtained results from proceessing parameters revealed adsorbent dose:5 g/l and PCE amount: 5 ppm are the optimized conditions for PCE removal efficiency.Also in in continuous part of our project to dechlorinate chlorinated substances two beds are settled one in presnt of nanoparticles and other without it.parameters that can effect on our result are assumed such pH,Chloride ion and C/CO of tetrachloroethylene achieved by GC.Three parameters are detect in continuous forms: Concentration of nanoparticles in three stage(10و 5و2.5g/l) , seepage velocity of contaminated water passed through bed(2.5.5.1 ml/min) and initial pH (5,6.5 ,8).We conclude nanoparticle concentration of 10g/l,velocity of 2.5 ml/min and pH 5 had the highest efficiency for removal of tetrachloroethylene of groundwater contraminants
  9. Keywords:
  10. Trichloroethylene ; Nano Zero Valent Iron (NZVI)Particle ; Permeable Reactive Barriers ; Groundwater ; Volatile Organic Compound (VOC) ; Polytetrachloroethylene

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