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Title:	Diversity of bacteria in crude oils and determination of corrosion potential for microbiologically influenced corrosion on carbon steel
Authors:	Ali Abd Sharad Al-Khafaji (P70497)
Supervisor:	Asmat Ahmad, Assoc. Prof. Dr.
Keywords:	Microbial biotechnology Microbiological techniques Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	18-Jan-2017
Description:	The main aim of this study was to isolate, identify the bacterial community presents in crude oil field, to determine the bacterial group that might be implicated in corrosion processes and mitigations of potential corrosion effects by using marine bacterial extract.The 16S rRNA gene 454-pyrosequencing technology was used to identify bacterial community in crude oil field (PETRONAS Refinery (Melaka) Sdn. Bhd.). Electrochemical and surface analytical techniques were conducted to determine corrosion potential and corrosion products. Microbial communities in crude oil sample were dominated by Enterobacteriales, Clostridiales, Burkholderiales, Desulfovibrionales, Pseudomonadales, Alteromonadales, Oceanospirillales, Thermotogales, Lactobacillales and Aeromonadales. Out of 452 isolates of crude oil samples, 33 were selected for further analysis based on their ability to strongly causing bio-corrosion induced by high hydrogen sulfide production and also strong biofilm formation. The identification of these isolates using 16S rRNA gene sequencing showed, twelve isolates were identified as Enterobacter cloacae, followed by Citrobacter freundii (5), Halomonas aquamarina (3), Marinobacter hydrocarbonoclasticus (3), Serratia marcescens (3), Salmonella enterica (1), Pseudomonas balearica (1), Virgibacillus pantothenticu (1) Shewanella chilikensis (1), Shewanella algae (1), Disulfovibrio sp. (1), and Clostridium sp.(1). The results from both potentiodynamic polarization and weight loss methods confirmed that the ability of all 33 isolates consortium to induce corrosion was higher than the sulfate-reducing bacteria (SRB) consortium or by the iron reducing bacteria (IRB) consortium. Desulfoviberio sp. had a higher ability to cause corrosion compared with each Clostridium sp., S. chilikensis or S. algae. SEM analysis of the carbon steel surface showed the presence of bacterial biofilms and corrosion product. Energy dispersive X-ray spectroscopy (EDX) elemental analysis of corrosion products indicated that significantly high amount of iron, sulfur and oxygen were produced when SRB present in the culture while high amount oxygen and iron were produced in when IRB present only .The X-ray Diffraction (XRD) spectra of carbon steel coupons exposed to SRB solution indicated the formation of iron sulfide compounds such as mackinawite, iron sulfide, and siderite. Iron oxide-hydroxide compounds including goethite, wustite, magnetite and hematite were formed when the carbon steel coupons were exposed to IRB solution. Ethyl acetate extract of Alcaligenes faecalis (AF) showed highest antibacterial activity against seven (out of 33) selected isolates and against SRB. In addition the results exhibited that, AF achieved high significant effect for inhibiting growth, biofilm formation and biocorrotion in MIC 3.2 mg / ml against the concerned Desulfovibrio sp. and AF showed immediate killing effect against SRB. The GC-MS Chromatography analysis detected the presence of antimicrobial, antifungal, antioxidant and anticorrosion compounds. The most abundant of organic compounds for antimicrobial activity from A.faecalis were pentadecanoic acid and phenol, 2,4-bis(1,1-dimethylethyl).The microbiologically influenced corrosion (MIC) information from this study will improve controlling and prevention strategies which will direct the future research for the development environmentally friendly of antibiocorrosion activity compounds against MIC-related issues in oil and gas industry.,"Certification of Master's/Doctoral Thesis" is not available,Ph.D.
Pages:	316
Call Number:	QR53.K483 2018 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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