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Thursday, 19 September 2019
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Raw materials & technologies, Applications, Protective & Marine coatings

Fight against algaes with marine coatings – next round with bactericidal nano-agents

Wednesday, 4 July 2012

One more solution found out to stop the growth of barnacles, algeas and bacteria at ship bodies: It mimics natural enzymes.

a) Biofouling at a boat hull; b) knotted wrack, Ascophyllum nodosum; c) Mode of action of bioinspired under water paints: Like the natural enzyme vanadium bromoperoxidase vanadium pentoxid nanoparticles act as a catalyst for the formation of hypobromous acid from bromide ions (contained in sea water) and small amounts of hydrogen peroxide that are formed upon exposure to sun light.Source: Tremel research group, JGU
a) Biofouling at a boat hull; b) knotted wrack, Ascophyllum nodosum; c) Mode of action of bioinspired under water paints: Like the natural enzyme v...

Vanadium pentoxide nanoparticles mimic natural enzymes and inhibit surface build-up of algae and bacteria.

Ship hulls without organisms

Vanadium pentoxide seems to be the solution to inhibit the growth of non-welcomed attachements on ship hulls. Scientists at Johannes Gutenberg University Mainz (JGU) in Germany showed that steel plates to which a coating containing dispersed vanadium pentoxide particles had been applied could be exposed to seawater for weeks without the formation of deposits of barnacles, bacteria, and algae.

 Interesting, especially in comparison with the ship's normal painted plates. They exhibited massive fouling after exposure to seawater for the same period of time. The discovery could lead to the development of new protective, antifouling coatings and paints that are less damaging to the environment than the ship coatings currently used.

Brown and red algae are the natural prototype for the reseach

The biocidal potential can be found in halogene compounds which certain enzymes found in brown and red algae produce. The scientists assume that these are synthesised by the algae to protect them against microbial attack and predators.

Vanadium pentoxide functions as a catalyst so that hydrogen peroxide and bromide combine to form small quantities of hypobromous acid, which is highly toxic to many microorganisms and has a pronounced antibacterial effect. The required reactants are present in seawater: This already contains bromide ions, while small quantities of hydrogen peroxide are formed when it is exposed to sunlight.

"Vanadium pentoxide nanoparticles, due to their poor solubility and the fact that they are embedded in the coating, are considerably less toxic to marine life than are the tin- and copper-based active substances used in the commercially available products," explains Wolfgang Tremel, Professor at JGU.

Minimising environmental impact with the new foundings

The process has been demonstrated both under laboratory conditions and in natural seawater. It has only very minimal consequences for the environment because the effect is restricted to micro-surfaces. The metallic oxide is particularly potent when it is present in the form of nanoparticles because then, due to the larger surface area, there is an enhanced catalytic effect.

Decrease of costs for ship repairs

Additional costs for the marine industry are implied by the attachement of seawater organisms.  Due to repaintings, and repairs the need for more fuel is as well countable. This also leads to increased CO2 emissions.

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