Study of Microbially Influenced Corrosion in the Presence of Iron-Oxidizing Bacteria (Strain DASEWM2 )
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Study of Microbially Influenced Corrosion in the Presence of Iron‑Oxidizing Bacteria (Strain DASEWM2) Reena Sachan1 · Ajay Kumar Singh1 · Yuvraj Singh Negi2 Received: 19 April 2020 / Revised: 24 July 2020 / Accepted: 7 August 2020 © Springer Nature Switzerland AG 2020
Abstract The present study deals with the investigation of microbially influenced corrosion of mild steel by the iron-oxidizing bacterium (IOB), Pseudomonas sp. strain DASEWM2, using electrochemical tests, immersion tests, and surface analysis. The corrosion rate obtained by Tafel plots was higher after exposure of ~ 24 h to 72 h when the concentration of sessile cells and constituents of extracellular polymeric substances were high. In inoculated media, cyclic polarization curves show lower pitting potential, repassivation potential, and large area under the hysteresis loop, indicating higher susceptibility of steel to localized corrosion. Immersion tests show higher corrosion rate (0.252 ± 0.05 mpy) and large deep pits in the open area (maximum pit depth 140 ± 8 µm) and under crevice (maximum pit depth 95 ± 4 µm) indicating a higher degree of corrosion in inoculated media. Corrosion products formed on corroded steel samples were analyzed using EDAX, XRD, and FTIR techniques. Goethite and lepidocrocite are the main corrosion products in the case of inoculated media. In contrast, lepidocrocite and iron hydrogen phosphate are the main corrosion products in the case of control media. The absence of iron hydrogen phosphate, a protective type of corrosion product, on steel exposed to inoculated media may be responsible for observing a higher degree of corrosion due to bacteria. Keywords Mild steel · Iron-oxidizing bacteria · Biofilm · Corrosion tests · XRD · FTIR
1 Introduction Microbial influenced corrosion (MIC) is a center point of attraction for researchers during the last two decades due to the huge economic losses [1]. MIC is the destruction of metallic and non-metallic materials, caused by the microbes [2]. Bacteria produce biofilm and result in the irregular physico-chemical conditions of different sites of a metal surface [3]. MIC involves different processes by which the microbes cause corrosion either directly or indirectly. According to a study, the progress of MIC involves extracellular electron transfer (EET) by biofilm formed in the vicinity of metal [4].
* Reena Sachan [email protected]; [email protected] 1
Department of Applied Science and Engineering, Indian Institute of Technology Roorkee, Saharanpur Campus, Saharanpur, U.P. 247001, India
Department of Polymer and Process Engineering, Indian Institute of Technology, Roorkee, Saharanpur Campus, Saharanpur, U.P. 247001, India
2
According to Flemming, MIC is responsible for 20% of corrosion costs [5]. Biofilm is the main culprit for MIC [6]. Microbes are ubiquitous and can damage the equipment and infrastructure in different environments such as water distribution system [7, 8], oil and gas industries [9–11], marine environments [11], nuclear waste storage facilit
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