Theses and Dissertations at Montana State University (MSU)
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Item Biocorrosion of copper by Oleidesulfovibrio alaskensis G20 biofilms in static and dynamic environments(Montana State University - Bozeman, College of Engineering, 2024) Keskin, Yagmur; Chairperson, Graduate Committee: Brent M. Peyton; Matthew Fields (co-chair); This is a manuscript style paper that includes co-authored chapters.This study presents a detailed examination of the intricate relationships between Oleidesulfovibrio alaskensis G20 and copper (101), emphasizing three interconnected perspectives: the kinetics of copper toxicity in three distinct media, the impact of surface finishing on microbiologically influenced corrosion (MIC), and the interaction of G20 biofilms and copper in CDC biofilm reactors. Initially, the study concentrates on the kinetic effects of copper toxicity on the growth of G20. The research meticulously quantifies the detrimental impact of different copper (II) concentrations (6, 12, 16, and 24 micron) on bacterial growth kinetics in three media: LS4D balanced (BAL), electron acceptor-limited (EAL), and electron donor-limited (EDL). Using a non-competitive inhibition model, I50 (concentrations of copper causing 50% inhibition of bacterial growth) values were calculated to be 13.1, 13.87, and 11.31 micron for LS4D BAL, EAL, and EDL media, respectively. The second part of the study shifts its focus to the effect of surface finishing on MIC of copper 101 by G20. The biofilm and corrosion pit depths were measured through a series of sophisticated analyses employing 3D optical profilometry, Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX), and X-ray Diffraction Analysis (XRD). The research investigates how different levels of surface roughness, applied through metallographic grinding and polishing, influence corrosion. The findings demonstrate a clear pattern of both uniform and pitting corrosion across all surface finishes. Notably, a statistically significant decrease in corrosion rates was observed when the surface roughness of copper was altered from approximately 13?m to about 0.06?m. Finally, the study explores the interaction between G20 biofilms and copper (101) into CDC reactors to understand biofilm development on copper surfaces and its subsequent impact on copper corrosion in a dynamic environment over periods of 7, 9, and 14 days. The results showed robust biofilm formation through hexose and protein analyses and SEM images displaying progressive increases in SRB cell accumulation over time. Localized pit depths were measured and compared to static conditions, and pits showed only a 20% increase in a dynamic environment. These findings offer an improved understanding of the complex interactions between G20 and MIC of copper.Item Biocorrosion of 1018 steel in sulfide rich marine environments: a correlation between strain and corrosion using electron backscatter diffraction(Montana State University - Bozeman, College of Engineering, 2014) Martin, Joshua Daniel; Chairperson, Graduate Committee: Paul E. GannonMicrobially induced corrosion (MIC) of steel due to the presence of sulfide is a leading cause of pit formation of carbon steel in fuel-seawater environments. While extensively studied, the exact causes of pitting corrosion in naval fuel tanks when exposed to MIC in the presence of fuel and seawater are not completely understood. This thesis focuses on the role that cold-rolling of carbon steel plays on corrosion while subjected to sulfidogenic, suboxic corrosive environments. Particularly, the effects of microscopic residual strain found within 1018 steel on the anodic dissolution of the metal is studied in different MIC sulfide environments using EBSD, AFM, FE-SEM, EDX, and electrochemistry. It is found that regions of increased plastic deformation of the crystalline lattice as a result of cold rolling correlate to an increase in anodic dissolution rates of 1018 steel coupons cut parallel to rolling direction. Image overlay provides a verification of the location of corrosion of samples to the same locations found in EBSD mapping taken prior to corrosion, ensuring the predictive value of EBSD analysis in establishing locations of accelerated corrosion. The effect of different corrosion environments on the corrosion rate of steel is measured through electrochemistry. Values obtained through these measurements are applied using mechanochemical theories to predict the localized dissolution rate of the steel due to strain using computational methods. Mechanochemical analysis of the strained areas results in predicted corrosion rates within an order of magnitude of the corrosion rates measured using AFM for the exposed time period at the same locations. Areas exhibiting increased corrosion rates occur in areas exhibiting increased strain as measured by EBSD analysis. Further electrochemical results show an increase in corrosion rates for suboxic sulfide rich systems containing low levels of oxygen, when compared to anaerobic sulfide environments. Variations in corrosion current density as a function of oxygen presence, as measured by electrochemistry, accurately predict variations in mechanochemical corrosion rates of strained areas well within an order of magnitude. Results from this study support the use of EBSD as a means to further the understanding of pitting corrosion as a function of material properties.Item Autohydrolysis and deligninfication of wheat straw(Montana State University - Bozeman, College of Engineering, 1985) Nakaoka, Ronald KurtItem Physiological and environmental factors affecting biofilm formation and activity in vapor phase bioreactors(Montana State University - Bozeman, College of Engineering, 1995) Mirpuri, Rajesh G.Item Mechanism of lubricating oil degradation in presence of plant oil(Montana State University - Bozeman, College of Engineering, 1986) Dutta, AbhijitItem Isolation and characterization of thermostable alkaline bacteria with ligninolytic potential(Montana State University - Bozeman, College of Engineering, 2012) Popovitch, Ari Elizabeth; Chairperson, Graduate Committee: Brent M. PeytonThermus thermophilus ST and S42 were isolated from high pH (9) and temperature (70°C) hot springs in the Alvord Desert, Oregon and the Heart Lake Geyser Basin in Yellowstone National Park, Wyoming, respectively. The two strains exhibited lignin degrading potential at pH 9 and 70°C, due to their ability to utilize the lignocellulose degradation products kraft lignin, ferulic acid, cinnamic acid, and p-coumaric acid for growth. Growth on the soluble fraction of alkaline pretreated lignocellulose sources, corn stover, corn cob and lodgepole pine was evaluated. The two isolates grew to higher cell yields due of the presence of kraft lignin, corn stover and lodge pole pine when supplemented with glucose. Dye decolorizing activity was confirmed with Remazol Brilliant Blue R (RBBR), an industrial dye and lignin analog compound. Laccase mediated 2,2' azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) activity was observed for both isolates when 0.05 mM CuSO 4 was supplemented to the growth medium. Ligninolytic bacteria capable of growth at pH 9 and 70°C are potentially useful with alkaline lignocellulose pretreatment methods to depolymerize and remove lignin prior to the production of second generation biofuel.