
Thesis Format
Integrated Article
Degree
Master of Science
Program
Biology
Supervisor
Tai, Vera
2nd Supervisor
Hedberg, Yolanda S.
Co-Supervisor
Abstract
Microbial-influenced corrosion (MIC) has been reported to cause structural damage in pipelines. Epoxy coats can mitigate corrosion but delaminate over time. N-heterocyclic carbenes (NHC) can potentially increase adhesion between epoxy coats and metals. This research investigated the effectiveness of NHC-enhanced epoxy-coated mild steel against MIC. Initial experiments evaluated various media to determine conditions that promoted mild steel corrosion when exposed to Escherichia coli ATCC 25922. E. coli in M9 medium increased corrosion, while in LB medium, corrosion was inhibited. In subsequent experiments, two types of epoxy-coated and epoxy-NHC-coated mild steel were exposed to E. coli in M9 and LB media. Measurements of dissolved iron, oxidation levels, and surface observations showed that E. coli increased corrosion, but the addition of NHC did not reduce MIC. NHC may prevent corrosion under less corrosive experimental conditions, with a different type of epoxy coating, or in the presence of more environmentally relevant bacteria.
Summary for Lay Audience
Steel is essential in our everyday lives, used in everything from kitchen appliances and cars to pipelines and powerplants. However, its primary component, iron, is naturally prone to corrosion, which can be accelerated by microorganisms. Corrosion not only leads to significant economic losses but also poses safety risks. To combat this, industries often coat steel with a corrosion-resistant coat like epoxy. These epoxy coats act as a physical barrier, protecting the metal underneath. However, epoxy coats can become damaged and delaminate (peel off) over time, allowing oxygen, water, and microorganisms to get underneath and cause corrosion. To address this issue, researchers are developing N-heterocyclic carbenes (NHCs) as primers for epoxy coats to enhance their adhesion and durability. NHCs are special compounds that can bond strongly with metal surfaces and could potentially also link with epoxy to act like a glue to prevent the delamination of epoxy layers and corrosion. This research investigates whether epoxy coats enhanced with NHCs can effectively protect against corrosion caused by the model bacterium E. coli. Mild steel exposed to E. coli increased corrosion compared to steel that was exposed to growth medium alone. However, the NHC did not improve the epoxy’s adhesion to the steel surface or mitigate E. coli-induced corrosion. By understanding how NHCs improve epoxy coats, this research could lead to longer-lasting, more reliable protection for steel structures. This has the potential to save costs and improve safety in industries where steel is a critical material.
Recommended Citation
Nguyen, Richard, "Microbial corrosion of N-heterocyclic carbene-enhanced coated mild steel" (2024). Electronic Thesis and Dissertation Repository. 10587.
https://ir.lib.uwo.ca/etd/10587