Antibacterial and antifungal epoxy coatings with improved aesthetic properties

S. MARINO; S. MORENO; M. SOARES LUTTERBACH; M. GONZALEZ; A. M. PEREYRA; E.I. BASALDELLA

Edimburgo

Congreso; ISMOS 9, 9TH INTERNATIONAL SYMPOSIUM ON APPLIED MICROBIOLOGY AND MOLECULAR BIOLOGY IN OIL SYSTEMS; 2023

Universidad de Edimburgo

Protective coatings with a "barrier effect" such as epoxy paints are often used, accompanied by cathodic protection, in pipelines and tanks to avoid corrosion. The incorporation into these coating types of a synthetic zeolite containing biocidal cations such as Ag+ inhibits the biofilm formation and, consequently, the microbiologically influenced corrosion. However, coatings with Ag+-exchanged zeolite depict a darkening of the epoxy film. This effect is more pronounced with time, affecting the visual appearance of the film.In this context, the aim of this work was to formulate epoxy coatings modified with increased levels of Zn2+ in Ag+-exchanged zeolite A, that provide adequate biocidal performance without affecting the aesthetic properties of the film. Factors such as Ag and Zn concentrations, the sequence of cation addition and the influence of ammonium as a complexing agent were considered in the ion exchange procedure. Zn2+/Ag+-exchanged zeolite A powder showed a white color for zinc concentration above 4% in samples containing 25% of silver cations. The zinc cations position in the framework could avoid the migration of silver species (Ag+ cations, Agmn+ clusters) hosted in the zeolitic cages and its consequent photo-oxidation. Coatings formulated with higher levels of Zn2+ in Ag+-exchanged zeolite and exposed to environmental conditions for five years did not show darkening and maintain the biocidal capacity. These results are promising for applications that use these zeolites with high rehydration capacity, which simultaneously require long lasting biocidal activity while preserving aesthetic properties.