Grantee Research Project Results
Final Report: Applying Passive Samplers to Assess Perfluoroalkylated Substances in Soils and Sediments
EPA Contract Number: 68HE0D18C0017Title: Applying Passive Samplers to Assess Perfluoroalkylated Substances in Soils and Sediments
Investigators: Chance, Daniel
Small Business: Accurate Environmental Laboratories
EPA Contact: Richards, April
Phase: I
Project Period: October 1, 2018 through March 31, 2019
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2018) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Land Revitalization
Description:
Per- and polyfluoroalkyl substances (PFAS) are a class of organic compounds possessing carbon-fluorine bonds that make them recalcitrant in the environment. PFAS have a hydrophilic head and a hydrophobic and lipophobic tail that makes them useful as repellents and coatings. PFAS have been used extensively in non-stick cookware, firefighting foams, stain resistance products paints, pesticides, food packaging, and personal care products. Recent research has demonstrated that PFAS bioaccumulate and cause liver and immune system dysfunction. There is a critical need to develop approaches for assessing the fate and transport of PFAS in areas of historic releases to protect human health and the environment.
Sediments and soils often act as a sink for the contaminants such as PFAS following their release that presents risks years after the control of sources. Passive samplers provide a mechanism to infer the bioaccumulation risks associated with residual contamination in soils and sediments indirectly by mimicking biological uptake. The long-term goal of this research was to develop a standardized passive sampling method for PFAS in contaminated soils and sediments. The objective of this phase in the development was to demonstrate the feasibility and assess the commercial potential for a prototype passive sampling device for PFAS.
The proposed passive sampler makes use of a sorbent resin within a stainless steel housing that accumulates PFAS from the surrounding environment via diffusion processes. The sampler is designed to be placed into a soil or sediment bed, allowed to accumulate PFAS, then removed and analyzed. The housing for the sampling device consists of three washers that are used to secure two permeable membranes with four wingnuts and bolts for structural integrity. The two disk microfiltration membranes are secured with the housing and enable passage of the PFAS into the sampler where the compounds accumulate on the resin. The device is assembled and then deployed into an environmental medium containing PFAS where it accumulates the compounds for a predetermined period, after which it is analyzed. Analysis consists of disassembly of the housing, recovery of the sorbent resin material, and elution of the PFAS from the resin with a solvent extraction. The eluent is then re-constituted and analyzed for PFAS using liquid chromatography with tandem mass spectrometry (LC/MS/MS).
For this project, over 130 samplers were manufactured and then tested for efficacy in a series of experiments designed to determine the PFAS accumulation process in saturated, contaminated soils. Due to time limitations, the analysis was focused on three PFAS, perfluorooctainoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorobutane sulfonate (PFBS). For each experiment, PFAS was spiked into a soil-water matrix and allowed to equilibrate. Ten samplers were placed into the soil-water matrix in each experiment, then removed periodically and tested for PFAS over a 28-day period. An additional experiment was performed using PFAS spiked into only water as a control for the effects of the soil matrix. Results were interpreted using a simple mass transport model that has previously been developed in the literature.
Summary/Accomplishments (Outputs/Outcomes):
The prototype passive sampler was successfully assembled using the proposed design. The device can be manufactured reproducibly and relatively inexpensively. Preliminary tests with the proposed resin and the long-term kinetics uptake experiments showed good accumulation for the three PFAS, which provides good evidence of the potential for this technology to passively sample PFAS. The samplers did not appear to have reached equilibrium in control (water-only reactor) in the 28-day experimental period, which was inconsistent with expectations. The result may have occurred because of the quiescent experimental conditions that are unlikely in natural aquatic systems. The passive samplers appeared to have reached near equilibrium levels in the soil-water experiments in the 28-day period.
Sorption uptake experiments for the samplers were performed for two different soils, which all showed similar behavior. One of the soils was combusted in a furnace to remove labile carbon, although the uptake in the sampler was similar to the non-combusted soil. The soil-water matrix appeared to increase the overall kinetic rate versus the water-only reactor, likely due to the increased local concentration levels in the vicinity of the sampler. Sampler uptake kinetic experiments were performed in the soil-water matrices with each compound individually and as a mixture to assess the potential for competitive sorption effects. The results of all experiments showed lower levels of each PFAS in the mixed versus individual reactors. These results indicate that the PFAS compete for sorption sites, and thus the approach will require a more complex analysis of the competitive sorption processes before it can be accurately used for field passive sampling where many compounds are present.
Conclusions:
The feasibility of the passive sampling device to accumulate PFAS in soil-water matrices has been demonstrated. Sorbent-water coefficients for PFOA, PFOS, and PFBS were 1205 L/kg, 1222 L/kg, and 1171 L/kg, respectively. Competition exists between the various PFAS for the sorption sites on the resin. The experiments demonstrated that a new and more complex model is needed to interpret accumulated PFAS on the sampling materials. Further work is needed to assess a larger suite of PFAS, including performance reference compounds that can be used to infer kinetics. A competitive sorption model will be needed to interpret accumulation in field sites.
Commercialization:
The value proposition for this technology is a less labor intensive and better risk characterization method of sampling and monitoring levels of PFAS compounds at investigatory or remediation sites. The market for PFAS detection and remediation is fragmented, emerging, and large. Overall, there would seem to be significant opportunity for new solutions with the right value proposition at decent price points, and interest is high for such solutions in many sectors. From a technical perspective, a PFAS passive sampler must be accurate, reliable, and applicable for a broad spectrum of PFAS at very high sensitivity in heterogeneous samples. Interviews were conducted with leading universities researching PFAS, environmental consulting firms, environmental labs, and the US Air Force. Several top global environmental engineering consulting firms were interested and eager to hear about new solutions. One apparent commercialization strategy may be to partner with one or more of these firms for development, validation, and distribution of the subject technology. While these firms do not directly pay for testing, they do provide recommendations on the best science to responsible parties and government entities that may be concerned with PFAS presence in their facilities. Environmental consulting firms thus may represent an indirect channel for commercialization.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 1 publications | 1 publications in selected types | All 1 journal articles |
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Atoufi H, Lampert D. Analysis of a Passive Sampling Device to Assess the Behavior of Per- and Polyfluoroalkyl Substances in Sediments. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2023; |
68HE0D18C0017 (Final) SU840180 (Final) |
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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.