Cold Plasma-Induced Changes in Polyethylene Particles and Their Binding Affinity to Selected Pharmaceuticals

Academic Editor: Vasilios Sakkas Received: 4 August 2025 Revised: 10 September 2025 Accepted: 11 September 2025 Published: 16 September 2025 Citation: Wypart-Pawul, A.; Karwowska, B.; Caban, R.; Grobelak, A. Cold Plasma-Induced Changes in Polyethylene Particles and Their Binding Affinity to Selected Pharmaceuticals. Molecules 2025,30, 3756. https://doi.org/10.3390/ molecules30183756 Copyright: © 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/). Article Cold Plasma-Induced Changes in Polyethylene Particles and Their Binding Affinity to Selected Pharmaceuticals Aleksandra Wypart-Pawul 1, Beata Karwowska 1, Renata Caban 2and Anna Grobelak 1,* 1Faculty of Infrastructure and Environment, Cz˛estochowa University of Technology, 42201 Cz˛estochowa, Poland; [email protected] (A.W.-P.); [email protected] (B.K.) 2Faculty of Production Engineering and Materials Technology, Cz˛estochowa University of Technology, 42201 Cz˛estochowa, Poland; [email protected] *Correspondence: anna.gr[email protected] Abstract Environmental contamination with microplastics and trace pharmaceuticals is an increasing ecological and health concern. This study aimed to investigate the effects of lowtemperature cold plasma on polyethylene (PE) microplastic particles and to assess the potential for degradation of pharmaceuticals adsorbed onto their surfaces. Two types of PE samples were prepared: suspended in distilled water and in treated wastewater. All samples were exposed to cold plasma. In the second stage, PE particles were saturated with selected pharmaceuticals (diclofenac, sulfamethoxazole, trimethoprim) and then subjected to plasma treatment. Pharmaceutical concentrations were measured using high-performance liquid chromatography (HPLC). Particle morphology was analyzed via light microscopy (after Nile red staining) and scanning electron microscopy (SEM). The results showed that cold plasma treatment leads to agglomeration of PE particles, with the extent increasing with longer plasma exposure time. Pharmaceuticals adsorbed to the PE surface in the range of 20–70% of the applied dose. Cold plasma demonstrated the ability to remove pharmaceutical contaminants, particularly diclofenac (>98%), sulfamethoxazole (99.99%) and trimethoprim (>98%). These findings indicate that cold plasma has promising potential as a supportive technology for removing both microplastics and pharmaceutical residues from wastewater and aquatic environments. Keywords: cold plasma; polyethylene microplastics; pharmaceutical residues; sorption; environmental chemistry; advanced oxidation 1. Introduction The presence of microplastics in wastewater and surface waters poses a growing threat to aquatic ecosystems and public health. Their ability to interact with pharmaceutical compounds can lead to the formation of persistent complexes that increase the mobility and toxicity of contaminants. Microplastic particles act as a potential vector, adsorbing various substances, chemical compounds and pathogens on their surface [ 1 ]. Microplastics in the aquatic and wastewater environment originate from two main sources: primary and secondary. Primary microplastics are intentionally manufactured small plastic particles used in products like cosmetics, detergents, and pharmaceuticals, typically in the form of microbeads or capsules with defined sizes. In contrast, secondary microplastics are formed through the degradation of larger plastic waste (e.g., bags, bottles, films, synthetic fibers) due to physical, chemical, or biological processes (like UV radiation, abrasion, or microbial Molecules 2025,30, 3756 https://doi.org/10.3390/molecules30183756 Molecules 2025,30, 3756 2 of 20 activity), leading to particles that can interact with other pollutants, including pharmaceuticals. Microplastics ranging in size from 1 to 1000 µ m are classified as conventional microplastics (MPs), representing an intermediate category between nanoplastics (<1 µ m) and larger plastic debris (>1 mm). Scientific literature often distinguishes two subgroups within this range: 1–100 µ m, considered very fine particles capable of penetrating biological tissues, and 100–1000 µ m, which exhibit different sorption behaviors toward pollutants and are more easily detected under a microscope [2,3]. Plastics are characterized by exceptional durability, which under favorable environmental conditions may extend from hundreds to even thousands of years. Along with the dynamic increase in plastic waste, the scale of ecological threats is also intensifying. The widespread dispersal of microplastics is largely a consequence of human activity. Although the degradation of polymers may appear desirable from an environmental perspective, it does not automatically eliminate their harmfulness. Under the influence of atmospheric factors, microbial activity, and mechanical damage, plastic products gradually undergo structural and property changes, fragmenting into increasingly smaller particles. Contrary to expectations, this