WCP Online: A Plant Based Adsorbent That PFAS Can’t Resist

Apr 2, 2024 | News

“Nothing lasts forever” seemed to be a safe truism—until per- and polyfluoroalkyl substances (PFAS) came along. Referred to as forever chemicals, PFAS are an increasing threat to human health and the environment. These chemicals are pervasive in the environment, having been used for decades in industrial manufacturing and consumer products, and as a fire suppressant. PFAS abound in hundreds of everyday consumer goods, including personal care products, food packaging, waterproof clothing, stain-resistant fabrics, and electronic devices. Environmental exposure comes from direct product usage and contamination of drinking-water supplies.

PFAS are made up of and derive their properties from carbon-fluorine bonds, which are one of the strongest bonds in organic chemistry. These bonds are the reason for PFAS persistence in the environment. PFAS chemicals enter drinking-water supplies through various pathways, including discharges from industrial facilities, wastewater treatment plants, and landfill operations (leachate). Water bodies adjacent to airports and military installations are vulnerable to contamination from use of PFAS-containing firefighting foams.

PFAS have the same persistence in people and other living organisms as they do in the environment. Studies have shown long-chain PFAS, such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), accumulate and remain in the body for years after exposure. These chemicals are highly toxic at low concentration and can lead to severe health concerns, particularly for vulnerable populations such as infants and pregnant individuals. Adverse effects to exposure include a compromised immune system, an increased risk of developing certain cancers, elevated cholesterol levels, and other health issues.

New regulation of PFAS in drinking water has increased the urgency for effective treatment technologies. Relying on comprehensive toxicology data, the U.S. Environmental Protection Agency (EPA) proposed nonenforceable maximum contaminant level goals (MCLGs) for PFOA, PFOS, and four other PFAS in March 2023. Finding that PFOA and PFOS are likely to be carcinogenic to humans, the agency set MCLGs of zero for each chemical. To establish a national drinking-water standard, the EPA proposed maximum contaminant levels (MCLs) as close as feasible to the PFAS MCLGs, leading to MCLs of four parts per trillion (ppt) each for PFOA and PFOS.

“With new EPA regulations of PFAS in drinking water due soon, we are excited to provide customers with a selection of advanced filtration products to protect their water at home from PFAS,” said Frank Cassou, Cyclopure chief executive officer. “EPA has said there is no safe level of PFOA or PFOS in drinking water. We agree. Our filters are designed for full removal of those chemicals to non-detect. Customers should feel secure about the water their family drinks.”

Cyclopure is a materials science and environmental engineering firm headquartered in Chicago, Illinois. The company has developed a cyclodextrin adsorbent (DEXSORB®) that fully eliminates PFAS from water. DEXSORB is being commercialized for multiple PFAS related uses, including (i) environmental monitoring, (ii) residential filtration, and (iii) municipal and industrial treatment systems.

A Novel Adsorbent Designed to Remove PFAS
As regulatory limits for PFAS exposure tighten to zero tolerance, nonselective adsorption technologies face increasing challenges to meet the more stringent requirements. Traditional treatment applications will require larger media volumes to achieve MCLs, compounding PFAS waste disposal under proposed rules to regulate the generation, transportation, and disposal of PFAS-containing waste materials.

DEXSORB is a plant-based adsorbent made with beta-cyclodextrins. It was developed to remove PFAS and other organic micropollutants from water supplies. The media utilizes molecular selectivity to target PFAS with rapid, high-capacity adsorption.

Exploiting hydrophobic cavities, cyclodextrins have been used for decades in personal care products, pharmaceuticals, and the food industry. In native form, however, cyclodextrins are not available for use in water treatment due to their inherent water-soluble nature.

Cyclopure was formed to develop technologies that permit the use of cyclodextrins in water to remove organic micropollutants. Following several years of development, Cyclopure optimized multiple chemistries for commercial preparation of high-capacity cyclodextrin polymer adsorbents. Tailored to remove PFAS from water, DEXSORB is the first commercial product to come out of the company’s cyclodextrin technology science.

