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FLUORINE FUNDAMENTALS
DuPont introduces short-chain fluorine-efficient products for producing surfactants that reduce the environmental impact of Class B fire fighting foam
Volume 23, No. 3

Performance rather than environmental impact continues to be the deciding factor when choosing between fluorinated versus fluorine-free fire fighting foam, said a DuPont Chemical executive introducing of a new line of fluorotelomer products.

Thomas H. Samples, Surface Protection Solutions global business manager for DuPont Chemical Solutions Enterprise, said the new Capstone products reduce to less than the current published limit of detection the bio-persistent compounds (or entities) that have plagued fluorine compounds in fire foam.

"It's pretty important to know that the performance of the foam is going to extinguish the fire in such a way that it will not reignite, better protecting the firefighters," Samples said. "The debate is about how much performance people are willing to give up in order to use fluorine-free alternatives."

Introduced in March, DuPont's Capstone products are available as fluorinated compounds for use in surfactants utilized to manufacture existing brands of fire fighting foams. Within the next 18 months, repellants and surfactants made from Capstone will also be offered for use in manufacturing home furnishings, leather goods, paper packaging and textiles.

"Our products are surfactants that are added to products like aqueous film forming foam (AFFF) to provide the film forming capabilities such as properties of extinguishment and that prevent burnback," Samples said.

No plans exist for DuPont to directly compete in the fire fighting foam market.

As the largest global manufacturer and supplier of fluorotelomers such as Capstone, DuPont plans to adapt its entire product line by year-end 2010 to utilize short-chain chemistry, a scientific process that reduces the potential for trace impurities in fluorinated compounds at the molecular level. Short chain molecules can not break down to PFOA in the environment.

Traditional fluorotelomer - based products involve substances where the fluorochemical portion is made up of a mixture of perfluorinated chain lengths that range in length from six to 16, with the majority containing eight. In DuPont short-chain fluorotelomers, the fluorochemical portion is made up of six or fewer perfluorinated carbons.

Despite the difference from traditional fluorotelomer products, DuPont Capstone is extremely compatible with other brands of fluorinated compounds being used in fire foams. Capstone will be listed on existing global regulatory clearances, including the United States (the Toxic Substances Control Act) and Europe (the European Inventory of Existing Commercial Substances).

However, in the U.K. and other parts of the globe, fluorine-free fire fighting foams are being touted as the solution to environmental issues linked to fluorinated compounds.

Dr. Stephen H. Korzeniowski, Surface Protection Solution technical manager for DuPont, said fluorine-free foams have some limits in burnback resistance when compared to current AFFF-based foams. This is particularly true in Class B fires such as large volume petroleum fires, foams without fluorine cannot deliver the performance possible with fluorine foam.

"The debate is really about how quickly you put the fire out and does it stay out?" he said. "Can you save the property and equipment and protect the firefighters? If you've got a refinery with gasoline or crude, how do you save those goods, what we refer to as value in use?"

Fluorine-free fire foams have environmental questions as well. While not as environmentally persistent as fluorinated compounds, the fluorine free foams have proven to be toxic to aquatic life, Korzeniowski said.

Fluorinated compounds, while effective as key ingredients in AFFF foams, have been an environmental flashpoint for foam makers since early this decade. One major foam manufacturer, 3M, abandoned production in 2000 due to the environmental persistence and bio-accumulation properties of perfluoro-octanyl sulfonate (PFOS), a specific compound resulting from a 3M process known as electro-chemical fluorination.

"With respect to the 3M product, there was a potential for biopersistence in the environment, meaning availability for bio-uptake and a long period of accumulation in biota," Korzeniowski said. "With the com-pounds we're introducing and the ones we've had on the market, the relative biopersistence is much, much lower. In fact, the uptake and clearance from organisms is very fast compared to the other alternatives."

As opposed to electro-chemical fluorination, DuPont and other companies making fluorinated compounds for use in fire foam utilize a process known as telomerization that is free of PFOS. 3M stopped production of PFOS-based foam agents in 2002. Regulations prevent the manufacture of new PFOS-based foam agents, but do not restrict the use of existing stocks. However, the European Union and Canada are proposing to ban the use of existing PFOS-based fire foam stocks within the next five years.

Prompting DuPont's move to short-chain chemistry in its fluorotelomer products is perfluorooctanoic acid (PFOA) found at trace levels as an unintended byproduct.

PFOA, also persistent in the environment, has been detected at low levels (average 5 ppb) in the blood of the general population. It has been studied extensively in an occupational setting where potential exposure can be significantly higher than that of the general population.

"DuPont believes the weight of evidence indicates that PFOA exposure does not pose a health risk to the general public," DuPont literature states. "To date, there are no human health effects known to be caused by PFOA, although study of the chemical continues."

As an alternative to abandoning fluorinated compounds in fire foams, significant effort is being made to develop technologies to recover fire water runoff and treat it to extract the spent fire fighting agents, Korzeniowski said. Another step is to reduce the use of fluorinated foam in training exercises as opposed to actual fire fighting.

Economic factors point to a healthy future for fluori-nated fire fighting foams, Samples said. First, a tremendous amount of infra structure is being built with regard to oil production and refineries. Likewise, a tremendous amount of infra structure is going up with regard to oil alternatives such as alcohol and bio fuels, Samples said.

"The polar solvents require alcohol resistant AFFF products," he said. "That infra structure growth is driving demand for the synthetic foams."

Also, regions such as Eastern Europe, the Middle East and China are moving to stricter standards in protecting their industrial facilities, driving demand for these products even higher, Samples said.

According to Korzeniowski, fluorinated fire fighting foams still have a strong chance at surviving increasingly stringent regulation, thanks to organizations such as the Fire Fighting Foam Coalition. Yet, there will be situations in the future where choosing fluorine free foam will be the preferred alternative.

"We need to be realistic," Korzeniowski said. "There is going to be a place for fluorine free chemicals. What has yet to be defined is what that place will be."

Samples said DuPont continues to put the end user of its fluorotelomer products first, considering the risks they face.

"We've heard loud and clear from industry that we need to deliver performance as well as environmental sustainability," he said. "That's our intent."

 
 

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