AFFF-impacted concrete pavements represent a large and persistent reservoir of per- and polyfluoroalkyl substances (PFAS) with limited disposal options. This study demonstrates that the naturally high calcium-to-fluorine molar ratio (>50:1) in Portland cement concrete (PCC) enables near-complete PFAS mineralization at 500 °C, well below the > 1000 °C required for conventional incineration. Mineralization onset varied by PFAS structure (350-450 °C), and at 500 °C, PCC converted 95 to > 99% of PFAS-derived fluorine to stable inorganic products within 1 min. This rapid conversion reflects the higher thermal conductivity of PCC relative to granular activated carbon (GAC) and the reactivity of calcium phases with fluorinated intermediates formed after headgroup cleavage. Destruction and removal efficiency (DRE) exceeded 99.99% across all matrices tested, including GAC, sand, and gravel, yet only the cement-based materials achieved high mineralization. GAC mineralization remained below 40% even after 15 min, demonstrating that DRE alone is an insufficient metric for evaluating PFAS thermal treatment. FTIR off-gas analysis confirmed that fluorinated products of incomplete destruction (PIDs) accounted for less than 2% of the initial fluorine mass during PCC treatment. Demonstration using two field-collected AFFF-impacted concrete cores spanning nearly three orders of magnitude in PFAS concentration (0.1 and 48 μg/g total PFAS) confirmed average DREs exceeding 99.9%, with greater than 95% of fluorine recovered as mineralized products in the solid. These results establish low-temperature thermal treatment as a viable, scalable approach for PFAS-contaminated concrete and highlight the need for total fluorine measurements alongside targeted PFAS analysis to verify true mineralization.

Fluorotelomer carboxylic acids (FTCAs) are key intermediates in the environmental transformation of fluorotelomer-based precursors, yet their abiotic degradation pathways remain poorly understood. This study investigates the hydroxide-promoted transformation of n : 2 FTCAs at ambient temperature and under controlled laboratory conditions to elucidate reaction mechanisms and kinetics. Equilibrium experiments were performed across sodium hydroxide (NaOH) concentrations ranging from 1 × 10-5 to 1 M, revealing transformation onset between 1 × 10-4 and 2 × 10-4 M. Both 6 : 2 and 8 : 2 FTCA were fully converted to the corresponding unsaturated products (FTUCAs) at ≥5 × 10-4 M NaOH, followed by secondary loss of FTUCA at higher base concentrations (>2 × 10-3 M) to undetected nontarget products. Minor yields (<7%) of perfluorocarboxylic acids (PFCAs) were detected at ≥0.1 M NaOH. Kinetic experiments at 1 × 10-2 M NaOH showed first-order transformation of 6 : 2 and 8 : 2 FTCA, with observed rate constants (kobs) of 0.09 and 0.48 h-1, respectively. When repeated with 0.3% ammonia (NH3; [OH-] ∼ 1.74 × 10-3 M) and 6 : 2 FTCA, the kobs decreased sixfold (0.015 h-1) relative to NaOH, consistent with the approximately sixfold lower [OH-]. Because 0.3% NH3 is commonly used in PFAS extraction methods, these results suggest that prolonged extractions may lead to underestimation of FTCAs and potentially other precursors. Experiments with a base-containing consumer cleaning product confirmed that this hydroxide-promoted transformation of 6 : 2 FTCA to 6 : 2 FTUCA also occurs in more complex matrices. Mechanistic analysis supports a reversible E1cb pathway in which deprotonation of the α-hydrogen generates a stabilized carbanion intermediate, followed by unimolecular C-F bond cleavage. This study provides the first evidence of abiotic FTCA transformation via an E1cb mechanism and highlights the potential for mild alkaline environments, including those in analytical and household contexts, to promote PFAS precursor transformation.