Engineered treatment systems that use DEXSORB operate in a continuous-flow packed bed filtration (PBF) process, treating drinking water, groundwater, wastewater, landfill leachate, and reverse osmosis (RO) permeate or concentrate. The continuous-flow PBF process operates using lead-lag vessel configurations without requiring preconcentration or effluent polishing. The media has demonstrated removal performance, high capacity, and efficient media use in operations across the U.S. After successful completion of a yearlong drinking-water pilot in Newburyport, Massachusetts, the Massachusetts Department of Environmental Protection recently granted new technology approval for the use of DEXSORB in drinking-water treatment in the state.

DEXSORB is made in powder and granular forms, and offers advanced features to provide effective removal of PFAS to nondetect levels:

  • Molecular selectivity: DEXSORB is made up of uniform 0.78-nanometer cyclodextrin hydrophobic cavities that uptake diverse PFAS structures by size inclusion, selectively targeting contaminants within the 150-1,000 dalton range. By reciprocal function of size exclusion, media performance is not impacted by matrix effects of natural organic matter (too large, over 1,000 dalton) and inorganic ions (too small, less than 150 dalton).
  • High capacity and treatment efficiency: With 300 quintillion uniform cyclodextrin cavities in each gram, DEXSORB features rapid adsorption kinetics and high treatment capacity, free from competing effects. This enables lower media volume requirements and effective treatment across various drinking-water applications, including groundwater, surface water, and RO permeate/concentrate.
  • Resistance to fouling: DEXSORB is not subject to biodegradation and does not experience biofouling, ensuring smooth system operation and sustained performance.
  • Desorption and media reuse: DEXSORB offers a sustainable solution, as the media can be regenerated for several cycles of reuse. Regeneration is accomplished in a solution-based desorption process that is performed under ambient conditions to separate PFAS waste and fully restores DEXSORB media capacity.
  • Sustainable waste disposal: A beneficial output of regeneration is that extracted PFAS are isolated and further processed into a concentrated waste stream for efficient handling and disposal by existing destruction technologies. This avoids disposal complications encountered by single-use media and prevents captured
  • PFAS from recontaminating the environment.
  • Certified for drinking-water treatment: DEXSORB is certified under NSF/ANSI/CAN 61, ensuring its safe use in potable water systems for public consumption.

Municipal PFAS Media Available to Households in Point-of-Entry Solution
With its various certifications and accreditations, DEXSORB’s unique adsorption properties are available for use in a wide range of applications to address PFAS contamination of drinking-water supplies. Applications span large-scale engineered treatment systems, environmental monitoring, and residential use.

Due to its high PFAS adsorption efficiency, DEXSORB is being utilized as a sorbent to extract PFAS in water samples for environmental monitoring. The National Institute of Environmental Health Sciences assisted in the development of a PFAS water test kit that permits convenient and affordable grab-sample testing without the need to ship water back to a lab for analysis. The media is also used as a PFAS extraction sorbent in a groundwater monitoring product called FluxTracer from Regenesis.

Residential Use
The same highly effective DEXSORB media employed by engineered treatment systems is also available for home use in two high-capacity, whole-home systems. To encourage the return of spent filters after use, an exchange program is in place for filter replacements. The program is designed to safely dispose of extracted PFAS and to regenerate DEXSORB media.

Residential DEXSORB Filtration Case Study
Faced with PFAS levels up to 40 ppt in their well water in Shamong, New Jersey, members of a family participated in a product pilot program in combination with preexisting softener and pH neutralizer filtration systems. Their filter has operated efficiently since May 2023, with no pressure buildup and nondetect PFAS removal.

Zero PFAS Is Real
DEXSORB is a versatile and highly efficient adsorbent being deployed throughout the water cycle to protect drinking water from PFAS contamination. With rapid kinetics and high capacity, the media is ready to meet the challenges of new regulatory limits and to prevent recontamination by efficient handling of PFAS waste streams.

About the author Maribeth Broms is a consumer products associate at Cyclopure. She holds a bachelor’s degree in marine biology and a master’s degree in marine environmental science, both from Nova Southeastern University. She can be reached at mbroms@cyclopure.com. Cyclopure is a materials science and environmental engineering firm headquartered in Chicago, Illinois. Visit https://cyclopure.com/ for more information.

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