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The Selection of Appropriate Method for the Degradation of Microplastics

Pourjafar Biazar, Fatemeh | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57209 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Yaghmaei, Soheila; Ghobadinejad, Zahra
  7. Abstract:
  8. Microplastics are pollutants that are very resistant to natural decomposition and have become a threat to human health by entering the food chain and accumulating in the body. In this research, the second stage of the two-stage treatment of light density polyethylene microplastics was carried out to investigate the effect of pre-treatment on the removal efficiency of this pollutant. For this purpose, the microplastic samples, which were subjected to a pre-treatment stage with advanced oxidation processes, were again subjected to biological degradation by a bacterial consortium for 2 months. The pretreatment processes used were Fenton and Feredfenton reactions, and the bacterial consortium consisted of two bacteria, Bacillus pumilus and Proteus mirabilis. The results of the field emission-scanning electron microscopy (FE-SEM) test indicated severe physical destruction and fractures of microplastic particles and also showed the formation of biofilm on the surface of microplastics. The decrease in the percentage of crystallinity, which was determined by X-ray diffraction test (XRD), indicated the microbial attack on the crystalline regions of the polymer. The interpretation of the Fourier transform infrared (FTIR) spectrum revealed the reduction of amorphous regions and the emergence of aromatic groups, a result that was confirmed by analyzing the results of the gas chromatography-mass spectrometry (GC-MS) test and attributed to the release of polymer additives due to the weakening of the polymer structure. Finally, the reasons for the low yield of this method were the difficulty of destroying the polymer crystalline region for the biological agent, and the competition of polymer additives with polyethylene chains as the main substrate
  9. Keywords:
  10. Microplastics ; Advanced Oxidation Process ; Low Density Poly Ethylene(LDPE) ; Biodegradation ; Fenton Method ; Proteus Mirabilis Ksh4 Bacteria ; Bacillus Pumilus Ksh3 Bacteria

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