Microbiologically influenced corrosion mechanism of 304L stainless steel in treated urban wastewater and protective effect of silane-TiO2 coating

• Published in: Bioelectrochemistry (Amsterdam, Netherlands) Vol. 132; no. C; p. 107413
• Main Authors: Ziadi, I., Alves, M.M., Taryba, M., El-Bassi, L., Hassairi, H., Bousselmi, L., Montemor, M.F., Akrout, H.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-2020; Elsevier BV; Elsevier
• Subjects: Aeration; Aeration cells; Austenitic stainless steels; Bacteria; Bacterial adhesion; Bacterial corrosion; Biofilms; Coating effects; Coatings; Colonization; Corrosion; Corrosion effects; Corrosion mechanisms; Corrosion prevention; Corrosion resistance; Corrosion resistant steels; Depletion; Dissolved oxygen; EIS; Electrochemical impedance spectroscopy; Electrochemistry; Iron-oxidizing bacteria; Localized corrosion; MIC; Minimum inhibitory concentration; Oxidation; Protective coatings; Scanning electron microscopy; Silane-TiO2 coating; Sol-gel processes; Spectroscopy; Spectrum analysis; Stainless steel; Submerging; Sulfate reduction; Sulfate-reducing bacteria; SVET; Titanium dioxide; Wastewater; Wastewater treatment; Silane-TiO2 coating; Bacterial adhesion; SVET; MIC; Stainless steel; EIS
• ISSN: 1567-5394; 1878-562X
• DOI: 10.1016/j.bioelechem.2019.107413

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•Advanced electrochemical techniques were used to monitor biocorrosion.•Biocorrosion of the stainless steel involves IOB and SRB,amongst other bacteria.•Dissolved oxygen in urban wastewater plays a key role in the corrosion process.•Silane-TiO2 sol-gel coating reduces bacterial adhesion on the stainless steel.
Microbiologically influenced corrosion (MIC) of bare and silane-TiO2 sol-gel coated stainless steel (SS) was studied in treated urban wastewater (TUWW). Combining the electrochemical impedance spectroscopy (EIS) and the scanning vibrating electrode technique (SVET) showed that SS surface colonization occurs, at earlier stages, by iron-oxidizing bacteria (IOB), and later by sulphate-reducing bacteria (SRB). The SVET results showed that chemical corrosion process and bacterial respiration led to the depletion of dissolved oxygen, creating a differential aeration cell and thus a localized corrosion phenomenon. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) showed that the growth of a bacterial biofilm on 304L SS was a dynamic process, stimulating the localized oxidation of SS. To improve corrosion protection, a silane-TiO2 sol-gel coating for SS is proposed. SEM showed that the coating reduced bacterial adhesion and EIS study demonstrated that the coating improved the barrier properties and corrosion resistance of 304L SS in TUWW over a short period of immersion.