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Non-toxic coated structured filters: a non-biocide release strategy for biofouling control
Elisabete Ribeiro Silva * , Olga Regina Ferreira *
1  Faculdade de Ciências, CQB/DQB, Universidade de Lisboa, Lisboa, Portugal
2  Instituto Superior Técnico, DEQ, CERENA, Universidade de Lisboa, Lisboa, Portugal


Authors: Olga Ferreira*, João Gomes, Maria J. Calhorda, Elisabete R. Silva*

Over two-thirds of Earth’s surface is covered by water, and its contamination with invasive aquatic organisms (biofouling on submerged surfaces) is an actual challenge. This bioburden, conventionally treated with the release of toxic agents into the surroundings of the contaminated surfaces, is associated with serious environmental and economic penalties, as well as health risks on several industrial applications (e.g. water purification, desalination units).

In this work, it was developed a new non-toxic alternative able to control this biofouling, by applying a novel immobilisation process (WO2016/093719 A1, 2016) for antifouling agents. Briefly, the immobilisation of biocidal agents (e.g. Econea) was performed by providing new functional biocides (e. g. Econea-NCO) capable of being tethered in polymeric coatings.

Bioactivity assessment of the developed antifouling systems suggested that the biocide properties were not significantly affected by the functionalization process. Econea biocide and its functional counterpart showed similar bioactivity against Staphylococcus. aureus, and similar Minimal Inhibitory Concentration (MIC).

Antifouling assessment of coated polymeric substrates with the most promising coatings (silicone marine based paint) containing the immobilized biocide, was carried out at near static conditions in Atlantic seawater (real field test) and in an artificial seawater aquarium. Auspicious antifouling performances were obtained. The coated substrates remained clean after being immersed in those aquatic environments for more than a year.

Furthermore, an ecotoxicity study of biocidal coatings following standards included in the EU hazard assessment of substances and European Eco-label was performed. In accordance with the European standards the coatings were classified as not harmful to the environment.

Structured filters supports (e.g. monoliths) were also successful coated with the best biocidal coatings. Uniform polymeric films were obtained, and adhesion tests are on-going. The next step of this work is to develop an experimental method to confirm the effectiveness of the coated supported filter structures against biofouling at simulated operational conditions (e.g. water circuits). This approach is presented as an alternative non-toxic and long-lasting antifouling strategy.


Support for this work was provided by FCT through UID/MULTI/00612/2013 and Pest-OE/QUI/UI0612/2013. O. Ferreira and Dr. E. R. Silva are also grateful for the financial support from FCT, PhD Grant PD/BD/128370/2017 and Post-Doc fellowship SFRH/BPD/88135/2012, respectively. The authors also thank the support of HEMPEL A/S and P. Rijo for the work collaboration.

Keywords: biofouling, antifouling coated filters, non-toxic strategy, immobilized biocides, water decontamination
Comments on this paper
Joanna Wyczarska-Kokot
Biocidal coatings in swimming pools?
Dear authors,
Very interesting job!
I wonder how much your research could be applied to swimming pools. Would it be possible to cover the walls of swimming pools proposed by you with biocidal coatings? The problem is that there are thin layers (with bacteria and protozoa potentially pathogenic), which are difficult to remove even with strong detergents. It may be a good idea to expand your interests and research for swimming pool technology?

Thank you
Elisabete Silva
Thank you for your interest in our work.

You are completely correct, it is quite possible to use the process for the immobilization of antimicrobial/antifouling agents in others polymeric coatings, including the ones suitable for swimming pools walls protection or even filter system. This would lead to a good collaborative project.

We can achieve the technology until the proof-of-concept since minor damages occur in the major coatings properties (adhesion, etc.). But to provide a final commercial paint/coating we always need the collaboration of a coatings producer for the final formulations optimization, this because the coatings formulations are confidential from suppliers, which does not allow us to proceed with final adjustments.

Thank you very much for the good suggestions!

Kind Regards
Joanna Wyczarska-Kokot
Thank you for your detailed explanation. I hope that this type of coating could be tested successfully in an experimental pool circuit. Good luck in further research.

Kind Regards
Elisabete Silva
Thank you very much. I'll try to find a way to test it in a pool circuit.

Kind Regards