The plasma-plastic paradox: breaking down plastics, building up risk?

1 Introduction

Microplastics (MPs) are now recognized as pervasive pollutants across aquatic, terrestrial, and atmospheric compartments, with documented occurrence from wastewater effluents to the deep sea and even remote mountain environments (Van Cauwenberghe et al., 2013; Free et al., 2014; An et al., 2024; Lebepe et al., 2025). Their small size, high surface-area-to-volume ratio, and propensity to sorb co-contaminants such as pharmaceuticals and persistent organic pollutants (Wisniewski et al., 2025; Al-Emran and Nayem, 2025), make them particularly challenging to remove and to regulate, especially in large water volumes and heterogeneous matrices.

Conventional approaches, including filtration, coagulation–flocculation, flotation, and adsorption, can achieve significant removal in some settings, but are often energy-intensive, sensitive to fouling, or ineffective against the smallest or most buoyant fractions, and they rarely achieve permanent destruction of the polymer matrix (Amparán et al., 2025).

Plasma, often described as the fourth state of matter, is a partially ionized gas comprising free electrons, positive and negative ions, reactive neutral species and photons, generated when sufficient energy is supplied to strip electrons from a gas's constituent atoms or molecules. In thermal plasmas, such as those used in arc welding or plasma torches, electrons and heavier particles reach thermal equilibrium at temperatures of several thousand kelvin. Cold or non-thermal plasma instead operates far from this equilibrium: energetic electrons (with effective temperatures equivalent to several electron-volts) drive ionization and dissociation reactions, while the much heavier ions and neutral gas molecules remain close to ambient temperature. This non-equilibrium is what allows cold plasma to generate a highly reactive chemical environment without substantially heating the treated medium. The resulting reactive oxygen and nitrogen species (RONS-e.g. hydroxyl radicals, ozone, hydrogen peroxide, atomic oxygen and reactive nitrogen oxides), together with UV photons, ions and electrons, interact with the polymer surface to drive oxidation, chain scission, surface functionalization and, under sufficiently intensive treatment, mineralization of the carbon backbone to CO₂/CO_*x* (Reyna Martínez, 2018; Aggelopoulos, 2022; Das et al., 2022; Pequeno et al., 2026). However, the emerging literature reveals that CP interacts with microplastics in multiple, sometimes opposing ways. Some studies demonstrate partial degradation or high mass-loss in soil or catalytic systems, others show mainly surface oxidation and agglomeration in water, and yet others use cold plasma as an accelerated aging tool to probe degradation products and toxicity rather than as a remediation technology (Liu et al., 2023; Sima et al., 2024b; Dimic-Misic et al., 2024; Velasquez et al., 2024; Sima et al., 2024a; Wypart-Pawul et al., 2025).

Because plasma-induced transformation can either reduce or redistribute environmental risk depending on the balance between polymer abatement, by-product formation, mobility and toxicity, “remediation” should not be used as a synonym for any detectable change in polymer properties. It is therefore essential to distinguish between: (i) physical removal or separation, such as aggregation or flotation-enhanced capture; (ii) partial degradation, including surface oxidation, chain scission and mass loss; (iii) fragmentation, which may reduce particle size without reducing particle number or risk; and (iv) mineralization, where polymer carbon is converted primarily to CO₂ or CO_*x* (Graphical Abstract).

Direct evidence on cold plasma-microplastic interactions in seawater or marine sediments remains minimal, so this perspective draws primarily on freshwater, soil and waste-stream studies, treated here as mechanistically informative for marine and coastal applications while flagging where marine water chemistry is expected to change outcomes. It examines cold plasma within a unified framework that evaluates it simultaneously as a remediation technology and as a process that transforms, mobilizes, and potentially minimizes microplastic-associated environmental risks.

2 Mapping the emerging literature

Relevant literature was identified through a targeted narrative search. This article synthesizes and interprets the literature to propose a conceptual framework rather than provide exhaustive, protocol-driven coverage. Searches were conducted in Google Scholar, Web of Science, Scopus, and PubMed/MEDLINE using combinations of (“cold plasma” OR “non-thermal plasma” OR “plasma-activated water”) AND (“microplastic^*” OR “plastic^*” OR “polymer”). No start-date restriction was applied, and the search covered all available literature up to 4 May 2026. English-language articles were included if they were directly relevant to cold plasma, non-thermal plasma, or plasma-activated water in the context of microplastics, plastic particles, or polymers associated with microplastic pollution. The direct microplastic-plasma remediation literature remains limited, while the broader plastic-plasma literature provides partially transferable evidence on surface modification, degradation and carbon conversion. The literature can be grouped into four partially overlapping categories: (i) direct remediation in water, (ii) remediation in soil or solid matrices, (iii) plasma accelerated aging and degradation product analysis, and (iv) studies where microplastics are “bystanders” during plasma treatment of other pollutants. Each category provides different pieces of evidence about mechanisms, performance, and risk.

