Per- and polyfluoroalkyl substances (PFAS) represent a class of synthetic chemicals that have garnered considerable attention due to their widespread occurrence in the environment and potential adverse effects on human health and ecosystems. These compounds, characterized by their strong carbon-fluorine bonds, have been extensively used in various industrial and consumer applications, including firefighting foams, non-stick cookware, and waterproof textiles. However, their persistence, bioaccumulative nature, and mobility in the environment have raised significant environmental concerns. PFAS have been detected in soil, water, air, wildlife, and even human bodies worldwide. Their adverse effects include developmental and reproductive toxicity, immune system disruption, and potential links to cancer. Given their pervasive presence and detrimental impacts, there is an urgent need to remove PFAS from the environment to safeguard human health and ecological integrity.

Within my group at the University of Adelaide, I lead fundamental research on PFAS fate, transport, and leaching from various environmental matrices, including soil, water, and biosolids. Below are a few examples of our ongoing research initiatives:

Systematic monitoring of PFAS remediation in soil

The in situ immobilization of PFAS in contaminated soils presents an immediate and cost-effective solution, effectively reducing PFAS leaching into ground and surface waters. This technology has been widely utilized both in Australia and globally to address PFAS and other toxic contaminants. Various sorbents, such as activated carbon, biochars, minerals, and mixed-composition commercial materials, are employed to bind and immobilize PFAS. While these materials have shown varying success in reducing PFAS solubility and transport in soils, a crucial question arises regarding their long-term binding capacity.

The degradation of sorbents, changes in soil properties (e.g., pH, salinity), environmental conditions (e.g., moisture content, temperature), or PFAS chemistry over time may compromise PFAS immobilization, leading to contaminant release. Previous research has indicated a reduction in PFAS leachability from soil two weeks after immobilization, but subsequent studies revealed a significant decrease in the efficiency of seven out of ten sorbents after four years, casting doubt on the long-term sorption ability of some sorbents. It is plausible that complex processes, including changes in sorbent properties or PFAS transformation, may influence the long-term stability of PFAS immobilization in soil. Alternatively, it could indicate a lack of effective testing tools.

To address these concerns, we plan to establish a first-of-its-kind in-field monitoring program and develop a systematic procedure to assess the durability of PFAS immobilization in soil. The research outcomes will facilitate accurate risk assessments and inform effective site management and remediation strategies, ultimately reducing the potential impact of PFAS on human and ecosystem health and wellbeing.

 Hydrodynamic cavitation as and efficient method to separate PFAS from water

This project aims to evolve foam fractionation technology to create a cost-effective, portable method to remove poly- and perfluoroalkyl substances (PFAS) effectively from water and other matrixes. High-shear mixing will be used to create micron-scale bubbles that boost PFAS adsorption from contaminated liquid. This approach uses off-the-shelf equipment either by itself to separate PFAS from different matrices or through incorporation into existing treatment processes. The combination of high-shear mixing and optimized mobilization solutions, developed with eco-friendly components, will address a current technology gap by being able to remove both short- and long-chain PFASs. Critically, this process occurs within seconds, a significant advantage over conventional foam fractionation.