The application of heterogeneous catalysts for destruction of per- and polyfluoroalkyl substances (PFAS) in subcritical hydrothermal water (350 degrees C, 16.5 MPa) is a promising remediation strategy. Among catalysts screened, carbon-supported noble metals (Ru/C, Rh/C, Pt/C, and Pd/C) were more effective than metal oxides (Al2O3, FeOOH, TiO2, and ZrO2) at promoting degradation and defluorination of perfluorobutane sulfonic acid (PFBS), a representative perfluoroalkyl sulfonic acid (PFSA). After 3 h, PFBS and perfluorooctane sulfonic acid (PFOS) were degraded > 98% and defluorinated > 10% by a 5 wt% ruthenium-on-carbon (Ru/C) catalyst. Defluorination increased to > 20% when reaction was extended to 5 h, but a large fraction of the fluorine mass balance remained unaccounted for. Mono-substituted PFSA intermediates were identified in solution and unextractable organic fluorine species on the Ru/C surface were confirmed by spectroscopic analysis. The bound species were released to solution as F- when exposing the Ru/C to hydrothermal alkaline treatment (HALT) conditions (1 M NaOH, 350 degrees C), closing the fluorine mass balance. A tentative mechanism initiated by homolytic cleavage of carbon-carbon and carbon-sulfur bonds along the perfluoroalkyl chain is proposed, with chemisorbed fluorine resulting from coupling of C-centered radicals to the carbon support. These findings introduce an innovative strategy for more sustainable remediation of PFAS contamination.

The structural diversity and complex transport behavior of per- and polyfluoroalkyl substances (PFAS) complicate a universal characterization of their removal in membrane systems. This study compiles 2353 data points from the literature on PFAS rejection by nanofiltration and reverse osmosis membranes, spanning a broad range of PFAS, membranes, feedwater compositions, and operating conditions. Using machine learning, this data set is modeled to evaluate how solute, membrane, and solution properties jointly influence PFAS removal. Of the 13 experimental system descriptors analyzed, membrane water permeance and PFAS molecular volume demonstrated the strongest main effect on rejection, emphasizing the significance of steric exclusion. The effects of background ions and dissolved organic matter were highly condition-dependent, exhibiting nonmonotonic behavior governed by competing mechanisms. Low concentrations of organic matter and ions enhanced PFAS rejection, consistent with complexation that increases apparent solute size, while higher concentrations reduced PFAS rejection, indicating that charge shielding and concentration polarization increasingly drive transport behavior. Overall, this analysis provides a unified, data-driven framework for interpreting previously inconsistent findings across studies, identifies critical gaps in existing experimental data, and highlights opportunities to guide targeted membrane design and treatment strategies.

The widespread persistence and global distribution of per- and polyfluoroalkyl substances (PFAS) have intensified interest in thermal treatment technologies for permanent destruction, particularly during incineration of contaminated soils and spent PFAS adsorbents. However, evaluating destruction efficiency remains challenging due to difficulties in closing fluorine mass balance. Hydrogen fluoride (HF) is commonly used as an indicator of fluorine mineralization, yet its quantitative recovery can be strongly influenced by matrix-dependent processes. Here, we investigate analytical barriers to fluorine mass balance during simulated incineration using combustion ion chromatography across 21 PFAS-laden materials, including ion exchange resins, granular activated carbons, soils, and soil components. Samples spiked with perfluorooctanesulfonic acid or sodium fluoride were combusted at 800, 900, and 1050 °C, and fluorine recovery was quantified via HF. Fluorine recovery showed strong matrix dependence. Soils and some clays exhibited elevated recoveries (>100%) due to background fluorine release, whereas calcium- and clay-rich materials showed suppressed or highly variable recoveries due to fluorine retention in mineral-associated forms. Ion-exchange resins exhibited recoveries near 100% but with variability linked to analytical interferences, including a non-monotonic response to moisture, where intermediate moisture levels decreased apparent recovery while higher moisture improved it. These findings demonstrate that fluorine recovery is governed by matrix composition, fluorine speciation, moisture effects, and analytical limitations, rather than PFAS mineralization alone, and should be interpreted with caution when assessing thermal treatment performance.

Semiconductor manufacturing is rapidly expanding alongside tightening environmental regulations and increasing public concern around per- and polyfluoroalkyl substances (PFAS). Because of their unique chemical properties, PFAS are used across numerous processes in semiconductor manufacturing. Given process complexity and lengthy development timelines for alternatives, eliminating PFAS use in this industry is not currently feasible. Developing practical technologies for PFAS waste management is therefore critical but uniquely challenging in semiconductor manufacturing due to the nature of waste streams (parts-per-billion PFAS concentrations, complex backgrounds including hundreds of chemicals, prevalence of ultrashort PFAS, total stream volumes up to 35,000 m3 per day per facility, and distribution across gas, liquid, and solid phases) and significant constraints on space and systems redesign. This review describes recent developments and key questions that must be addressed to develop impactful and commercially viable detection and abatement methods for PFAS waste management in semiconductor manufacturing. Integrating these technologies into compact, high-performance systems and testing them under realistic conditions (complex PFAS mixtures, high fluoride/ionic strength, pH 6-11, low contact time, process variability) through industrial collaborations is essential for scalable, cost-effective solutions. Research addressing semiconductor industry-specific PFAS waste is essential to enable environmental compliance while supporting the continued growth of semiconductor manufacturing.