process is not beneficial, as microand nanoparticles readily spread throughout the environment, and, in parallel, various additives originally incorporated to impart specific properties to plastics are released during the breakdown of polymer networks. The presence of polyethylene microplastic particles in wastewater and surface waters has serious ecological and health consequences, especially in the context of the interaction of these particles with pharmaceuticals. There are a number of techniques and methods for detecting, identifying and quantifying microplastic particles [ 4 ]. The most commonly used methods include microscopic infrared spectroscopy (FTIR), Raman spectroscopy, and pyrolysis. Increasingly, multi-step strategies are being employed, combining initial visualization (optical microscopy) with subsequent spectroscopic analysis (micro-FTIR or Raman) and pyrolysis, which enhances both the quantitative and qualitative accuracy of microplastic identification [ 5 ]. Research is also being conducted on the impact of microplastic particles on living organisms such as earthworms [6]. Microplastics are an integral component of wastewater and should be taken into account when designing advanced, fourth-stage treatment systems. They constitute a contaminant in their own right, but also act as carriers for organic pollutants and microorganisms, including pathogens. One of the most promising methods for addressing such complex wastewater contamination is the application of cold plasma technology, which offers advanced capabilities for the degradation of persistent pollutants. This method is applied in food processing [ 7 ], surface cleaning [ 8 ], and sterilization [ 9 ], as well as in the removal of selected micropollutants from wastewater [ 10 ]. Using this technology allows for the controlled introduction of oxygen groups (C-O, C=O), roughening the surface, and lowering the molecular weight. This translates into susceptibility to further degradation and modifies sorption properties. Cold plasma, as a source of reactive oxygen and nitrogen species (ROS/RNS), demonstrates high application potential for surface modification of polymeric materials, including microplastics. Due to its low temperature and operation without the need for aggressive chemicals, this method is safe for the structure of the treated material while effectively inducing chemical changes such as increased polarity or the introduction of functional groups [ 11 ]. Applying cold plasma in studies on microplastics allows for a better understanding of how modified polyethylene surfaces affect their ability to sorb pollutants, including pharmaceutical compounds. The high controllability of the process and its environmentally friendly nature provide additional justification for choosing this technology in the context of the research problem. Despite growing research on the effects of cold plasma (CP) on microplastics and pharmaceuticals, several critical knowledge gaps remain. In particular, the long-term stability of plasma-modified mi- Molecules 2025,30, 3756 3 of 20 croplastics in environmental conditions is still poorly understood. The potential formation and toxicity of degradation byproducts resulting from CP treatment have not been fully assessed. Additionally, the scalability of CP processes for practical wastewater treatment applications remains largely unexplored. Addressing these gaps is essential to evaluate the environmental relevance and practical feasibility of plasma-based remediation strategies. The aim of the presented research was to evaluate the effectiveness of cold plasma treatment as a promising approach for the removal of pharmaceuticals and microplastics from wastewater. In particular, the research focused on the sorption behavior of selected pharmaceuticals on polyethylene particles and how this behavior was altered after lowtemperature plasma treatment. By addressing both degradation processes and adsorption phenomena, the study provides a relevant and timely contribution to understanding the potential of plasma-based technologies in mitigating emerging environmental contaminants. 2. Results As a result of the conducted studies, a dataset was obtained that enables the assessment of the effects of plasma treatment on the properties of polyethylene particles in different matrices. Both morphological features and changes in particle behavior as a function of cold plasma exposure time were analyzed. Based on basic observations under an optical microscope, both in water-based samples and treated wastewater, it was found that polyethylene particles do not stain with Nile Red. In the field of view, they appear as black, light-impermeable particles (Figure 1). This is most likely due to their high density as a reference material. Polyethylene (PE), especially high-molecular-weight, smooth, and crystalline forms, has low surface energy and a very limited capacity to sorb dyes. (a) (b) Figure 1. Polyethylene particles stained with Nile Red under UV light; observed against a red background using a red barrier filter, applied for the detection of red-range fluorescence and elimination of shorter-wavelength excitation light (a), and observed against a yellow background using a UV barrier filter (b). The polyethylene particles appear as spherical, black spheres opaque to light. 