Per- and polyfluoroalkyl substances (PFAS) are a set of emerging contaminants resulting from the use of aqueous film forming foams or similar products. PFAS are generally non-biodegradable and thus have long lifetimes in the environment. Measuring PFAS in surface and groundwater is important in understanding the transport and deciding upon remedial actions. A passive sampler for PFAS in aqueous systems will be developed and tested. A fast timetable is envisioned: the goal is to have a sampler fully developed and field tested within two years. Standard operating procedures (SOPs) will be developed in anticipation of future analysis by commercial and government laboratories. The passive sampler development leverages work conducted in SERDP project ER18-1300 where co-performers have developed organosilica adsorbents tailored to possess high capacity for PFASs regardless of chain length or charge state. As a result, work can begin immediately prototyping a passive sampler that is based on an organosilica absorbent placed in high density polyethylene (HDPE) housing. The project will progress through three phases: 1) passive sampler design selection, 2) performance validation in the laboratory and field, and 3) development of standardized methods that incorporate many of the protocols from US Environmental Protection Agency Method 537.1 and quality systems manual 5.2 to yield quality control and quality assurances using isotopic standards.
The project combines new adsorbent technology developed in an academic laboratory with Arcadis’ extensive field experience with PFAS in the environment. Passive samplers will use an organosilica adsorbent poly-quality assurance-Osorb that has both fluorophilic and ion-exchange functionality that allows high affinity for long-chain and short-chain PFAS. Fluoroalkyl groups are adsorbed to a hydrophobic expandable porous organosilica. The pores of the porous organosilica adsorbent contain a cationic polymer that binds anionic groups on perfluoro carboxylates and sulfonates, improving the affinity of short-chain compounds. Adsorbent will be placed in low cost 2.8×9.25 cm HDPE housings that can fit a wide range of monitoring wells, piezometers, and automated sampling systems, in addition to being able to be transported and analyzed in standard centrifuge tubes. An equilibrium-based sampler (preferred design) will be based on granular adsorbent placed between open mesh. An integrative design will be based on a single 1.0 cm diameter monolithic piece of adsorbent gel to allow a steady one-dimensional diffusion into the adsorbent disk. After a six-month benchmarking study, a final design will be selected. The selected design will then be evaluated and calibrated in a series of laboratory tests followed by field trials at up to three to five sites. Data obtained through these evaluations will be used to created SOPs for users and commercialized devices.
The development and demonstration of standardized procedures for field sampling of PFAS in environmental waters has been identified as a critical research priority. Releases of PFAS are known or suspected at more than 300 Department of Defense (DoD) sites, and as of December 2016, DoD has spent more than $200 million in sampling, analysis, and remediation. Passive samplers that can reach the market quickly offer a significant cost-savings to water analysis by simplifying sample collection, reducing shipping expenses, and reducing labor in the analysis, especially in the sample preparation steps. An additional benefit is the ability to leverage previous SERDP investments in developing Osorb media for PFAS adsorption.
Hartmann, Hefner, Carter, Liles, Divine, Edmiston, 2021. Passive Sampler Designed for PFAS Using Polymer-Modified Organosilica Adsorbent. AWWA Water Science, 3(4):e1237. doi.org/10.1002/aws2.1237.
Horst, Divine, Quinnan, Lang, Carter, Guillette, Pulikkal. 2021. Where is the PFAS? Innovations in PFAS Detection and Characterization. Groundwater Monitoring & Remediation, 42(1):13-23. doi.org/10.1111/gwmr.12502.
Edmiston et al., 2020. Passive Sampler, US Patent Application 16926144.