Per- and polyfluoroalkyl substances (PFASs) are synthetic chemicals used across numerous industrial and consumer applications. Their persistence and toxicological impacts necessitate their removal from the environment and their complete destruction; however, many PFAS destruction technologies release gas-phase and aerosol-phase fluorinated products of incomplete destruction (PIDs). In this Review, we discuss the PIDs released by PFAS destruction methods and approaches to categorize and measure them. Existing and emerging technologies use thermal, chemical, electrical or biological approaches to degrade PFASs, with varying degrees of success. Although many technologies achieve destruction and removal efficiencies of more than 99.99

The chemical properties of perfluoroalkyl and polyfluoroalkyl substances (PFAS) pose a significant remediation challenge. This study investigated smoldering combustion to destroy PFAS while scaling up from the lab to field implementation. The first phase consisted of bench-scale tests using a model soil system. Calcium oxide (CaO) was used as a soil amendment in some of the test cases. For all test conditions, greater than 99.9% removal of PFAS was achieved. Post-treatment soils without CaO amendments were found to have a significant reduction in total fluorine concentrations, while the fluorine concentrations in soils with CaO amendments were similar following treatment. This suggests that fluorine emissions from smoldering treatment of PFAS are captured by the presence of the calcium ion (Ca2+). Using new analytical methods, we better characterized the mass balance of the system. These lab results were carried out in a pilot study using soils from a PFAS-impacted site. Two large-scale tests treating 10 m3 of soil were completed. Results of the large-scale smoldering tests agreed with the results from the lab phase. The results from both phases provide a greater understanding of the fate of PFAS when it is treated by smoldering and detail the first large-scale demonstration of smoldering treatment for PFAS-impacted soils.

Per- and polyfluoroalkyl substances (PFAS) pose a significant challenge for water treatment facilities facing strict regulatory standards. Granular activated carbon (GAC) adsorption is effective for PFAS removal, but media exhaustion and replacement can be costly, highlighting the need for innovative GAC regeneration methods. While thermal reactivation of GAC can eliminate adsorbed PFAS, it requires high temperatures and is mainly feasible for large-scale media users. This study investigates spent GAC regeneration by hydrothermal alkaline treatment (HALT), which applies subcritical water (e.g., 350 °C, 16.5 MPa) amended with strong base (e.g., NaOH) to destroy PFAS. Previous research indicates that HALT successfully degraded and defluorinated PFAS while maintaining GAC surface area and equilibrium adsorption capacity. This study presents data from rapid small-scale column tests (RSSCTs) demonstrating effective removal of long-chain PFAS by a HALT-treated spent GAC sample collected from a long-term PFAS treatment field pilot study (BV50 > 50,000 for PFOS, PFHxS, and PFNA). HALT-treated virgin GAC and untreated virgin GAC evaluated using RSSCTs exhibited similar PFAS breakthrough behavior, with comparable overall PFAS removal to the HALT-treated spent GAC. Physisorption measurements revealed that HALT recovers GAC pore surface area lost during field-use. Surface chemical characterization techniques indicated mostly similar surface composition and functional groups in virgin and HALT-treated GAC, with limited change in the carbon structure following HALT and differences between virgin and field-spent samples. Analyses of reactor liquid products, media mass loss, and NaOH neutralization by GAC also provided evidence for removal of adsorbed non-target organic matter and possible GAC surface renewal by carbon gasification reactions occurring in parallel with PFAS destruction, analogous to surface carbon burn-off that occurs during high-temperature thermal reactivation. Retention of adsorbed metal ions that accumulated on the spent GAC during field testing may be responsible for enhanced adsorption behavior observed for some PFAS following HALT regeneration. Results indicate that HALT can enable reuse of spent GAC, potentially alleviating the high demand for virgin media in PFAS treatment processes.

