Microbial Biosurfactant as Sustainable Inhibitor to Mitigate Biocorrosion in Metallic Structures Used in the Offshore Energy Sector

Microbiologically influenced corrosion (MIC) represents a critical challenge to the integrity of pipelines, piping, and metal structures in offshore environments, directly affecting the safety and operational costs of companies in the energy sector. However, conventional control methods, such as the use of chemical inhibitors, raise environmental and economic concerns. To face this problem, a biosurfactant produced by Pseudomonas cepacia CCT 6659 was tested as a biocorrosion inhibiting agent on carbon steel specimens immersed in seawater. For this purpose, static and dynamic conditions were simulated using different concentrations of the biosurfactant. Furthermore, analyses were performed using Scanning Electron Microscopy paired with Energy Dispersive Spectroscopy (SEM/EDS) to visualize the morphology of the biofilm and its chemical components. Laboratory tests indicated that the biosurfactant formulated in a 1:5 (v/v) ratio reduced the mass loss of test specimens (119.72 ± 2.64 g/m2) by no less than 57.3% compared to the control (280.28 ± 4.58 g/m2). Under dynamic conditions, the 1:2 (v/v) formulation showed greater protection, being able to reduce specimen corrosion (578.87 ± 7.01 g/m2) by 69.6% compared to the control (1901.41 ± 13.53 g/m2). SEM/EDS analyses revealed changes in surface composition and a reduction in corrosive elements associated with sulfur in the formed biofilms, which may be associated with a decrease in sulfate-reducing bacteria (SRB) activity, suggesting microbial inhibition by the biosurfactant. The results obtained in this study highlight the biosurfactant as a viable and ecological alternative to synthetic inhibitors, with potential application in the protection of metal structures exposed to corrosive environments in offshore energy systems, promoting greater durability, sustainability, and less environmental impact.