NON-TOXIC COATED STRUCTURED FILTERS: A NON-BIOCIDE RELEASE STRATEGY FOR BIOFOULING CONTROL DR. ELISABETE R. SILVA OLGA FERREIRA ( PhD STUDENT) 2ND INTERNATIONAL ELECTRONIC CONFERENCE ON WATER SCIENCES (ECWS-2) 16-30 NOVEMBER, 2017
Biofouling Biological fouling: an spontaneous colonization by a diversity of micro/macroorganisms on submerged surfaces. Adapted from Nurioglu et al., 2015 and Almeida et al., 2007 2
Biofouling Burden! Water contamination (freshwater/seawater) by biofouling attach on industrial surfaces causes serious Environmental penalties penalties on several applications: such as water Economic impacts circuits, desalination systems, marine transport. Health problems 3
Biofouling Burden! Invasive species • Harmful pathogens • into water in fluid transport systems • Maintainance costs (Biocorrosion can affect up to 20%) • Fuel consumption increases for operation conditions maintainance • Gas emissions increases • Drag increase on ships hulls (40%) • Pressure drop increases in water flow industrial circuits 4
Anti-Biofouling Strategies Conventional antifouling strategies for biofouling mitigation are mostly based on the releasing of toxic agents! Top Coat Antifouling Layer BPR EU Regulation Nº528/2012 Is limiting the available antifouling agents SEVERE RESTRICTIONS! NEW SOLUTIONS ARE SOUGHT! 5
Booster Agents – Less Toxic? ECONEA Activity against hard-shelled and soft- bodied invertebrate animal fouling organisms Unknown future ecotoxicity/accumulation effects 6
Eco-friendly Solution Chemical immobilisation of bioactive agents Top Coat Layer Top Coat Layer “A goal properly set is halfway reached ” Zig Ziglar lar 1926 26-20 2012 7
Eco-friendly solution Biocides Functionalisation (1 st step) E. R. Silva, O. Ferreira, J. C. M. Bordado Patent Application, WO 2016/093719 A1 OCN-R-NCO OCN-R-NHC=O NH NCO Function N Econea biocide Conversions higher than 95% were achieved. 8
After functionalisation 0.40 Econea-R-N=C=O 0.35 Econea O=C=N-R-NHC=O 0.30 N-R Absorbance (a.u.) 0.25 (Econea) 0.20 0.15 R-N=C=O R-N=C=O -C=O 0.10 0.05 0.00 3.550 3.050 2.550 2.050 1.550 1.050 550 Wavenumber (cm -1 ) FTIR spectra confirmed the functionalisation reaction effectiveness 9
Eco-friendly Solution Immobilisation v ia Urethane linkage (as example) (2 nd step) A backbone based resin with OH functionality OCNH -R-NHC=O O OH OCNH -R-NHC=O N No biocidal agent release from the coating - preventing the contamination of the surrounded environment! 10
BIOACTIVITY ASSESSMENT Well Diffusion Method for Econea-NCO Econea Staphylococcus aureus DMSO Coating Other Other tested Econea-NCO coatings biocides without bioactivity Vancomycin Reference Coating Coating Econea Functionalization of the biocidal agent did not Econea affect its bioactivity. (Positive control) Coatings with immobilized biocide are bioactive. Promising result! 11
PROOF-OF-CONCEPT 1. Simulated tests in an artificial seawater aquarium Silicone based Polyurethane based formulations (A) formulations (B). 7B 8A 8B 7A 7- With immobilised Econea-NCO 8- Reference coating without biocide Coated prototypes exposed for 12 months! Coatings with immobilised Econea show an improved antifouling behaviour. 12
PROOF-OF-CONCEPT 2. Real field tests- At relative Stationary conditions Photos gently provided by ENP, SA 45 Weeks (11 months submerged) A B Pontoon for field tests in Estaleiros Navais de Peniche (ENP), SA Coated prototypes, with silicone based formulations, exposed for about 11 months in Atlantic sea: (A) Econea-NCO and (B) Reference coating. 13
Coated Filters with Non-toxic Bioactive Coatings Microbial attack cause serious human health infections ( E.coli, S. aureus ) Transmission from fluid transport systems (e.g. water purification) Non-Toxic preventive actions are urgent! Silicone based coating with immobilized Econea (A) and Reference coating without biocide (B) A B Ceramic Monoliths (200 cpsi) Coated monolithic filters evidenced uniform polymeric layers and minimal increases of surface roughness. Adhesion tests are on-going: Cross cut and pull-off tests/others. 14
Antimicrobial Activity of Coated Filters Coated Monolith S. aureus MRSA Uncoated CIP 106760 strain Monolith An expected high inhibition growth effect for MRSA strain And a bacteriostatic behaviour was also observed!!! 15
Antimicrobial Activity of Coated Filters 6 MRSA (CIP 106760) Strain Absorbance, OD (620 nm) 5 Monolithic support Coated Monolith (SilM) 4 Coated Monolith (SilE-NCO-M) 3 Auspicious inhibition 2 effects! 1 0 0 1 2 3 4 5 6 7 8 Time (h) A complete growth inhibition with the coated monolithic with a silicone based coating containing tethered Econea (SilE-NCO-M). 16
CONCLUSIONS Econea biocide was successfully tethered in polymeric coatings. Promising antifouling behaviors, at simulated and real conditions, were obtained for silicone based coatings containing the tethered Econea. Auspicious antimicrobial and bacteriostatic behaviour was found for coated monolithic filters with the Econea/silicone based coating. The developed non-release biocidal coatings acting by contact, are able to avoid toxic agents releasing into the aqueous environment. This approach is presented as a promising environmental friendly and long-lasting antifouling/antimicrobial alternative strategy for the bio- decontamination of waterborne systems. 17
"It is the worst of times but it is the best of times because we still have a chance." Sylvia Earle, Oceanographer Elisabete R. Silva (ersilva@fc.ul.pt) http://intheochem.fc.ul.pt/newsite/envrem.html 18
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