Granular activated carbon (GAC) has been widely used to remove per- and polyfluoroalkyl substances (PFAS) from contaminated drinking water. The spent GAC can be thermally destroyed or regenerated for reuse. To understand how innovations in thermal treatment can reduce environmental impact of PFAS-laden GAC, we performed a life cycle assessment (LCA) of the thermal oxidation and pyrolysis of perfluorooctane sulfonic acid (PFOS) loaded onto GAC with and without the use of calcium additives. The functional unit for the study was 1 kg of clean GAC, and the system boundary included transportation, thermal oxidation or regeneration and reuse of GAC, and treatment of the waste byproducts. Two underlying assumptions were made based on prior research: (1) the regeneration and post-performance of the GAC was 100 % for all scenarios, and (2) the additive eliminated volatile organic fluorine (VOF) products of incomplete destruction (PIDs) and captured hydrofluoric acid (HF). Without an additive, the LCA indicated that regeneration and reuse have an overall lower environmental impact than thermal oxidation. The highest impact comes from the need for an afterburner to treat the VOF. Using hydrated lime as an additive decreases the temperature and time required for mineralization of PFAS, reducing the environmental impact in all categories. This is attributed to not needing post-processes to handle VOF and HF. The results underscore the importance of choosing the appropriate management practice for PFASladen GAC, with the goal of reducing environmental impacts while maximizing the destruction and mineralization efficiency of PFAS.

In February 2023, a train derailment in Ohio caused a chemical spill and fires releasing contaminants into the air, soil, waterways, and buildings. The authors conducted a rapid response which included six field investigations and bench-scale experiments to understand the chemical identity, fate, and exposure pathways after the evacuation order was lifted. Multiple buildings were chemically contaminated and silicone wristband products inside a commercial building were found to have adsorbed derailment-related chemicals. The indoor air of this commercial building was found to be contaminated for 4.5 months after the derailment. Derailment chemicals were also found on building exteriors 5 weeks after the incident. Railcar chemicals were detected in the nearby creeks. Cleanup activities (sorbent pads, aerators) as well as creek hydraulic and environmental conditions influenced chemical fate in creeks. Creek mechanical aeration activities prompted VOC emission that contributed to human exposures and vapor intrusion. Atmospheric modeling revealed that the chemical plumes extended beyond the evacuation zone. Water was a consequential media associated with contaminant transport and human exposures found in the present study. Because the complexity, magnitude, and health threats posed to the community were not matched by efforts employed by the responding organizations, the population experienced continued exposures for months; workers as well as town visitors also experienced health symptoms. This study revealed unaddressed human exposure pathways. Also identified were crucial gaps requiring improved decision-making and technologies. Recommendations to better protect human health and the environment before and during a response to chemical incidents are provided. In February 2023, a train derailment in Ohio caused a chemical spill and fires releasing contaminants into the air, soil, waterways, and buildings.

With drinking water regulations forthcoming for per- and polyfluoroalkyl substances (PFAS), the need for cost-effective treatment technologies has become urgent. Adsorption is a key process for removing or concentrating PFAS from water; however, conventional adsorbents operated in packed beds suffer from mass transfer limitations. The objective of this study was to assess the mass transfer performance of a porous polyamide adsorptive membrane for removing PFAS from drinking water under varying conditions. We conducted batch equilibrium and dynamic adsorption experiments for perfluorooctanesulfonic acid, perfluorooctanoic acid, perfluorobutanesulfonic acid, and undecafluoro-2-methyl-3-oxahexanoic acid (i.e., GenX). We assessed various operating and water quality parameters, including flow rate (pore velocity), pH, ionic strength (IS), and presence of dissolved organic carbon. Outcomes revealed that the porous adsorptive membrane was a mass transfer-efficient platform capable of achieving dynamic capacities similar to equilibrium capacities at fast interstitial velocities. The adsorption mechanism of PFAS to the membrane was a mixture of electrostatic and hydrophobic interactions, with pH and IS controlling which interaction was dominant. The adsorption capacity of the membrane was limited by its surface area, but its site density was approximately five times higher than that of granular activated carbon. With advances in molecular engineering to increase the capacity, porous adsorptive membranes are well suited as alternative adsorbent platforms for removing PFAS from drinking water.

