When Microplastics Meet PFAS: A Toxic Partnership in the Environment

Study reveals how different microplastics, especially polyamides, strongly adsorb PFAS, shaping pollution risks and remediation strategies.

PFAS and microplastics now appear together across rivers, oceans, sediments, and organisms, creating a complex, tightly linked pollution problem worldwide. Consequently, researchers increasingly ask how these two contaminant classes interact, and whether certain plastics act as especially efficient PFAS carriers.
Recently, a comprehensive study examined PFAS adsorption on diverse microplastic polymers, providing new insight into sorption mechanisms, driving forces, and environmental implications.

A Systematic Look at PFAS–Microplastic Interactions

First, the research team designed a broad screening framework rather than focusing on a single polymer or single PFAS compound. They evaluated eight PFAS molecules, spanning short- and long-chain structures, against 18 polymer types commonly found as secondary microplastics. Then, they used LC–MS/MS to quantify PFAS remaining in solution after contact with each microplastic, indirectly revealing adsorption capacity. Significantly, they optimized vials, filters, and handling steps to minimize unintended PFAS losses on laboratory materials, which could distort results.

Polyamides as PFAS “Super Sorbents”

In terms of performance, polyamide microplastics clearly stood out as the most powerful PFAS sorbents in the entire dataset. Specifically, PA 6, PA 6.6, and PA 10.10 sometimes removed nearly all PFAS from solution at 100 micrograms per liter. By contrast, common packaging polymers such as PE, PP, and PET generally exhibited much weaker PFAS uptake under similar experimental conditions. Moreover, TPU and ASA displayed intermediate to high adsorption, depending strongly on PFAS structure and solution chemistry. These results indicate that polymer functional groups, not just hydrophobicity, strongly control PFAS binding behavior at microplastic surfaces and interfaces.

How PFAS Structure and pH Steer Adsorption

Structurally, not all PFAS behave identically; molecular size and polarity significantly influence adsorption extent and sorption strength. For example, longer-chain, less polar PFAS typically adsorbed more strongly than shorter-chain, more polar analogues across many tested polymers. Additionally, solution pH played a decisive role, especially for polymers containing amide, carbonyl, or hydroxyl functional groups. At lower pH, these polymers showed substantially higher PFAS uptake, likely due to protonation and enhanced electrostatic or hydrogen-bonding interactions. However, at pH ten, adsorption dropped markedly for those same polymers, while simple polyolefins showed comparatively minor pH sensitivity. Thus, PFAS–microplastic interactions will vary across freshwater, wastewater, and estuarine systems, where pH fluctuates over space and time.

Beyond Surface Sorption: Time and Diffusion Effects

Regarding kinetics, most polymer–PFAS combinations appeared to reach adsorption equilibrium within approximately twenty-four hours of contact. Yet, extended experiments revealed that PET continued absorbing PFAS over several weeks, suggesting diffusion into the polymer bulk phase. Therefore, long-residence microplastics may accumulate PFAS far beyond what short-term equilibrium tests would otherwise predict.

Modeling Confirms Strong Polyamide–PFAS Binding

To complement experiments, the authors employed computational modeling using a neural-network potential followed by semi-empirical re-optimization. The calculated interaction energies confirmed much stronger binding for polyamide–PFAS pairs than for PE–PFAS combinations. Whereas PE–PFAS interactions fell around minus thirty to minus forty kilojoules per mole, polyamide–PFAS values exceeded minus one hundred kilojoules. Consequently, modeling supported the conclusion that polyamides act as robust PFAS sorbents, while simple hydrocarbon backbones bind relatively weakly.

Environmental Risks and Remediation Opportunities

From an environmental perspective, these findings present both risks and potential opportunities.
On one hand, polyamide microplastics may behave as particularly potent PFAS vectors, concentrating contaminants and transporting them through food webs.
They could enhance PFAS exposure for organisms ingesting or contacting polyamide particles, especially under lower-pH conditions. On the other hand, similar chemistries might be intentionally engineered into sorbent materials for PFAS removal in treatment systems. However, any remediation strategy must carefully manage sorbent regeneration, disposal, and microplastic release to avoid creating secondary pollution pathways. The authors call for field-scale studies incorporating realistic temperature, salinity, pH, organic matter, and biological activity. Such work will be essential to translate laboratory PFAS–microplastic insights into accurate environmental models and effective mitigation strategies.