2, University College London, Adelaide, South Australia, Australia
Copper release is central in today’s marine antibiofouling coatings for its biocidal effect at the coating-water interface of ship’s exteriors. While copper is currently, broadly accepted, its release and accumulation causes pollution of marinas and harbors and deterioration to marine life. New green antibiofouling technologies are being researched, with our interest being a coating that works on never ending uptake-release cycles utilizing copper naturally present in the sea, thus constantly cyclically replenishing its antibiofouling function. Such coatings will be environmentally benign with no net release of copper and can also remediate copper-contaminated marinas and harbors. Our newly developed glutaraldehyde-crosslinked polyethyleneimine (GA-PEI) coating shows a high affinity and selectivity for copper, demonstrating a potential for solving the first step towards such a technology, the uptake. The coatings have shown to efficiently and selectively scavenge large quantities of copper from both artificial and real seawater.1, 2
Any material submerged in seawater will be rapidly conditioned by a polysaccharide film. Copper binding will compete with organic ligands which may limit the performance of the coatings. In this study, the effect of adsorbed seawater-relevant polysaccharides (i.e., carrageenan, sodium alginate, agarose and competing ligand EDTA) on copper binding performance of our polymer films was investigated in an artificial-seawater model system.3 Advanced analytical techniques were used, including grazing incidence X-ray absorption near edge spectroscopy, Time-of-flight secondary ion mass spectroscopy, X-ray photoelectron spectroscopy and quartz crystal microbalance with dissipation monitoring. Results revealed that in seawater a swollen polysaccharide layer allowed unhindered transport of copper into the PEI layer. Our coating outcompeted EDTA, and the spatial distribution of copper species was determined with nanometer precision. The results are highly relevant for copper extraction at low concentrations in complex natural environments as well as strongly suggest the further development of GA-PEI coatings towards advanced marine applications.
Keywords: Characterization of polymers, Copper-chelation, Environmental remediation, polyethyleneimine
1. J. B. Lindén, M. Larsson, B. R. Coad, W. M. Skinner and M. Nydén, RSC Advances, 2014, 4, 25063-25066.
2. J. B. Lindén, M. Larsson, S. Kaur, W. M. Skinner, S. J. Miklavcic, T. Nann, I. M. Kempson and M. Nydén, RSC Advances, 2015, 5, 51883-51890.
3. S. Kaur, I. M. Kempson, J. B. Lindén, M. Larsson and M. Nydén, Biofouling, 2017, 1-11.