A portable toilet manufacturer in northwest Indiana (USA) released polyethylene microplastic (MP) pollution into a protected wetland for at least three years. To assess the loads, movement, and fate of the MPs in the wetland from this point source, water and sediment samples were collected in the fall and spring of 2021–2023. Additional samples, including sediment cores and atmospheric particulates, were collected during the summer of 2023 from select areas of the wetland. The MPs were isolated from the field samples using density separation, filtration, and chemical oxidation. Infrared and Raman spectroscopy analyses identified the MPs as polyethylene, which were quantified visually using a stereomicroscope. The numbers of MPs in 100 mL of the marsh water closest to the source ranged from several hundred to over 400,000, while the open water samples contained few microplastics. Marsh surface sediments were highly contaminated with MPs, up to 18,800 per 30.0 g dry mass (dm), compared to core samples in the lower depths (>15 cm) that contained only smaller MPs (<200 µm), numbering 0–480 per 30.0 g (dm). The wide variations in loads of MP contaminants indicate the influence of numerous factors, such as proximity to the point source pollution, weather conditions, natural matter, and pollution sinks, namely sediment deposition. As proof of concept, we demonstrated a novel remediation method using these real-world samples to effectively agglomerate and remove MPs from contaminated waters.

This study conducts a systematic investigation of the creation and optimization of a rutin-loaded transethosome intended for topical use. The formulation's characteristics were thoroughly assessed for vesicle size (160.45 +/- 1.98 nm), polydispersity index (0.235 +/- 0.067), and zeta potential (-22.89 mV), with an entrapment efficiency and drug loading of 89.99 +/- 1.55% and 8.9 +/- 2.11%, respectively, and found to have a spherical shape by the use of transmission electron microscopy. The conversion to a gel suitable for application on the skin was carried out. The drug release form Opt-RUT-TE formulation (73.61 +/- 2.55%) was significantly higher than that of release form RUT-suspension (34.52 +/- 1.19%). The drug that permeated the skin from Opt-RUT-TEG (935.25 +/- 10.49 mu g/cm(2)) was significantly higher than the permeability from RUT-Suspension gel (522.57 +/- 6.79 mu g/cm(2)). Notably, tape stripping analysis revealed that the Opt-RUT-TE gel effectively penetrated the skin layers, with a higher concentration observed in the epidermis-dermis than in the RUT-suspension gel. The transethosomal gel exhibited favorable characteristics, highlighting its capacity to efficiently permeate the skin and suppress the growth of microorganisms, and Opt-RUT-TEG showed a higher microorganism inhibition zone (Gram-positive bacteria) than that of RUT-suspension gel. The investigation highlights the significant therapeutic possibilities of rutin in a transethosomal gel formulation for treating dermatological diseases by improving skin permeability and exhibiting antibacterial effects.

Sunlight irradiation is the predominant process for degrading plastics in the environment, but our current understanding of the degradation of smaller, submicron (<1000 nm) particles is limited due to prior analytical constraints. We used infrared photothermal heterodyne imaging (IR-PHI) to simultaneously analyze the chemical and morphological changes of single polystyrene (PS) particles (similar to 1000 nm) when exposed to ultraviolet (UV) irradiation (lambda = 250-400 nm). Within 6 h of irradiation, infrared bands associated with the backbone of PS decreased, accompanied by a reduction in the particle size. Concurrently, the formation of several spectral features due to photooxidation was attributed to ketones, carboxylic acids, aldehydes, esters, and lactones. Spectral outcomes were used to present an updated reaction scheme for the photodegradation of PS. After 36 h, the average particle size was reduced to 478 +/- 158 nm. The rates of size decrease and carbonyl band area increase were -24 +/- 3.0 nm h(-1) and 2.1 +/- 0.6 cm(-1) h(-1), respectively. Using the size-related rate, we estimated that under peak terrestrial sunlight conditions, it would take less than 500 h for a 1000 nm PS particle to degrade to 1 nm.

