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Investigation of Application of Nano-Photocatalytic Degradation for Industrial Wastewater Treatmen

Falahati, Mohammad | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47049 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Roosta Azad, Reza; Vossoughi, Manouchehr
  7. Abstract:
  8. The main objective of this project is the deposition of photo-catalysts on cement and concrete blocks with an emphasis on commercialization. We started with an extensive study of common methods introduced in previous literature, and conclude with a number of suggestions for industrialization. First, slurry and sol-gel deposition of the photo-catalysts on blocks of type 2 commercial cement which is one of the most used materials in construction of buildings and waste-water treatment plants has been examined to reach a method of sample formation. Due to the simplicity of common methods and low quality of formed samples (less than 5 percent aging efficiency), the obtained experience was used to develop a novel method of deposition, which can be called adsorption method. In this method, by optimizing the contact time of cement and catalyst and also the dispersion of catalyst on the surface of the cement blocks, two main parameters of perfect deposition, namely high degradation efficiency and high stability of catalyst on the surface, have been obtained. Next, the commonly used methods were compared to the suggested method for common construction cements (Pozolani cement, White cement, Sarbareh cement and type2 Portland cement) to degrade a solution of methylene blue with concentration of 10 ppm in order to find the best surfaces for deposition. Based to the type of the cements and their components, remarkable results have been achieved. Using characterization tests including SEM and XRD, mechanisms have been proposed, evaluated and proved. In conclusion, White cement because of its small particles, has a high efficiency of catalyst trapping on its surface. As for catalyst deposition on concrete blocks, because of their rough and unsmooth surface, absorption method is not comparable between various samples. Therefore we focused mostly on the optimization of common methods. Among the cement samples that were shaped with sand, Pozolani concrete showed the best efficiency of deposition. Long curing procedure could contribute to this high efficiency since the longer contact time allows for the formation structures with catalyst, SiO2 and CaO. On the other hand, the occurrence of undesirable events like pH variations have been studied and some suggestions have been proposed to prevent them. Finally, to quantify the stability of the deposited samples, Aging procedure has been performed on the most catalytically efficient samples by comparing the efficiency of the deposited samples that were degrading the waste-water for 200 hours, with fresh samples. Using this method he degree of catalyst loss and subsequently the deposition efficiency was calculated (Aging efficiency of 99 percent and photocatalytic oxidation efficiency of 66 percent)
  9. Keywords:
  10. Cements ; Concrete ; Industrial Wastewaters ; Waste Treatment ; Deposition ; Nanophotocatalyst

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