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Nature Imitated to Fight Fouling

Monday, July 2, 2012

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Inspired by one of nature’s own defense mechanisms, scientists at Johannes Gutenberg University Mainz (JGU) in Germany have discovered that tiny vanadium pentoxide nanoparticles can inhibit the growth of barnacles, bacteria, and algae on surfaces in contact with water, such as ship hulls, sea buoys, or offshore platforms.

A team of scientists working under Professor Dr. Wolfgang Tremel of the Institute of Inorganic Chemistry and Analytical Chemistry at JGU was inspired by certain enzymes found in brown and red algae that produce halogen compounds with a biocidal potential. It is assumed that these compounds are synthesized by the algae to protect them again microbial attack and predators. The chemists at JGU decided to mimic this process using vanadium pentoxide nanoparticles, a release from the university stated.

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Particles imitating a natural biocidal defense could help prevent fouling on ship hulls.

The university’s experiments showed that steel plates with a coating containing dispersed vanadium pentoxide particles could be exposed to seawater for weeks without the formation of deposits of barnacles, bacteria, or algae. In comparison, plates that were coated only with the ship’s normal paint 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 and more cost effective than the current coatings in use, according to the university’s release.

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 antibacterial effect, according to JGU. The required reactants are present in seawater.

The process has been demonstrated both under laboratory conditions and in natural seawater. According to the university, it has 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.

“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 substances used in the commercially available products,” explained Dr. Tremel. “Here we have an environmentally compatible component for a new generation of antifouling paints that employ the natural defense mechanism used by marine organisms.”

Ron Wever, the team’s Dutch cooperation partner from the University of Amsterdam, has been investigating such natural defense mechanisms for the last 15 years. He suggested adding the enzyme involved to antifouling paints. The chemists at JGU are no working together with Wever to develop vanadium pentoxide nanoparticles.

A research group at the Max Planck Institute for Chemistry in Mainz, headed by Dr. Klaus Peter Jochum, has been conducting experiments to determine whether the use of vanadium pentoxide might have a negative effect on the environment. Using a sensitive ICP mass spectrometer, the scientists determined the concentration of vanadium in various samples of seawater that had been exposed to the coated material for different lengths of time and found that levels were only slightly elevated above the normal average vanadium concentration in seawater.

More information is available from JGU.