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Master's Thesis-Zahra Nabati.pdf (4.5 MB)

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Effect of Yarrowia Lipolytica biofilm on corrosion behavior of carbon steel in simulated biodiesel storage tanks

Nabati, Zahra
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513356814768246

Abstract Details

2017, Master of Science, University of Toledo, Chemical Engineering.
Microbial contamination occurs in various stages of the petroleum refining process. However, these microbes commonly end up in fuel storage tanks and grow rapidly in the presence of water and other favorable conditions within the tanks. Petroleum consists of a mixture of hydrocarbons, small amounts of inorganic compounds, and traces of metal salts. Microbes utilize these compounds to grow, especially in the oil/water interface region. Among various types of fuel, biodiesel contains a mixture of fatty acid methyl esters (FAME), which facilitates the microbes’ ability to thrive in this environment. The tendency for biodiesel to dissolve in water also provides a desirable environment for microbial growth. Hence, there have been great concerns regarding biodiesel quality deterioration due to formation of biofilms in biodiesel storage tanks. Biofilm attachment to the metal’s surface alters the conditions at metal/solution interface and changes the corrosion behavior of metal. Biofilm growth may either inhibit or promote the corrosion. Yarrowia lipolytica is a strictly aerobic yeast which can utilize hydrocarbons as its’ sole source of carbon and it has been reported to be found in oil systems (specially in fuel storage tanks). This microorganism is also known for its capability of high lipid accumulation and has application in biodiesel production which is well known in literature. However, to our knowledge there is lack of studies on the effect of Yarrowia lipolytica in biofilm formation and corrosion process of fuel storage tanks. In this study, we investigated the effect of Yarrowia lipolytica biofilm formation on the corrosion behavior of carbon steel in simulated storage biodiesel tanks. Yarrowia lipolyica isolated from a fuel storage tank was inoculated in testing cells containing B20 and Bushnell-Hass media. The biofilm growth was monitored in the cells using imaging techniques. Various corrosion-testing methods such as weight loss analysis, electrochemical techniques including open circuit potential measurement, electrochemical impedance spectroscopy (EIS), potentiodynamic scan, as well as have been used to measure the corrosion rate and evaluate the corrosion behavior of carbon steel. Also, surface analysis and material characterization methods were utilized to monitor biofilm development and corrosion product formation at the metal’s surface. Our results showed a significant corrosion potential in the biofilm cells during the initial stage of the experiments, possibly due to patchy biofilm formation with channels and pores which provides suitable conditions for the ion and electrolyte transfer to the metal’s surface. However, a prolonged and confluent biofilm development resulted in decreased electrolyte transfer as well as depletion of oxygen from the electrolyte and thereby a substantial decrease in the corrosion rate. For control cells, the oxidation of the metal resulted in the production of a corrosion film (coatings). This film was constantly breaking down and re-sealing itself, so it could still maintain adequate transfer of ions and electrolytes and thereby acceleration of corrosion. However, the results showed a decrease in corrosion rate from day 96 which was possibly due to excessive accumulation of corrosion products and lower surface-electrolyte contact availability of metals. Overall, the results of the study suggest that prolonged development of yeast Yarrowia lipolytica biofilm may have an inhibitory effect on the corrosion rate of carbon steel.
Youngwoo Seo (Committee Chair)
Joseph Lawrence (Committee Co-Chair)
Dong-Shik Kim (Committee Member)
115 p.
Chemical Engineering; Engineering
Microbial contamination, Fuel contamination, MIC, Microbial induced corrosion, Biodegradation, Biocorrosion, biofilm, Yarrowia lipolytica, Corrosion in fuel storage tanks

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Citations

  • Nabati, Z. (2017). Effect of Yarrowia Lipolytica biofilm on corrosion behavior of carbon steel in simulated biodiesel storage tanks [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513356814768246

    APA Style (7th edition)

  • Nabati, Zahra. Effect of Yarrowia Lipolytica biofilm on corrosion behavior of carbon steel in simulated biodiesel storage tanks. 2017. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513356814768246.

    MLA Style (8th edition)

  • Nabati, Zahra. "Effect of Yarrowia Lipolytica biofilm on corrosion behavior of carbon steel in simulated biodiesel storage tanks." Master's thesis, University of Toledo, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513356814768246

    Chicago Manual of Style (17th edition)

toledo1513356814768246
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This open access ETD is published by University of Toledo and OhioLINK.