Nanotech Coatings Found to Protect Ships from Barnacles

(CMTS.gov)

Chemists and molecular biologists in Germany and the Netherlands have tested coatings with vanadium pentoxide nanoparticles as an alternative to tin- and copper-based substances that prevent the build-up of marine organisms on ships’ hulls. The team led by Wolfgang Tremel of Johannes Gutenberg University in Mainz, Germany reported their findings online this week in the journal Nature Nanotechnology (paid subscription required).

The researchers say the fouling of ships’ hulls from algae, mussels, and barnacles costs the global shipping industry some $200 billion per year. An underwater boat hull can be completely covered and overgrown with organisms within a few months. The team cites the marine insurer Lloyd’s that says the accumulation of marine organisms on ships can increase fuel consumption by 28 percent and add some 250 million tons of CO2 to the atmosphere each year.

Current methods of combating marine organisms include paints made from tin- and copper-based compounds. In addition to preventing the build-up of barnacles and other organisms, however, these compounds are toxic to other other marine life from metal leaching. Tremel’s team therefore sought a solution that would prevent the accumulation of organisms, with a minimum of environmental damage.

The researchers aimed at finding a material that could mimic the enzymes found in brown and red algae, which produce compounds to protect the algae against microbial attack and predators. Using this approach, they tested vanadium pentoxide (V2O5) nanoparticles, which function as a catalyst to enable hydrogen peroxide and bromide to form small quantities of hypobromous acid.

The reactants needed for the catalysis to occur are already present in seawater, including bromide ions, with small quantities of hydrogen peroxide that are formed when exposed to sunlight. The resulting hypobromous acid is toxic to many microorganisms and has a pronounced antibacterial effect.

Tremel’s team tested the coatings made with vanadium pentoxide nanoparticles in the lab and in an ocean lagoon off the coast of Portugal. In the ocean tests, the team applied commercially available antifouling paint to two stainless steel plates, 2 cm square, with one plate also having the vanadium pentoxide coating. The plates were attached to a boat docked in the lagoon. After 60 days, the plate without vanadium pentoxide nanoparticles showed heavy accumulations, while the plate with the vanadium pentoxide coating did not.

Co-author Klaus Peter Jochum of the Max Planck Institute for Chemistry in Mainz tested the potential environmental impacts of the vanadium pentoxide nanoparticle coatings. Using mass spectrometer readings, Jochum and colleagues tested samples of seawater that had been exposed to the coated material for different lengths of time. They found levels were only slightly elevated above the normal concentration of vanadium in seawater, indicating that only tiny amounts of vanadium migrate from the coating into seawater.

Tremel attributes the little migration of vanadium from the coating to the low solubility of the nanoparticles, and their embedded status in the coating. “Here we have an environmentally-compatible component for a new generation of antifouling paints,” concludes Tremel, “that employ the natural defense mechanism used by marine organisms.”

Read more:

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• Sensitive Underwater Microphone Works at All Depths
• Antibody-Based Biosensor Aids Environmental Cleanups
• Public-Private Research Helps Oyster Growers Meet FDA Regs
• Consortium to Study Ocean Potential for Carbon Storage

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