Multifunctional Inhibitor Mixture for Reducing Bacteria Growth and Corrosion on Marine Grade Steel

High strength steel in marine environments suffers from severe corrosion susceptibility and the presence of bacteria can exacerbate the effect, accelerating degradation via microbiologically influenced corrosion (MIC). Here we propose a novel approach to MIC inhibition by designing a system capable of limiting the effects of both bacteria growth and corrosion. The combination of a newly synthesised compound, cetrimonium 4-hydroxycinnamate, with lanthanum 4-hydroxycinnamate was the only system tested to date that could both inhibit abiotic corrosion in artificial seawater and minimise bacteria consortium densities over an exposure period of 24 hours.

The electrochemical data for the La+Cet mixture demonstrated the significant inhibition of both abiotic corrosion to a level similar to La(4OHCin)₃, as well as the ability to reduce bacteria densities of single strains and a consortium. This is unlike the La+CetNal mixture which accelerated abiotic corrosion and the La+IMI which had an insignificant effect on microbial densities (Catubig et al. 2020).

A compatible mixture of ionic inhibitors was achieved by using the same cinnamate anion.

This mixture of Cet-4OHCin and La(4OHCin)₃ demonstrated significant abiotic corrosion inhibition and bacteria density reductions, making it a strong candidate as an MIC inhibitor system for 80HLES.

The Cet-4OHCin compound and its mixture with La(4OHCin)₃ retained relatively low sensitivity towards skin and intestinal cells, making it a safer and more attractive alternative than other more hazardous corrosion inhibitor materials.