Microbiologically influenced corrosion (MIC) is considered one of the major causes of oil and gas pipeline failures, costing billions of dollars annually. Despite the increasing research attention attracted to this area, in-situ detection and monitoring of MIC in real time has presented difficulties, due to the complexity of the corrosion processes resulted, directly or indirectly, from the ever evolving metabolic activities of microorganisms. In this work, an amperometric electrochemical biosensor based on a conducting polymer and carbon nanotubes was developed for detection and monitoring of hydrogen sulfide that can be generated by sulfate reducing bacteria, the main culprits of MIC. The single-walled carbon nanotubes (SWCNT s) are functionalized by a conductive polymer - a polythiophene derivative, which enables the formation of carbon nanotube-polymer nanocomposite sensing layer with enhanced signal transduction capability. A cross-linking agent in optimized dosage was used to improve the water stability of the sensing layer without compromising its electric conductivity. Fast detection of sulfide was achieved with good sensitivity, attributed to the large active surface area of carbon nanotubes and excellent conductivity of the nanocomposite sensing layer. The sensor developed paved the way for further development of online sensors for monitoring MIC.
Microbiologically influenced corrosion (MIC), resulting from activities of microorganisms in the biofilms formed on metal surfaces, has been considered a significant factor contributing to failures of infrastructures (~20% failure)1 including oil and gas pipelines. Despite decades of research efforts, the causes of MIC are still not well understood, mainly due to the complicity of the degradation processes involving multiple and/or multi-stage biological, physical, chemical, and electrochemical reactions on metal surfaces. Full dissection and characterization of MIC requires in-depth understanding of MIC mechanisms and utilization of microbiological, surface analytical and electrochemical testing techniques jointly. This entails sophisticated apparatus and time-consuming sampling and analytical procedures off-line. Simple analytical tools for fast and reliable on-line detection and monitoring of MIC are lacking.