Studies were assigned to “direct remediation in water” when plasma (direct discharge or plasma-activated water) was applied to microplastics suspended in an aqueous matrix with removal, degradation or surface modification of the particles as a stated aim. Studies were assigned to “remediation in soil or solid matrices” when the treated matrix was soil, sediment or another solid substrate. Studies were assigned to “plasma-accelerated aging and degradation-product analysis” when plasma exposure was used explicitly as a weathering or aging tool to generate and characterize degradation products or altered particle properties, rather than as a treatment intended to remove or destroy the polymer. Studies were assigned to the “bystander” category when microplastics were present in the treated system (e.g., as a sorbent, vector or co-contaminant) but were not the primary object of plasma treatment or removal. Categories were treated as partly overlapping because several studies provide evidence relevant to more than one category; such studies are cited under each relevant category rather than assigned to a single one.

For direct remediation in water, one of the first explicit studies is the work by Velasquez et al. (2024), who treated polypropylene (PP) and low density polyethylene (LDPE) microplastics suspended in water using atmospheric dielectric barrier discharge (DBD). In 30 min of treatment, they reported mass losses of 1.4%−11.3%, with PP showing greater weight reduction than LDPE, and mixtures of oxygen and nitrogen as feed gases outperforming single gas plasmas.

Surface analysis revealed cracks, pits, and a marked increase in the carbonyl index of PP, indicating surface oxidation and hydrolytic degradation pathways (Velasquez et al., 2024). This study established atmospheric cold plasma as a proof of concept tool for affecting microplastics in aqueous suspension, but also highlighted that under realistic treatment times, degradation was partial and confined largely to the surface. A recent study used a custom cold plasma reactor to treat melamine resin microplastics (~2 μm) suspended in water, achieving a size reduction to ~119 nm and 43% mass loss after 30 min. Transmission electron microscopy (TEM) analysis showed smooth microspheres transforming into porous nanofragments (68–119 nm), consistent with oxidative chain scission and surface etching by plasma generated •OH, O3 and H₂O₂ (Bexeitova et al., 2026). However, because this process also generated nanometric fragments, it should not be interpreted as remediation solely on the basis of size reduction or mass loss unless residual particle number, nanoplastics formation and post-treatment toxicity are also assessed. Another study applied atmospheric DBD cold plasma directly to polyvinyl chloride (PVC), polystyrene (PS) and PP microplastics suspended in water, using real time CO₂ monitoring to quantify mineralization. Using oxygen instead of atmospheric air markedly enhanced degradation, with PVC showing the highest CO₂ release and PP the lowest reactivity, while scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and Raman analyses revealed polymer specific surface oxidation and backbone damage under plasma treatment (Iervolino and Vaiano, 2026). Plasma-activated water (PAW) has also been explored as an indirect route for microplastic degradation in aquatic systems. A 2026 study on polystyrene microplastics reported ≈80% removal (particle counts) within 2 h, and mechanistic analysis combining in situ electron paramagnetic resonance (EPR), optical emission spectroscopy and density functional theory (DFT) identified hydroxyl radical attack at benzylic sites as the dominant initiation step for backbone scission. Supporting total organic carbon (TOC), molecular-weight and gas chromatography-mass spectrometry (GC-MS) data showed progressive surface roughening, chain scission and formation of low-molecular-weight oxidation products, while a life-cycle assessment indicated a lower carbon footprint than photocatalysis or activated carbon for comparable treatment, and time-resolved ecotoxicity tests revealed an initial increase in effluent toxicity followed by a decline as treatment proceeded, with some products acting as substrates for microbial growth (Yuan et al., 2026).

Studies in soil and solid matrices are even more scarce. A 2023 study treating landfill soil containing polyethylene (PE), PP, PS and PVC microplastics (50–1,500 μm) with a coaxial DBD plasma system achieved up to 96.5% mass loss in 30 min using air, with an energy efficiency of 19.03 mg kJ⁻¹ (Sima et al., 2023). Then, focusing on polystyrene microplastics in soil, the same group obtained 98%−99% degradation in 60 min, with most carbon converted to CO_*x*, and later showed that adding a Hopcalite stage in a two step plasma assisted catalytic system yielded almost complete conversion to CO₂ [α(CO₂) ≈ 98%−99%] over repeated cycles (Sima et al., 2024a). These soil and gas-solid configurations indicate that cold plasma can approach total mineralization for certain polymers in highly controlled reactors.

