Titanium Metal Organic Frameworks break down PFAS using UV light
The crisis of PFAS contamination (sometimes publicly referred to as PFOA, PFOS or GenX contamination) of drinking water and its threat to public health will be the focus of a major Hollywood film coming this November. Exposure to PFAS can be harmful to humans, potentially resulting in kidney cancer, liver damage, and developmental problems in children. The substance can build up in humans and animals over years, elevating the risk.
PFAS, or Per- and polyfluoroalkyl substances, what the US Food & Drug Administration has coined ‘Forever Chemicals’ due to their persistence in the human body, were very popular with consumer product chemists due to their hydrophobic chains which allow for the material to push water away and create a non-stick coating. The substance can be found in food packaging, cooking apparatuses and furniture. It is also common in firefighting foams, which has led to significant contamination of water sources where these foams are deployed.
Though there are ways to collect PFAS, there has been little in planning for what to do with the contaminant. Chemical engineers are developing some methods to completely destroy collected PFAS, but they require offsite processes which are either highly energy intensive or require burying the conjoined absorbent/PFAS material as a new form of permanent waste. For the former, temperatures of 1000 °C (~1800 °F) are required, and few adsorbents used to collect the chemical can survive such heat. With either process, the cost to the environment is still high.
Enter MOFs: Metal Organic Frameworks, or MOFs for short, are crystalline 3D structures with incredible internal surface area which translates into an unbelievable ability to absorb molecules. A technique to cause defects in MOFs designed at Rice University has already shown that the materials can absorb over two times the industrial standard, activated carbon. In May 2019, framergy, Inc., the first MOF company, was funded to explore PFAS destruction by the US Environmental Protection Agency (EPA), under their Small Business Innovation Research (SBIR) program. The research, in partnership with Texas A&M University, explores how MOFs capture PFAS, and then subjects the MOF and guest PFAS molecules to ultra violet light.
framergy scientists are using ARYSORB™ T125, a titanium MOF that is structurally similar to the UiO-66 variety used by the Rice scientists. ARYSORB™ T125 is based on MIL-125-NH2, which was first discovered in 2008 by Gerard Ferey and Christian Serre of the Centre national de la recherche scientifique (CNRS). In ARYSORB™ T125, titanium oxo clusters are periodically arranged and separated by organic linkers, which leads to a highly accessible and large surface area. The titanium nodes can then act upon the guest PFAS molecule as a photocatalyst, something not possible in UiO-66. This material is exclusively licensed to framergy, along with all other known titanium-based MOFs, by CNRS, and is available at commercial scale through Strem.com and the Company.
Destruction tests were performed using PFAS in an aqueous solution with ultra violet light (UV), and the results showed that ARYSORB™ T125 was capable of degrading the contaminant through Fluorine-19 nuclear magnetic resonance. Further testing of two species, PFOA and PFOS in the presence of the MOF, clearly proved that water borne PFAS species could be captured and broken down into smaller, less harmful substances, with the use of readily available UV light. This was confirmed through liquid chromatography mass spectrometry, and is the first known demonstration of PFAS photocatalysis.
framergy is aggressively scaling the technology for commercialization through the EPA SBIR program at a time when PFAS are being addressed by the agency through "the most comprehensive cross-agency action plan for a chemical of concern ever undertaken by the agency", according to Director Andrew Wheeler. The next step will be to complete Phase I of the program and apply for a Phase II award. “EPA’s SBIR Program is pleased to support small businesses such as framergy that are working to bring their innovative ideas to the market to solve tough environmental issues such as treating PFAS in water.” stated April Richards, SBIR Program Manager at the EPA.
This breakthrough removes key obstacles in the war on PFAS. According to company Chief Operating Officer, Ray Ozdemir, “our Company’s titanium metal organic frameworks have proven to not only capture dangerous PFAS in water systems, but to break them down to be less bio-accumulative with the help of the sun.” The Company is also using the materials for novel personal care usage such as sun blocks and pollutant scavengers on the skin.