New Technology with the Potential to Eliminate PFAS and PFOAs from Water Sources
The challenge of PFAS contamination (sometimes publicly known as PFOS, PFOA, or GenX contamination) of drinking water and its risk to public health is featured in a leading Hollywood film being released this year.
PFAS exposure can be dangerous to humans, possibly causing liver damage, kidney cancer, and developmental issues in children. Over the years, the substance can build up in animals and humans, which heightens the risk.
PFA Substances: PFAS, or Per- and polyfluoroalkyl substances are what the US Food and Drug Administration has termed ‘Forever Chemicals’ because of their endurance in the human body. They were the preferred choice among consumer product chemists because of their hydrophobic chains, which enable the material to produce a non-stick coating and move water away. The substance can be discovered in the cooking non-stick pans, office furniture, and fast food packaging. It is also popular in firefighting foams, which has resulted in extensive contamination of water sources where these foams are utilized. There has not been much planning on what to do with the contaminant, even though there are methods to collect PFAS. Chemical engineers are producing several techniques to totally destroy PFAS that are collected, but they need off-site processes which either require burying the conjoined adsorbent or PFAS material as a new form of permanent waste or are highly energy-intensive. Temperatures of 1000 °C (~1800 °F) are needed for the latter method, and not many adsorbents utilized to collect the chemical can survive that degree of heat. The cost to the environment is still high in both of the methods.
Metal Organic Frameworks - Enter MOFs: Metal Organic Frameworks are crystalline 3D structures with an extraordinary internal surface area that transfers into an incredible ability to absorb molecules. A method to produce defects in MOFs made at Rice University has already demonstrated that the materials can absorb over two times more than the industrial standard, activated carbon.
Destruction of PFAS: The first MOF company, framergy, Inc., was funded by the US Environmental Protection Agency (EPA), under the Small Business Innovation Research (SBIR) program, in late 2019 to investigate PFAS destruction. In collaboration with Texas A&M University, the research looks at how PFAS are captured by MOFs. The MOF and guest PFAS molecules are then subjected to ultraviolet light.
Scientists at framergy are utilizing ARYSORB™ T125, a titanium MOF that is structurally similar to the UiO-66 variety employed by the Rice scientists. ARYSORB™ T125 is based on MIL-125-NH2, which was first invented in 2008 by Christian Serre and Gerard Ferey of the Centre National de la Recherche Scientifique (CNRS). In ARYSORB™ T125, titanium oxo clusters are periodically arranged and divided through the use of organic linkers, which results in a large and highly accessible surface area. The titanium nodes can then perform as a photocatalyst on the guest PFAS molecule, something impossible in UiO-66. This material is exclusively licensed to framergy, along with all alternative titanium-based MOFs known, by CNRS, and is available at commercial scale from the organization and at Strem.com.
ARYSORB™ T125: Destruction tests were carried out with 500 ppm perfluorooctane sulfonate (PFOS) in an aqueous solution with 1% triethanolamine as a sacrificial reductant. Conversion of PFOS to less harmful organic material was visibly confirmed by Fluorine-19 nuclear magnetic resonance spectroscopy, after which an Agilent liquid-chromatography-mass spectrometer showed three distinct peaks for C8 down to C3 compounds with different fluoride content. This definitely proved that PFAS species originating in water can be collected and degraded by ARYSORB™ T125 into smaller substances that are less dangerous, with the use of readily available UV light.
Vapor Point Leads Scale up and Additive Manufacturing: Following the proof-of-concept studies, the candidate MOFs were scaled up by Vapor Point and water remediation reactors were manufactured by 3D-Printing. The novel additive manufacturing practices followed by Vapor Point has led the team to quickly excel through the prototyping steps to gather this technology’s first PFAS breakdown (total mineralization) results. These scaled up MOFs have been the first group to photocatalytically degrade and mineralize PFAS; although adsorptive removal of PFAS has been shown in the past, none of the MOFs published to date could initiate reductive reactions to breakdown and mineralize the adsorbed PFAS within their framework until this study.
The Vapor Point and framergy team is vigorously scaling the technology for commercialization through the EPA’s SBIR program where PFAS are being focused on by the agency at the same time through, "the most comprehensive cross-agency action plan for a chemical of concern ever undertaken by the agency," as stated by Andrew Wheeler, Director.
About the Author
Ray Ozdemir, COO of framergy, Inc., is a mechanical engineer with a Master’s degree in industrial and systems engineering. He has over 15 years of experience in adsorbent development, scale up, and product development. Ray has been leading several new technology and product development projects funded by EPA and NSF as their principal investigator. He actively publishes in peer-reviewed journals and in conference proceedings.