Beyond direct degradation, CP has also been explored as a pre-treatment to enhance subsequent biodegradation. Chen et al. (2024) showed that cold atmospheric plasma pre-treatment increased the surface hydrophilicity, roughness and microbial colonization of high-density polyethylene (HDPE) and PS samples during fungal incubation. The effect was stronger for HDPE, where modest weight loss and changes in hydrophobicity were observed, whereas PS showed no measurable gravimetric weight loss but clear surface corrosion. This supports the use of plasma as a surface-activation strategy for biodegradation, although the study used polymer films and foam samples rather than environmentally recovered microplastic particles, and should therefore be interpreted as supporting evidence rather than direct proof of microplastic remediation.

Another application of cold plasma is as an accelerated aging tool to probe degradation products and toxicity. A 2024 study aged PP and polyethylene terephthalate (PET) microplastics with cold plasma and then analyzed gas, particle and liquid phases, finding surface yellowing, higher carbonyl index and crystallinity, and complex mixtures of ketones, esters, acids, alcohols and aromatic hydrocarbons, demonstrating that plasma aging can generate potentially harmful organic transformation products (Cai et al., 2024). Du et al. (2025) used plasma induced aging of PS and PVC microplastics to study mercury behavior, showing that plasma aged particles, despite the limited size change for PS, became more hydrophilic and more negatively charged, developed additional O and N containing functional groups, and consequently exhibited markedly higher Hg²⁺ adsorption and even partial reduction of Hg²⁺ to Hg⁺. Zhou et al. (2022) showed that plasma aged PS, PVC, PP and PE not only developed cracked, oxidized surfaces but also released 4–14 mg L⁻¹ of humic like dissolved organic carbon and produced substantial chlorinated disinfection by products, mainly haloacetic acids up to ~1.2 mg L⁻¹.

Several cold plasma studies treat co contaminants in the presence or context of microplastics, but almost none analyze both components in detail. Wypart-Pawul et al. 2025 explicitly combined PE microplastics with pharmaceuticals, showing that CP induced strong MP agglomeration while removing >98%−99.99% of diclofenac, sulfamethoxazole and trimethoprim from MP bearing waters. Du et al. (2025) and Zhou et al. (2022) used plasma primarily to study metal transport (Hg²⁺) and disinfection by product (DBP) formation, respectively, but demonstrated that plasma aged MPs can become stronger metal sorbents and significant DBP precursors, rather than being neutralized contaminants.

Beyond these, implementation oriented reviews and experimental papers on cold plasma disinfection and pollutant removal in water frequently mention microplastics as emerging co contaminants or future targets, but do not include MPs in the actual experimental design or monitoring, focusing instead on pathogens, per- and polyfluoroalkyl substances (PFAS), pharmaceuticals or dyes (Gururani et al., 2021; Aggelopoulos, 2022; Foster and Garcia, 2022; Joshi et al., 2022; Lan et al., 2024; Xia et al., 2025). This means that, while there is growing knowledge on plasma-based bacterial inactivation and pollutant removal, data are scarce on both how these processes behave when microplastics are simultaneously present as sorbents and vectors, and on whether plasma conditions optimized for pathogen control inadvertently mobilize or transform MPs in ways that alter risk, highlighting a clear limitation and a knowledge gap.

Bulk plastic-waste plasma conversion is informative from an engineering and carbon-conversion perspective, but it should not be treated as direct evidence for dispersed microplastic remediation. Plasma and related thermochemical processes are already being deployed or modeled for concentrated plastic-waste valorization, including the conversion of mixed plastics into syngas, hydrogen and fuels. High-temperature thermal plasma gasification of plastic fractions in municipal solid waste has been reported to reach overall energy-output efficiencies around 80%, with substantial recovery of pyrolysis oils and favorable economic indicators such as short payback times (Rida Galaly et al., 2024). These studies are therefore best used to define boundary conditions for concentrated plastic streams, not to infer performance in dilute aquatic, sedimentary, wastewater or marine matrices.

