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Old 06-02-2017, 17:51   #1
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Antifouling: Cerium dioxide

Media release of 2 February 2017, from: https://www.eurekalert.org/pub_relea...-dme020217.php

Chemists at Johannes Gutenberg University Mainz (JGU) have developed a method that reliably hinders hazardous seawater fouling and is effective, affordable, and easy on the environment. Fouling can occur, for example, as the result of the growth of bacteria, algae, or mollusks in harbor facilities, on boat hulls, and aquaculture netting. The resultant damage and consequential costs can be significant. It is estimated that these are equivalent to 200 billion dollars annually in the shipping industry alone. Protective coatings applied to vessels usually contain copper-based biocides. These have the disadvantage that they harm the environment while resistance to them can also develop. In order to find an alternative, the Mainz-based research team of Professor Wolfgang Tremel decided to simulate a defense mechanism employed by algae and established that cerium dioxide nanoparticles can effectively prevent fouling. This discovery could contribute towards the production of new protective coatings that are much less environmentally harmful than the hull coatings in use to date.
Marine algae utilize secondary metabolic products in order to provide themselves with a form of chemical defense against micro-organisms and predators. These halogenated secondary metabolites specifically prevent bacterial biofilms, other algae, and even barnacles becoming attached to and developing on larger formations of algae, sponges, and other creatures. Halogenated compounds produced by the red seaweed Delisea pulchra, for instance, inhibit bacterial fouling but are neither toxic nor growth-retarding. Instead, they scupper what is known as quorum sensing, i.e, a system used by bacteria to communicate with the help of messenger substances that results in the formation of biofilms. The structures of the halogenated compounds synthesized by seaweeds are similar to those of these substances so that they cause a blockade of the bacterial receptors and suppress the switchover of bacterial gene regulation to biofilm formation. This form of interference with bacterial gene regulation is also of pharmaceutical interest as it is known that pathogenic bacteria can protect themselves against attack by the immune system and the effect of antibiotics by forming biofilms, for instance on the epithelium of the respiratory system.

This natural defense process has been mimicked by the Mainz-based team of chemists using nanoparticles of cerium dioxide. "Field tests have shown that cerium dioxide is an ecologically acceptable alternative to cuprite, a substance that is used as a biocide together with copper thiocyanate and copper pyridine at concentrations of up to 50 percent in anti-fouling coatings," explained Professor Wolfgang Tremel of JGU's Institute of Inorganic Chemistry and Analytical Chemistry. But such copper compounds are toxic and accumulate in the environment. This is why some countries, such as Canada and Denmark, have imposed strict limitations on the use of copper-based anti-fouling coatings.

A cost-effective and environmentally-friendly alternative to cupriferous biocides:
"All modern catalytic converters in vehicles use cerium dioxide. It is non-toxic and chemically extremely stable," added Karoline Herget, who wrote her doctoral thesis on the project. She is convinced that cerium dioxide is a practical and cost-effective alternative to conventional biocides.
Cerium dioxide is an oxide of the rare earth element cerium and a by-product of the process of extraction of rare earth metals. Despite belonging to the family of rare earth elements, cerium itself is not particularly scarce. Its cost is thus comparable with that of cuprite (copper(I) oxide), although it is effective in far lower quantities. "What we have here is an environmentally compatible component of a new generation of anti-fouling coatings that simulate the natural defense systems employed by marine organisms. What is important is that it is effective not only under laboratory conditions but also when actually used in the aquatic environment," Herget concluded. Steel panels with cerium oxide coatings can be exposed to seawater for weeks on end without becoming covered by bacteria, algae, mollusks, or barnacles. Reference samples with conventional water-based coatings develop massive fouling over the same time period.
For more, see:


http://onlinelibrary.wiley.com/doi/10.1002/adma.201603823/abstract
http://www.uni-mainz.de/presse/15482_ENG_HTML.php

https://en.wikipedia.org/wiki/Cerium(IV)_oxide

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Old 06-02-2017, 18:20   #2
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Re: Antifouling: Cerium dioxide

How long is "weeks one end"?

5 weeks, 250 weeks?
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Old 06-02-2017, 19:40   #3
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Re: Antifouling: Cerium dioxide

Awesome, it lasts weeks!
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Old 06-02-2017, 21:34   #4
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Re: Antifouling: Cerium dioxide

Sneer if you will, but I've got my fingers crossed. Hope like hell that it actually works!

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Old 06-02-2017, 22:36   #5
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Re: Antifouling: Cerium dioxide

The 'weeks on end' text in the press release is because the researchers only ran their experiment for 52 days. They were confident that their experiment worked. And their research paper passed peer review.

The experiment included commercial antifouling paint both soft and hard, and compared plates coated with commercial antifouling to plates coated with with nano-sized grains of CeO2 added.


If you do not have access to the Wiley publication (Advanced Materials), you can see some more at:


https://phys.org/news/2017-02-defens...y-inhibit.html


That was experimental work to prove the principle. No researcher is going to sit on their hands and watch an experiment for 2 or 3 years before publishing.


Next step may be up to a commercial antifouling paint manufacturer, with a license from BASF.


A navy that has a large fleet of submarines likely will move earlier.
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Old 07-02-2017, 06:03   #6
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Re: Antifouling: Cerium dioxide

If I had a dollar for every supposed anti fouling magic bullet that has come down the pike over the last twenty years...
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Old 07-02-2017, 06:16   #7
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Re: Antifouling: Cerium dioxide

Can it be mixed with cayenne pepper?

Seriously, if it's not tested for three or more years, it can't be compared to conventional bottom paint. Post back in three years.
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Old 07-02-2017, 06:34   #8
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Re: Antifouling: Cerium dioxide

Quote:
Originally Posted by Alan Mighty View Post
The 'weeks on end' text in the press release is because the researchers only ran their experiment for 52 days. They were confident that their experiment worked. And their research paper passed peer review.

The experiment included commercial antifouling paint both soft and hard, and compared plates coated with commercial antifouling to plates coated with with nano-sized grains of CeO2 added.


If you do not have access to the Wiley publication (Advanced Materials), you can see some more at:


https://phys.org/news/2017-02-defens...y-inhibit.html


That was experimental work to prove the principle. No researcher is going to sit on their hands and watch an experiment for 2 or 3 years before publishing.


Next step may be up to a commercial antifouling paint manufacturer, with a license from BASF.


A navy that has a large fleet of submarines likely will move earlier.
Current submarines is service use a ablative cuprous oxide - works well enough but I think certification of MIL-PRF-24647 requires more time. USN isn't going to use submarines as testing beds.
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Old 07-02-2017, 06:36   #9
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Re: Antifouling: Cerium dioxide

I remember the whaling ship that used new zinc plates instead of copper. And halfway through its 2-year voyage it had no protection because the zinc was gone.
I hope this promising experiment pans out and becomes a viable non-toxic but I won't risk my vessel to promising technology.
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Old 07-02-2017, 06:38   #10
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Re: Antifouling: Cerium dioxide

Wait until you see some independent testing and then consider the product.
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Old 07-02-2017, 06:59   #11
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Re: Antifouling: Cerium dioxide

I'm not jumping on any new af till it has been around at least 10 years
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Old 27-05-2017, 19:01   #12
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Re: Antifouling: Cerium dioxide

Any ideas where to locate a gallon or two?
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