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Photodegradation of Chemical Pollutants Under UV Light by the Improved TiO2/CNT Nano Photocatalyst Coated on a Porous Substrate

Kordhaghi, Fatemeh | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46259 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Sadrnezhaad, Khatiboleslam
  7. Abstract:
  8. In recent years, semiconductor photocatalysts have attracted much attention because of cleanliness, no secondary pollution and profound oxidation and reduction reactions at room temperature. TiO2 is recognized as the best semiconductor photocatalyst due to its higher photocatalytic activity, nontoxicity, electronic and optical properties, chemical stability and low cost. There are some problems preventing from wide application of titania such as rapid recombination of photogenerated electrons and holes, the lack of visible-light utilization and difficult recovery of photocatalyst. In this study, to overcome these problems, TiO2/MWCNTs nanocomposite was prepared. Carbon nanotubes are considered as a system for electronic transport at the nanoscale because of their electrical property and large specific surface area. The properties of CNTs, such as hollow and layered structures, high mechanical strength and large specific surface area, have caused to CNTs be a suitable supporting material for catalysts. In addition, high electron conduct ability and high adsorption capacity of carbon nanotubes indicate they can act as materials in environmental cleanup. Combination of photocatalytic activity of titanium dioxide with adsorption and charge transfer abilities of carbon nanotubes makes an excellent composite for photocatalytic applications. In present study, TiO2/MWCNTs nanocomposites, with different CNT contents, were synthesized by sol-gel method from TTIP precursor and functionalized carbon nanotubes, and then, were calcined for 2 hours at 470°C under Ar atmosphere. Functionalization of carbon nanotubes was investigated by FTIR spectroscopy. The structure and particle size of synthesized nanocomposites were studied using X-ray diffraction spectroscopy (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). Specific surface area, energy gap, and absorption wavelength of the samples, respectively, measured by BET method and DRS spectra. The photocatalytic efficiency of the composites were determined by UV-vis spectroscopy for the degradation of a 5 ppm methyl orange aqueous solution, and were compared with the pure titania sample. The results showed that the size of titania nanoparticles and energy gap decreases with combination of titania with carbon nanotubes as well as the absorption wavelength and photocatalytic activity increases compared with pure titania. Moreover, by increasing the amount of CNT from 1wt.% to 30wt.%, the particle size of titania decreases, and specific surface area and photocatalytic activity, steadily, increases. Therefore, the composite containing 30wt. % carbon nanotubes showed a high photocatalytic efficiency
  9. Keywords:
  10. Titanium Dioxide Nanoparticles ; Photocatalyst ; Multi-Walled Carbon Nanotube ; Methyl Orange ; Sol-Gel Method

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