Modeling of non-thermal plasma gasification integrated into waste to energy plants likewise suggests that, if cold gas efficiency comparable to thermal plasma can be achieved, non-thermal plasma could reduce exergy losses relative to conventional incineration based cycles (Kwon and Im, 2022). Recent reviews on plasma gasification and pyrolysis plasma/catalytic reforming highlight the potential to turn post-consumer plastics into hydrogen, syngas or energy storage materials, but emphasize that these routes are viable only when plastics are highly concentrated and that energy demand and flue gas management remain critical constraints (Aminu et al., 2020; Tang et al., 2023; Tabu et al., 2024; Rida Galaly et al., 2024; Yun et al., 2025; Diao et al., 2026).

A key limitation across these studies is that reported endpoints are not interchangeable, as particle-count reduction may reflect aggregation, sedimentation or analytical loss rather than polymer destruction, mass loss does not necessarily indicate mineralization, size reduction can generate nanoplastic fragments, and CO₂ release captures only part of the carbon balance unless gas, liquid and residual particle phases are jointly quantified. Therefore, apparent treatment efficiencies should be interpreted cautiously unless supported by carbon-normalized mass balances, particle-size distributions, residual polymer characterization and transformation-product analysis. These interpretation challenges are compounded by analytical artifacts common in microplastic studies, including particle loss during recovery, aggregation-driven undercounting, oxidation-induced changes in polymer spectra, and incomplete detection of submicrometric fragments.

3 Cold plasma at the remediation-risk interface

Taken together, the studies summarized in the previous section show that cold plasma sits at the interface between remediation and risk transformation, and does not act on microplastics in a single, simple way. Direct water-phase treatments with atmospheric DBD or PAW are typically reported in terms of mass loss, particle removal and surface functionalization, with evidence of partial degradation or fragmentation for PP, LDPE, PS and melamine-resin MPs over treatment times of tens of minutes. In contrast, soil and catalytic gas-solid systems have reported near-complete mineralization for selected polymers, especially concentrated PS feeds, under highly controlled reactor conditions (Sima et al., 2023; Velasquez et al., 2024; Sima et al., 2024a; Iervolino and Vaiano, 2026; Bexeitova et al., 2026).

At the same time, plasma assisted biodegradation and aging studies demonstrate that the same treatments can render plastics more biologically labile, increase their capacity to bind and transform metals, and turn them into sources of dissolved organic matter and disinfection by product precursors, rather than simply eliminating them as pollutants (Cai et al., 2024; Chen et al., 2024; Du et al., 2025). To capture this duality in a way that is useful for implementation in marine-relevant systems, we propose evaluating plasma–microplastic configurations along four intertwined axes (Table 1). The first is abatement, which should be expressed not only as percentage mass loss or particle count reduction, but also as absolute load removed per unit energy input and reactor footprint. Current works largely report relative reductions without energy-normalized metrics, even in cases where mineralization appears nearly complete (Velasquez et al., 2024; Sima et al., 2024a; Iervolino and Vaiano, 2026; Bexeitova et al., 2026). The second axis is degradation products, spanning gas, liquid and particle phases. This should include low-molecular-weight organics, dissolved organic carbon (DOC) release, disinfection by-product formation, plastic additives and other formulation-derived chemicals, since polymer identity alone may not capture the full transformation-product profile of real-world microplastics. Only a handful of studies have systematically addressed these outputs, despite clear evidence that plasma can generate complex mixtures of ketones, esters, acids, alcohols, aromatic hydrocarbons and chlorinated DBPs from aged microplastics (Zhou et al., 2022; Cai et al., 2024). The third axis is mobility, encompassing how plasma induced changes in size, surface charge and aggregation state affect microplastic transport through porous media, sediments and engineered units. Existing work shows that plasma can both aggregate particles (facilitating separation in engineered systems) and increase their mobility in saturated porous media, and that plasma aged MPs can act as enhanced sorbents and vectors for metals such as Hg²⁺ and Cd²⁺. Yet these outcomes are rarely quantified in terms of breakthrough behavior or integrated into risk assessments (Wypart-Pawul et al., 2025; Ji et al., 2025; Du et al., 2025). The fourth proposed axis concerns ecotoxicological effects, which remain poorly characterized in the current literature. Existing studies mostly stop at physicochemical characterization, product identification, or transport behavior, and do not track acute or chronic biological responses to plasma-treated microplastics across marine organisms, making ecological risk the least resolved dimension of the field.

Table 1. Proposed four-axis framework for evaluating cold plasma treatment of microplastics at the remediation–risk interface.

