Superfund Research Program
Understanding and Enhancing PFAS Phytoremediation Mechanisms Using Novel Nanomaterials
Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment and represent a health threat worldwide. More than 7,500 PFAS exist, and all have strong carbon-fluorine bonds that render them persistent in the environment. Therefore, effective alternatives for clean-up of PFAS are urgently needed. Phytoremediation is a promising technique for in-situ restoration of contaminated soil. However, plant uptake of PFAS is highly dependent on the length of the fluorinated chain portion of the molecule. As such, phytoremediation has limited effectiveness for larger PFAS, such as perfluorooctane sulfonic acid (PFOS).
In this project, the researchers propose to develop custom novel nanomaterials (NNMs) that facilitate internalization and mobility of PFAS into hemp plants. They hypothesize that carbon dots (CDs) and ultraporous mesostructured silica nanoparticles (UMNs) customized to have an increased affinity for PFAS will enhance PFAS uptake and translocation from water and soil into hemp plants. The luminescent properties of these novel materials will allow the team to visually track both PFAS sorption to the particles and nanoparticle movement into and throughout the plants, thus providing mechanistic information about their phytoremediation system.
The researchers will design, synthesize and test the affinity of customized CDs and UMNs for a mixture of two legacy, PFOS and perfluorooctanoic acid (PFOA), and two new, perfluorobutane sulfonic acid (PFBS) and GenX, PFAS. The nanoparticle-PFAS complex will be evaluated by 19F nuclear magnetic resonance and imaging techniques, while the sorption rate will be measured by liquid chromatography high resolution mass spectroscopy. They will also test if the NNMs promote phytoremediation in hydroponically grown plants. At the same time, they will use this simplified plant growth system to elucidate the mechanisms of NNM uptake by and translocation within plants. The group will analyze the uptake and localization of NNMs in plant tissues by imaging and spectroscopy techniques.
Additionally, the researchers will test the efficacy of NNM-enhanced phytoremediation in field soils obtained from PFAS-contaminated land. They will quantitatively analyze 25 PFAS and evaluate their uptake and translocation, and apply non-targeted analysis techniques to screen for thousands of PFAS that may be present in the soils and plants tested.
The nanomaterials developed in this project will advance phytoremediation as an economical and sustainable technique for removing a wide range of PFAS from soil. In addition, findings from this project will result in a better understanding of how NNMs mobilize contaminants in plant-soil systems, information that can be translated to optimize phytoremediation processes with other plant species, contaminant classes, and nanomaterials.