Anant R. Sontake, Sameer M.Wagh
Chemical Engineering and Science. 2014, 2(1), 11-14DOI:
Abstract: Aqueous film-forming foams (AFFFs) are among the most popular fire-fighting foams used in liquid fuel fires because of their film forming and fast knock down property. One key ingredient of AFFFs, the fluorocarbon surfactant i.e. perfluorooctane sulfonate (PFOS) which is used to reduce surface tension and positive spreading coefficient, is toxic to aquatic life and is a persistent chemical that accumulates in the blood of humans and other animals. Surfactants are not found naturally in the environment and are man-made. In the year 2000 unexpectedly announcement of phasing out fluorocarbon surfactant’s manufacturing and its storage which effected a number of product lines, including the firefighting foams. Internationally the manufacturing and release of PFOS to the environment will be suspended by 2015. New fluorosurfactants have been introduced into the market with reformulation and used to form aqueous fire-fighting foam concentrates. The toxicity of the new fluorosurfactants and their persistence in the environment are not well established and still are under investigation. Their presence in the future market is unsure. The continuous research and development to find out the substitute for perfluorooctane sulfonate derivative (C8) has brought two choices i.e. Fluorine-free foams or Fluorotelomer (C6)-based Foams. These foams which may fulfill requirement of different international standards of fire fighting but still contain small amounts of fluorochemicals and are thus not truly fluorine-free. There is every possibility that even after 2015 new regulation may come in to effect to restrict the use of these new formulations (C6) of fire fighting foam. Therefore, the fire-fighting industry has an urgent need for new, environmental friendly foaming agents and foam stabilizers to replace fluorosurfactants in aqueous fire-fighting foams with enhanced drain time, low bubble coarsening, and faster knockdown and excellent burn back resistance properties.