PFAS sorbent tackles contaminated water

Researchers from Flinders University and the University of South Australia (UniSA) have developed an absorbent polymer that can safely and cost-effectively remove toxic polyfluorinated alkyl substances (PFAS) from contaminated water.

The polymer, made from waste cooking oil and sulfur combined with powdered activated carbon (PAC), adheres to carbon in a way that prevents caking during water filtration. PFAS uptake using the new technique is faster than the commonly used, and more expensive, granular activated carbon method. The new method also dramatically lowers the amount of dust generated during PAC handling, thus lowering respiratory risks faced by clean-up workers.

Nicholas Lundquist, PhD candidate at Flinders University and first author of the groundbreaking study published in Sustainable Chemistry & Engineering, said, “Our canola oil polysulfide was found to be highly effective as a support material for powdered activated carbon, enhancing its efficiency and prospects for implementation.”

PFAS, historically used in non-stick and protective coatings, lubricants and aviation firefighting foams, do not break down readily in the environment, resulting in contaminated groundwater and surface water.

“We need safe, low-cost and versatile methods for removing PFAS from water, and our polymer-carbon blend is a promising step in this direction,” said Flinders University’s Dr Justin Chalker, co-director of the study.

“The next stage for us is to test this sorbent on a commercial scale and demonstrate its ability to purify thousands of litres of water. We are also investigating methods to recycle the sorbent and destroy the PFAS.”

During the testing phase, the research team observed the self-assembly of perfluorooctanoic acid (PFOA) hemi-micelles on the surface of the polymer. Dr Chalker explained, “This is an important fundamental discovery about how PFOA interacts with surfaces.”

The team demonstrated the effectiveness of the polymer-carbon blend by purifying a sample of surface water obtained near a RAAF airbase. The new filter material reduced the PFAS content of the water from 150 ppt to less than 23 ppt, which is well below the 70 ppt guidance values for PFAS limits in drinking water issued by the Australian Government Department of Health.

Co-author and UniSA Research Fellow Dr Martin Sweetman commented, “This successful project has laid the groundwork for significant, ongoing, collaborative research between Flinders and UniSA, as well as with our two industry partners Membrane Systems Australia and Puratap.”

Funding for the start of this research came from the state government’s Defence Innovation Partnership program.

Image caption: Dr Justin Chalker (right) with Flinders University researcher Nicholas Lundquist testing metropolitan groundwater. Image credit: ©SA Government Defence Innovation Partnership.