Understanding biofilm impact on electrochemical impedance spectroscopy analyses in microbial corrosion and microbial corrosion inhibition phenomena

• Published in: Electrochimica acta Vol. 426; p. 140803
• Main Authors: Moradi, M., Ghiara, G., Spotorno, R., Xu, D., Cristiani, P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 10.09.2022
• Subjects: Biofilm; Differential impedance analysis; Electrochemical impedance spectroscopy; EPS; Microbial corrosion; Microbial corrosion; Biofilm; EPS; Differential impedance analysis; Electrochemical impedance spectroscopy
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2022.140803

•EEC from EIS data on MIC were estimated by differential impedance analysis.•Biofilm does not constitute a time constant in EIS analyses on MIC cases.•Biofilm impacts on charge transfer and double layer capacitance.•Biofilm modifies the nature of corrosion products affecting film electrical properties.•Concentrated EPS (10 g/L) behaves more like a synthetic polymeric coating. Electrochemical impedance spectroscopy (EIS) is a non-disruptive technique that can be used to assess the corrosion behavior of materials. In this work, case studies on microbial corrosion (MIC) and microbial corrosion inhibition (MICI), drawn from the recent literature, were re-elaborated and discussed to determine which underlying information EIS analysis could or could not provide, concerning the roles of biofilms and bacteria on the corrosive and inhibitive processes. The data were suitably integrated and elaborated upon using Differential impedance analysis (DIA) to estimate the maximum number of time constants (T) that constituted the electric equivalent circuit (EEC) of each considered corrosion process. Additional analyses on the corrosion products performed by XPS and EIS showed that the bacterial biofilm had a significant influence on the faradaic charge transfer and film resistance of the corrosive process, as well as on its inhibition, at the metal-biofilm interface; however, it did not constitute an additional time constant.