Bidding Farewell to the Forever Chemicals

Article by Paul Stevenson CEng FIChemE

Paul Stevenson discusses options for remediation of PFAS contamination

THE casual observer could be forgiven for thinking that the prescient environmental and public health crisis due to PFAS contamination of drinking water has come like a bolt-from-the-blue; man-made species of PFAS have been discovered in watercourses at all corners of the planet, and they are found in the blood of almost every mammal on Earth.

Most had never heard of the problem until a very recent avalanche of media coverage and questions in the Houses of Parliament. In Australia, the problem of PFAS contamination arguably entered the public consciousness in 2017 when the ABC Four Corners television documentary exposed the public health crisis caused by the use of PFAS-containing fire-fighting foams at Royal Australian Air Force Bases Williamtown and Tindal. Many will also now know about the PFAS crisis from the 2019 Hollywood feature film Dark Waters, about the US environmental attorney Robert Bilott who spent many years – beginning in the late 90s, with the latest settlement coming only last year – taking DuPont to task for damage that was caused by PFAS.

It shouldn’t have taken TV or Hollywood to raise awareness. We, as chemical engineers, should really have been awake to the problem much sooner. Per- and polyfluoroalkyl substances (PFAS) do not naturally occur but have been synthesised by the chemical industry since the 1950s and continue to be manufactured in some jurisdictions to this day, despite them being known to have caused huge environmental contamination due to their enormous environmental persistence, and toxicity to humans, including causing rectal and testicular cancers, thyroid and kidney diseases, and delayed onset of puberty1.

PFAS are a class of chemical species that exhibit significant surface activity, and therefore have been used in manufacturing of well-known consumer products such as Teflon (PTFE), Scotchgard and Gore-Tex as well as stain repellents, coatings and printing inks, for instance. PFAS have been used in aqueous film forming foams (AFFFs) that were employed until very recently against Class-B flammable liquid fires, including in military and civil aviation – a significant source of contamination.

The past history of anthropogenic environmental contamination by PFAS is one of cognitive dissonance at best, and at worst of corporate nihilism (as described by the New York Times) – given that its toxicity to humans has been suspected since the 1950s, and widely accepted for the past two decades, and yet its use continues to this day. The present situation with respect to PFAS is one of rapid realisation of the threat to human health and a scramble for regulation, along with a litany of lawsuits, although products using PFAS are still being manufactured in some jurisdictions. The future of PFAS will largely depend upon chemical engineers, because it is our profession that has the skills to remediate the environmental damage that has been caused. This article will look at some options.

In 2019, the Environmental Business Journal estimated the market for the remediation of PFAS contamination in the US alone to be US$160bn.
The problem of PFAS contamination of the environment has been described as a multi-headed hydra because:

  • PFAS species are generally extremely toxic, and have been proven to cause many serious diseases in humans;
  • The characteristic fluorine-carbon bond that exists in all PFAS species (see Figure 1 for the chemical structure of PFOA) is very strong, meaning that they have enormous persistence in the body and in the environment and they are difficult to destroy. It is for this reason that PFAS are sometimes known as “forever chemicals”; and
  • PFAS species are highly-adsorptive to solid and fluid surfaces, meaning that they can be difficult to remove from such surfaces.
Figure 1: Chemical structure of Perfluorooctanoic acid (PFOA), often informally called ‘C8’, that exhibits 15 incredibly strong C-F bonds, which are nominally the strongest bonds in organic chemistry

Article by Paul Stevenson CEng FIChemE

Principal Engineer of Stevenson Process Technology

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