This study is the first comprehensive investigation into the extent of microplastic pollution in Frenchman Bay, ME, which is a semi-sheltered coastal bay with some freshwater input making it an ideal location to study the land-sea connection of microplastic pollution. Two sampling campaigns were coordinated for this study, and during the first one, 323 fibers were identified from water samples collected on a weekly basis from the Bay from July through October of 2022. The chemical compositions of a subset of these samples were determined by micro-Raman analysis, identifying the types of microplastic fibers (MPFs) in the Bay. In total, an average of 1.8 fibers/L were found among all sampling locations, from which it was estimated that up to 400 billion MPFs may reside in the upper one meter of Frenchman Bay. A complementary sampling campaign was organized to investigate potential land-based sources of MPF pollution. Grab samples were collected during six sampling events at a variety of rural and urban locations surrounding the Bay. The highest microplastic concentration was from a culvert during a storm, releasing an average of 15.3 fibers/L directly into Frenchman Bay. It is suspected that the MPFs enter Frenchman Bay from regional land-based sources, as the size of the microplastics decreases as the sampling location becomes farther from land, and it appears the color fades in relation to distance from land. This study is the first systematic microplastic sampling campaign of the Bay and can set an example for similar studies in estuary systems that are investigating the land-sea connection.

The fate and transport of nanoparticles (NPs) in streams is critical for understanding their overall environmental impact. Using a unique field-scale stream at the Notre Dame-Linked Experimental Ecosystem Facility, we investigated the impact of biofilms and the presence of dissolved organic matter (DOM) on the transport of titanium dioxide (TiO2) NPs. Experimental breakthrough curves were analyzed using temporal moments and fit using a mobile-immobile model. The presence of biofilms in the stream severely reduced the transport of the TiO2 NPs, but this was mitigated by the presence of DOM. Under minimal biofilm conditions, the presence of DOM increased the mass recovery of TiO2 from 4.2% to 32% for samples taken 50 m downstream. For thriving biofilm conditions only 0.5% of the TiO2 mass was recovered (50 m), but the presence of DOM improved the mass recovery TiO2 to 36%. The model was suitable for predicting early, peak, tail, and truncation time portions of the breakthrough curves, which attests to its ability to capture a range of processes in the mobile and immobile domains of the stream. The model outcomes supported the hypothesis that DOM changed the interaction of NP-biofilm from an irreversible to a reversible process. Collectively, these outcomes stress the importance of considering biogeological complexity when predicting the transport of NPs in streams.

Per- and polyfluoroalkyl substances (PFASs) are fluorinated organic chemicals that are concerning due to their environmental persistence and adverse human and ecological effects. Remediation of environmental PFAS contamination and their presence in consumer products have led to the production of solid and liquid waste streams containing high concentrations of PFASs, which require efficient and cost-effective treatment solutions. PFASs are challenging to defluorinate by conventional and advanced destructive treatment processes, and physical separation processes produce waste streams (e.g., membrane concentrate, spent activated carbon) requiring further post-treatment. Incineration and other thermal treatment processes are widely available, but their use in managing PFAS-containing wastes remains poorly understood. Under specific operating conditions, thermal treatment is expected to mineralize PFASs, but the degradation mechanisms and pathways are unknown. In this review, we critically evaluate the thermal decomposition mechanisms, pathways, and byproducts of PFASs that are crucial to the design and operation of thermal treatment processes. We highlight the analytical capabilities and challenges and identify research gaps which limit the current understanding of safely applying thermal treatment to destroy PFASs as a viable end-of-life treatment process.

A key challenge for addressing micro- and nanoplastics (MNPs) in the environment is being able to characterize their chemical properties, morphologies, and quantities in complex matrices. Current techniques, such as Fourier transform infrared spectroscopy, provide these broad characterizations but are unsuitable for studying MNPs in spectrally congested or complex chemical environments. Here, we introduce a new, super-resolution infrared absorption technique to characterize MNPs, called infrared photothermal heterodyne imaging (IR-PHI). IR-PHI has a spatial resolution of ∼300 nm and can determine the chemical identity, morphology, and quantity of MNPs in a single analysis with high sensitivity. Specimens are supported on CaF2 coverslips under ambient conditions from where we (1) quantify MNPs from nylon tea bags after steeping in ultrapure water at 25 and 95 °C, (2) identify MNP chemical or morphological changes after steeping at 95 °C, and (3) chemically identify MNPs in sieved road dust. In all cases, no special sample preparation was required. MNPs released from nylon tea bags at 25 °C were fiber-like and had characteristic IR frequencies corresponding to thermally extruded nylon. At 95 °C, degradation of the nylon chemical structure was observed via the disappearance of amide group IR frequencies, indicating chain scission of the nylon backbone. This degradation was also observed through morphological changes, where MNPs altered shape from fiber-like to quasi-spherical. In road dust, IR-PHI analysis reveals the presence of numerous aggregate and single-particle (<3 μm) MNPs composed of rubber and nylon.