Seen through this four-axis lens, the current microplastics–plasma literature is revealing precisely because of what it omits. Most studies score strongly on at most one or two axes, typically abatement and qualitative surface chemistry, while leaving degradation products, mobility and ecotoxicology either unquantified or inferred from limited proxies. No study currently combines energy-normalized abatement data, multi-phase product characterization, mobility metrics and biological endpoints in a single experimental design. In addition, very few studies evaluate cold plasma-microplastic interactions in seawater or estuarine matrices, and this gap is consequential for each of the four axes proposed above. For instance, high chloride and bromide concentrations in seawater scavenge hydroxyl radicals and ozone, which is likely to lower effective oxidant dose and alter abatement kinetics relative to freshwater. The same halides can react with plasma-generated reactive species to form reactive halogen species, raising the possibility of halogenated degradation products beyond those already reported in freshwater systems (e.g., the haloacetic acids described by Zhou et al. 2022), directly relevant to the degradation-products axis. Seawater's high ionic strength is also expected to compress the electrical double layer around suspended particles, promoting aggregation differently than in freshwater and changing how treated microplastics partition between the water column, sediment and biofilm-coated surfaces (the mobility axis). Finally, marine and estuarine organisms experience these transformations under co-occurring salinity stress, so ecotoxicological outcomes cannot be reliably extrapolated from freshwater or soil toxicity data. Testing under marine-relevant conditions is, in our view, the single most important step for establishing whether cold plasma is compatible with marine and ocean sustainability applications specifically.

4 Discussion and proposal of a new research agenda

The number of truly microplastic-focused cold plasma studies is still small, but they collectively open a wide conceptual space. There is an urgent need for systematic experiments that cover different polymer types, particle sizes, and degrees of weathering or biofouling, using both direct plasma and PAW configurations. These configurations should be evaluated separately, since they differ in reactive-species lifetimes, contact geometry, energy transfer, scalability and sensitivity to water chemistry. These studies should report not only mass loss or particle counts, but also comprehensive degradation-product profiles, mobility changes in sediments and porous media, and toxicity to marine organisms representing different trophic levels. In parallel, engineering and techno-economic analyses are needed to determine whether cold plasma-based modules can realistically compete with or complement existing microplastic removal technologies. In practical implementation, cold plasma is more plausible as a polishing or transformation-control step applied to pre-concentrated streams, retained solids, membrane concentrates or reactor recirculation loops than as a stand-alone treatment for large volumes of dilute environmental water.

Life-cycle assessments and cost analyses, such as those already performed for plasma-activated water systems, should be extended to microplastic-specific scenarios and compared against pressure-driven membranes, electro-coagulation, and electrochemical oxidation. The field would benefit from closer integration between environmental engineers, microplastic ecologists, microbiologists, ecotoxicology experts and policymakers. As regulations for microplastics monitoring and removal in drinking water, wastewater, and marine environments are developed, early engagement can help define realistic performance criteria and avoid technologies that perform well on isolated metrics but worsen overall risk. Any future demonstration of “microplastics remediation by cold plasma” should report a minimum set of indicators spanning the four axes outlined above, and any claim of remediation should be supported by evidence of net risk reduction, not only by evidence of altered polymer morphology or reduced particle counts. In practical terms, future studies should be designed so that a positive result on one axis cannot mask deterioration on another, for example high particle-count removal accompanied by nanoplastic formation, toxic by-products or increased transport potential. This would establish a baseline for assessing whether cold plasma can become a component of future microplastic treatment trains, and under which conditions it delivers net environmental benefit rather than merely transforming polymer form or redistributing risk.

Although the current evidence base is dominated by freshwater suspensions, soils, polymer aging studies, and concentrated waste streams, the marine context remains important because microplastics ultimately accumulate in estuarine and oceanic systems. Future studies should therefore evaluate cold plasma and plasma-activated water under seawater-relevant conditions, where salinity, halides, natural organic matter, suspended solids, and biofilms may alter reactive-species lifetimes, degradation pathways, particle mobility, and ecotoxicological outcomes. In practical terms, cold plasma is more plausibly applied to pre-concentrated marine-derived streams, retained solids, or contained treatment matrices than to open marine waters. Until such seawater- and estuary-specific testing is performed, claims of marine microplastic remediation by cold plasma should be considered preliminary, because the technology may alter particle form without ensuring a net reduction in environmental risk.

Generative AI statement

The author(s) declared that Generative AI was used in the creation of this manuscript. Generative AI was used to assist with English language editing and concept summarization. The author(s) reviewed and verified all content.

Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.

Publisher's note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

Footnotes

Edited by: Jesus Gago, Spanish Institute of Oceanography (IEO), Spain

Reviewed by: Bariş Kiriş, Istanbul University-Cerrahpaşa, Türkiye