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Applacation of Zinc Oxide Nanoparticles in Lichen Removal from the Historical Stone Surfaces

Nodeh, Razieh | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47741 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Khorashe, Farhad; Sohrabi, Mohammad; Baghalha, Morteza
  7. Abstract:
  8. There are many archeological sites, historic building monuments and inscriptions in Iran and other countries in the world which have been damaged by environmental as well as biological causes. Lichens are one of the biological causes which, through their growth, bring about change and damage to the stones. Different methods, each of which has both advantages and disadvantages, have been used in order to deal with the problem. Since there are many historic buildings in our country which have been damaged by different biological causes including the lichens, doing a research on the topic seems to be quite significant and necessary. The Persepolis is among one of the most important historic monuments of the country which have been affect by the attack of the lichens and which is the target of the current study. The objective of the project is using ZnO nanoparticles in order to control the growth and decreasing the metabolic activities of the target lichen, that is, Caloplaca biatorina, which could be detected in many historic places including the Persepolis. First some stone samples were collected from Rahmat Mount which was one of the sources from which they collected stones in the ancient times in order to build the Persepolis. Then ZnO nano-particles were synthesized through using chemical precipitation method and by using XRD and TEM tests the nanoparticles were characterized. The results predicted the Chrystal and particle size of the nanoparticles to be 28±2 and 30±2 nm. Then, through using ultrasonic bath, the nanoparticles were dispersed in distilled water and methanol in different concentrations (300, 100, 50 ppm) and the achieved suspensions were applied on stone samples. Finally, the effectiveness of the substance was tested through utilizing different analyzers including digital microscope, microscope, chlorophyll balance test and liquid chromatography. The achieved results show that with the raise of the concentration of the nanoparticles, their effectiveness also raises and the ethanol suspensions of the particles give a better response to watery suspensions. Consequently, the lowest amount of chlorophyll a and the lowest amount of secretion of oxalic acid were detected from the lichen in the treated sample with ethanol suspensions of the nanoparticles
  9. Keywords:
  10. Zinc Oxide Nanoparticles ; Lichen Removal ; Historic Stones ; Persepolis

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