Non-stick cookware is coated with the fluoropolymer Teflon (PTFE), which was first used for seals resistant to uranium hexafluoride during the Second World War and applied to commercial bread- and cookie-making by DuPont in 1951. When a pan is overheated beyond roughly 350 °C the coating breaks down and releases perfluorooctanoic acid (PFOA); together with the related PFOS, these compounds are also used as surfactants, fire retardants and lubricants, and because their strong C–F bonds resist biological degradation, oxidation and reduction they are now found in air, water, soil, human livers and wildlife. Exposure is linked to polymer fume fever, tumours in rodents, cancer and thyroid disease in humans and contamination of drinking water, and around thirty other perfluorinated compounds have been found in affected waters.
Adsorption on materials such as boehmite, alumina, activated carbon, carbon nanotubes and activated sludge is the usual removal method, but these adsorbents are not very efficient. The article then describes a polymer developed by William Dichtel's group at Northwestern University, made from cornstarch-derived beta-cyclodextrin and fluorine-rich decafluorobiphenyl, which acts as a 'PFC magnet', captures about 95 per cent of PFOA from water (against roughly half for activated carbon), still works when other common chemicals are present and can be regenerated by washing with methanol. The group is now trying to bring the material to market so that households and businesses could one day filter their own water.
