ZEOLITE-SUPPORTED SILVER NANOPARTICLES AS BIOCIDAL ADDITIVE FOR ELASTOMERIC COATING FORMULATIONS

A.M. PEREYRA; G.E. MACHADO; V. ROSATO; M.S. MORENO; M. SOARES LUTTERBACH; E. BASALDELLA

Congreso; International Symposium on Applied Microbiology and Molecular Biology in Oil Systems (ISMOS7); 2019

The presence of microorganisms on exposed surfaces leads to the spread of microbiological contamination. At present, the use of antimicrobial coatings is a methodology employed to provide an effective control of microbiological growth. Microbial adhesion begins when the microorganisms adhere to a surface embedded in a gelatinous matrix called biofilm, which promotes a significant modification of the interface and generally increases the substrate deterioration. The development of coating systems with antimicrobial properties based on film-forming materials suitable for particular protection of diverse substrates is nowadays an industrial requirement. For example, the outcome of reliable methods for the prevention and control of microbiologically influenced corrosion is one of the main achievements still pending for research and applied engineering. This work introduces an entirely new approach through the use of zeolite/nanoparticle composites as biocidal additive for coating formulations. The zeolite network would stabilize the delivery of active silver nanoparticles at a nanometric level facilitating the optimization of their dosage. Silver nanoparticles dispersed onto micrometer-sized crystals of A-type zeolite were prepared by reduction methods applied to a Ag-exchanged zeolite. TEM, XRD and UV-Vis analyses confirmed the presence of rounded crystalline silver nanoparticles, homogeneously dispersed on the outer surface of the zeolite crystals: Ag0 and Ag2O nanoparticles coexisted with noncrystalline clusters and silver cations hosted inside the porous structure. The microbiological activity of elastomeric coatings formulated with the synthesized zeolite/silver nanoparticles, measured in terms of inhibition halo development, clearly indicated that the inhibition of Trichoderma sp. growth was similar to that obtained by adding a commercial biocide based on isothiazolinones. The chemical nature, size and size distribution of the nanoparticles were the main factors affecting the biocidal action of the prepared coatings. On this basis, the coatings formulated with the silver composite could be considered suitable to prevent microorganism growth and its consequential production of metabolic substances responsible for sustrate deterioration. Also, the supported silver nanoparticles could be considered for the substitution of many of the organic biocides, which according to environmental regulations should be replaced by low-toxicity and environmentally friendly alternatives.