Native Plant PFAS Remediation: Harakeke Tackles Forever Chemicals at University of Auckland

University of Auckland's Breakthrough in PFAS Removal Using Native Harakeke

Researchers at the University of Auckland have made a significant discovery by harnessing the power of harakeke, New Zealand's iconic native flax plant, to combat per- and polyfluoroalkyl substances (PFAS), commonly known as 'forever chemicals.' This innovation, detailed in a recent study published in ACS ES&T Engineering, showcases how a culturally significant taonga species can be chemically modified to effectively strip these persistent pollutants from water. The interdisciplinary effort involving the School of Chemical Sciences, School of the Environment, and Faculty of Engineering highlights the university's commitment to addressing environmental challenges through cutting-edge science.

In laboratory tests, treated harakeke fibers demonstrated remarkable efficiency, removing up to 99% of some of the most stubborn short-chain PFAS variants. This development is particularly timely for New Zealand, where PFAS contamination has been detected in groundwater near military bases and even in drinking water supplies, prompting regulatory actions like the upcoming ban on PFAS in cosmetics by the end of 2026.

What Are PFAS and Why Are They a Problem in New Zealand?

Per- and polyfluoroalkyl substances (PFAS) are a group of over 4,700 synthetic chemicals developed in the 1940s for their water- and grease-resistant properties. Used in products like non-stick cookware, waterproof clothing, firefighting foams, and cosmetics, PFAS do not break down easily in the environment or human body, earning them the moniker 'forever chemicals.' They bioaccumulate, linking to health issues such as cancer, reduced fertility, and immune system disruption.

In Aotearoa New Zealand, PFAS hotspots include Royal New Zealand Air Force bases like Ohakea, where groundwater plumes have been identified. A 2022 shutdown of an Auckland water treatment plant due to high PFAS levels underscores the urgency. Nationwide sampling by University of Auckland researchers confirmed low but detectable levels in drinking water, emphasizing the need for effective remediation strategies.

Harakeke: A Taonga with Deep Cultural Roots

Harakeke (Phormium tenax), or New Zealand flax, is more than a plant; it's a taonga species central to Māori culture. Pre-colonization, Māori used its strong fibers for weaving kete (baskets), ropes, clothing, and fishing nets, while its sap served medicinal purposes and nectar as a sweetener. Settlements were often built near harakeke-lined streams, as the plant naturally absorbs pollutants through its roots, purifying water—a trait now leveraged scientifically.

Botanically a lily family member, harakeke grows prolifically across Aotearoa, making it a sustainable, low-cost resource. Sourced from mills like Templeton Flax Mill in Riverton, its rigid, nonporous fibers are ideal for water treatment applications.

The Research Team Driving Innovation at UoA

Leading the charge is PhD student Shailja Data, who conducted the lab experiments, alongside Dr. Lokesh Padhye (honorary academic and Associate Director at New York State Center for Clean Water Technology), Professor Melanie Kah (School of the Environment), Professor David Barker (School of Chemical Sciences), and Associate Professor Erin Leitao (also School of Chemical Sciences and MacDiarmid Institute). This collaboration spans environmental science, chemistry, engineering, and materials nanotechnology.

The project builds on Barker's 2019 work under a government-funded initiative, evolving from nitrate removal to PFAS focus. "Capturing forever chemicals would only add to the story of harakeke’s remarkable versatility," notes Professor Kah. Such teamwork exemplifies higher education's role in tackling real-world problems.

For aspiring researchers, UoA offers opportunities in environmental engineering and chemistry. Explore research assistant jobs or NZ academic positions to join similar projects.

How Chemically Treated Harakeke Works: Step-by-Step

The process transforms raw harakeke fibers into a high-performance sorbent through atom transfer radical polymerization (ATRP):

• Step 1: Wash fibers with acetone and methanol, then ultrasonicate in water.
• Step 2: Esterify with 2-bromopropionyl bromide to create a macroinitiator.
• Step 3: Graft 20% by weight poly-[2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC) using copper catalyst at 40°C, yielding quaternary-ammonium groups for electrostatic attraction to anionic PFAS.
• Application: Add 50 mg/L treated fibers to contaminated water, shake for 24 hours; PFAS bind via electrostatic and hydrophobic interactions.

This yields rigid fibers suitable for packed-bed filters.

Impressive Lab Results and Key Statistics

In batch tests with 100 μg/L multi-solute PFAS, 50 mg/L treated harakeke removed 86% PFBS (perfluorobutanesulfonic acid) and 57% PFBA (perfluorobutanoic acid), outperforming granular activated carbon (GAC) and matching ion-exchange resins. Equilibrium reached in 4-24 hours, with up to 99% removal for short-chain PFAS like PFPrA.

Langmuir isotherms showed max capacities up to 43 mg/g for PFBS. Stable across pH 5-7, resilient to natural organic matter (8% reduction with tannic acid), and effective in Auckland tap water up to 100% for PFBS at moderate concentrations.Read the full study.

Advantages Over Traditional PFAS Treatments

• Sustainable Sourcing: Renewable, native plant vs. synthetic GAC/polystyrene.
• Cost-Effective: Low feedstock cost, regenerable.
• Regenerable: >78% PFBS, 97% PFBA recovered with MeOH/1% NaCl, enabling cyclic use.
• Versatile: Handles short-chain PFAS (hardest), multi-solute, real water matrices.
• Culturally Aligned: Revives Māori knowledge in modern science.

"The sustainability and availability make it particularly promising," says Dr. Padhye.

Regeneration, Scalability, and Real-World Potential

Desorption uses brine-assisted methanol wash, preserving sorbent integrity for reuse. Nonporous rigidity suits column filters. Scaling could treat NZ sites like Ohakea or urban streams. Challenges include optimizing for ultra-low concentrations and field trials, but UoA's MacDiarmid ties accelerate translation.

Professor Barker envisions harakeke filters replacing eco-unfriendly materials across scales.UoA News.

Implications for New Zealand's Environment and Public Health

This UoA-led advance supports NZ's PFAS strategy, protecting whenua and tangata. With drinking water safe but vigilant monitoring needed, harakeke offers a homegrown solution. Broader impacts: boosts biodiversity via native planting, aligns with Te Tiriti principles.

Students in environmental science at NZ universities like UoA are at the forefront. Check research career advice, adaptable to NZ.

Future Outlook: From Lab to Widespread Adoption

Ongoing work includes field pilots and PFAS alternatives research by Leitao. Potential partnerships with iwi for commercial harakeke cultivation. Globally, it positions NZ higher ed as a leader in green remediation.

Photo by Het Suthar on Unsplash

Career Opportunities in PFAS Research at NZ Universities

UoA's success opens doors for postdocs, lecturers in chemistry and env eng. Explore faculty positions, postdoc roles, or university jobs in NZ. Rate professors via Rate My Professor for insights. For advice, visit higher ed career advice.

This research not only cleans water but inspires the next generation of Kiwi scientists.