Corrosion of Q235 Carbon Steel in Seawater Containing Mariprofundus ferrooxydans and Thalassospira sp.

Shiqiang Chen,Guangzhou Liu,Dun Zhang,Hao Deng

doi:10.3389/fmicb.2019.00936

Abstract

Iron-oxidizing bacteria (IOB) and iron-reducing bacteria (IRB) can easily adhere onto carbon steel surface to form biofilm and affect corrosion processes. However, the mechanism of mixed consortium induced carbon steel corrosion is relatively underexplored. In this paper, the adsorptions of IOB (Mariprofundus ferrooxydans, M. f.), IRB (Thalassospira sp., T. sp.) and mixed consortium (M. f. and T. sp.) on surface of Q235 carbon steel and their effects on corrosion in seawater were investigated through surface analysis techniques and electrochemical methods. Results showed that local adhesion is a typical characteristic for biofilm on surface of Q235 carbon steel in M. f. and mixed consortium media, which induces localized corrosion of Q235 carbon steel. Corrosion rates of Q235 carbon steel in different culture media decrease in the order: rM.f. > rmixed consortium > rT. sp. > rsterile. The evolution of corrosion rate along with time decreases in M. f. medium, and increases then keeps table in both T. sp. and mixed consortium media. Corrosion mechanism of Q235 carbon steel in mixed consortium medium is discussed through analysis of surface morphology and composition, environmental parameter, and electrochemical behavior.

Highlights

Carbon steel, as a common material in marine engineering, is vulnerable to corrosion
These behaviors indicate that the evolution of Open circuit penitential (OCP) of Q235 carbon steel in mixed consortium medium is closely related with the presence of T. sp
In M. f., T. sp., and mixed consortium media, the average weight loss is larger than that in sterile medium after 1 day of exposure, indicating that the presence of bacteria promotes the corrosion of Q235 carbon steel (Figure 2B)

Summary

Introduction

As a common material in marine engineering, is vulnerable to corrosion. Iron reducing bacteria (IRB) and oxidizing bacteria (IOB) are two kinds of special microorganisms using iron as an electron acceptor and donor, respectively, (Byrne et al, 2015). IRB combine reduction of Fe(III) with oxidation of organic matter or H2 for energy conservation, i.e., IRB readily use dissolved Fe(III) complexes or short-range-ordered minerals (e.g., ferrihydrite) and even magnetite as terminal electron acceptors (Pan et al, 2017; Fortney et al, 2018). IOB grow with Fe(II) or H2 as the electron donor coupled to the reduction of oxygen in environments at acidic and circumneutral pH values (Weber et al, 2006; McBeth and Emerson, 2016).

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Results

Conclusion