2.1. Microscopic Analysis of Polyethylene Particles in Water Through the analysis of water samples containing a polyethylene standard in a glass hemocytometer counting chamber, the number of PE particles per milliliter of sample was determined. Observations indicated that, after the longest exposure time of the sample to the plasma stream, the number of visible particles in the field of view increased (Figure 2). This was due to the formation of increasingly larger clusters, as the particles aggregated into progressively larger agglomerates. This tendency was also confirmed by SEM images (Figure 3). As a result of prolonged plasma treatment, individual microplastic particles began to cluster together, forming larger and more compact aggregates. This suggests that cold plasma may alter the surface properties of polyethylene, enhancing intermolecular interactions and potentially facilitating their removal from aquatic environments. Molecules 2025,30, 3756 4 of 20 0 10 20 30 40 50 60 70 PE.0 PE.2.5 PE.5 PE.7.5 PE.10 PE molecules/mL ×10,000 Smaple name Figure 2. Number of PE particles per 1 mL of sample based on hemocytometer chamber calculations in water samples with marked standard deviation. The observed increase in the number of objects after plasma treatment indicates fragmentation of larger PE particles into smaller agglomerates, which may indicate the effect of cold plasma on particle morphology; number of replications (N = 3). PE.0 PE.2.5 Figure 3. Cont. Molecules 2025,30, 3756 5 of 20 PE.5 PE.7.5 PE.10 Figure 3. Agglomerations of PE particles formed as a result of CP action over time observed under SEM. The progressive surface modification and clustering illustrate how plasma exposure alters particle morphology and promotes the formation of secondary microplastic structures relevant to environmental behavior. The application of cold plasma in a distilled water environment caused a noticeable change in the behavior of polyethylene standard particles. As shown in the SEM image (Figure 4), initially dispersed spherical PE particles began to form larger and more compact agglomerates following exposure to the plasma stream. This process intensified Molecules 2025,30, 3756 6 of 20 with increasing CP exposure time. The high-resolution SEM image reveals tightly packed spherical particles that underwent aggregation, showing a clear reduction in interparticle distances. This change indicates an increase in adhesion forces between particles. Furthermore, surface dulling and increased roughness were also observed, which may result from partial oxidation or the action of reactive plasma species (such as ROS or RNS), leading to modifications in the surface topography of PE. A probable mechanism behind agglomerate formation is the emergence of functional groups (e.g., hydroxyl, carbonyl) on the surface of PE particles, which increases their hydrophilicity and surface energy. As a result, intermolecular interactions such as van der Waals forces or potential hydrogen bonding are intensified, leading to their self-organization into larger structures. Figure 4. Scanning electron microscopy (SEM) visualization of PE particles aggregated into compact clusters following prolonged exposure to cold plasma in an aqueous environment. The formation of dense agglomerates indicates structural reorganization of the polymer surface, demonstrating how extended plasma treatment can drive secondary aggregation processes with potential implications for microplastic stability and transport in aquatic systems. The observed aggregation phenomenon may have significant environmental implications, particularly in the context of microplastic removal technologies. Larger and heavier agglomerates may be more easily separated using sedimentation, filtration, or flotation processes. As part of the morphological analysis, measurements of selected polyethylene particles were conducted using Fiji software (ImageJ 1.54p). During microscopic observations, fields of view with the smallest possible number of PE particles were selected to facilitate further image processing and accurate determination of particle sizes. The analysis showed that the diameter of individual particles prior to aggregation ranged from 10 to 45 µ m (Table 1). After CP treatment, no significant changes in the size of individual particles were observed, indicating that plasma exposure does not cause their shrinkage or elongation (Figure 5). These findings confirm that the effect of cold plasma is mainly focused on the surface modification of PE particles and their tendency to form larger structures through aggregation. Molecules 2025,30, 3756 7 of 20 Table 1. The dimensions of PE particles in individual samples were determined using the Fiji program (ImageJ 1.54p) in samples based on water. Sample Name Number of Objects in the Field of View Area [µm2] Width [µm] Height [µm] Perimeter [µm] PE.0 1 1004.782 35.958 35.316 121.199 2 547.951 26.326 26.326 88.535 3 450.235 25.042 24.400 80.765 PE.2.5 1 1005.440 35.714 35.714 112.200 PE.5 1 1022.069 36.989 35.713 120.375 2 682.464 31.887 29.336 100.186 PE.7.5 1 270.845 18.620 18,620 60.563 2 965.065 35.313 34.671 115.146 PE.10 1 768.723 31.250 31.250 102.958 2 685.749 28.699 29.974 97.173 PE.0 PE.2.5 PE.5 PE.7.5 PE.10 Figure 5. Visualization of the measured polyethylene molecules in a binary image in the Fiji program (ImageJ 1.54p) for quantitative analysis. This image processing step enables detection and measurement of particle clusters, providing the basis for assessing the impact of cold plasma treatment on particle number and size distribution. During the analysis of SEM images, the presence of PE particles with irregular, deformed shapes, deviating from the typical spherical morphology of the standard, was also observed. Such particles were visible in nearly every analyzed sample, regardless of the cold plasma exposure time. To ensure that these deformations were not caused by CP treatment, control observations were carried out on dry PE standard samples that had not undergone any plasma treatment. Irregularly shaped particles were also identified in these control samples, clearly indicating that cold plasma is not responsible for the degradation or structural breakdown of PE particles (Figure 6). This suggests that the observed deformations are likely of primary origin, resulting from manufacturing inconsistencies in the standard or prior physicochemical processes. The strongest peaks (observed in all tested samples) at wavenumbers 2918 cm −1 and 2849 cm −1 are attributed to the asymmetric and symmetric stretching vibrations of methylene groups (–CH 2 –) in polyethylene (PE) (Figure 7). Peaks observed at 1471 cm −1 and 1462 cm −1 correspond to bending vibrations of methylene groups. Additional characteristic polyethylene bands appear at 729 cm −1 and 719 cm −1 , which are assigned to the rocking vibrations of PE methylene groups [12]. In the case of samples exposed to plasma treatment and pharmaceuticals, the appearance of new bands in the range of 1700–1000 cm −1 and 600–500 cm −1 is observed [ 13 – 15 ]. This indicates the formation of new chemical bonds or the presence of adsorbed molecules, resulting from interfacial interactions between the polyethylene and the pharmaceutical compounds. Molecules 2025,30, 3756 8 of 20 Figure 6. Surface morphology of dry polyethylene (PE) standard without cold plasma (CP) treatment. The limited particle deformations observed here serve as a control reference, highlighting the baseline structural features of PE prior to plasma exposure and enabling comparison with the pronounced modifications induced by CP treatment. Figure 7. FTIR-ATR spectra of polyethylene (PE) particles before (PE.0) and after different durations of cold plasma treatment (PE.2.5, PE.5, PE.7.5, PE.10). All spectra show characteristic absorption bands of PE. After exposure to plasma, additional bands appear in the regions 1700 cm −1 and 1000–1200 cm−1, which can be assigned to oxygen-containing functional groups. Molecules 2025,30, 3756 9 of 20 2.2. Microscopic Analysis of Polyethylene Particles in Treated Wastewater Microscopic observations of samples containing treated wastewater with polyethylene in a hemocytometer counting chamber revealed an increasing trend in the number of particles observed within the field of view (Figure 8). This was associated with the formation of PE aggregates induced by cold plasma treatment. The number of visible particles increased with prolonged exposure of the sample to the CP stream. 0 10 20 30 40 50 60 70 PE.W.0 PE.W.2.5 PE.W.5 PE.W.7.5 PE.W.10 PE molecules/mL ×10,000 Sample name Figure 8. Number of PE particles per 1 mL of sample based on hemocytometer chamber calculations in treated wastewater with marked standard deviation. The observed increase in the number of objects after plasma treatment indicates fragmentation of larger PE particles into smaller agglomerates, which may indicate the effect of cold plasma on particle morphology; number of replications (N = 3). It should be emphasized that the particle counts presented in Figures 2and 8refer to clusters rather than individual polyethylene particles. The observed increase in the number of objects after plasma treatment most likely reflects fragmentation of larger pieces into smaller agglomerates, which are subsequently recognized as separate clusters. While this approach provides qualitative insight into fragmentation phenomena, it does not fully capture particle aggregation dynamics. Determination of size distribution parameters would allow for a more quantitative assessment, and such analyses are planned for future studies. As in the water-based samples, selected polyethylene particles were measured using Fiji software. During microscopic observations, fields of view containing the lowest possible number of PE particles were selected. The analysis showed that the diameter of individual particles prior to aggregation ranged from 10 to 45 µ m (Table 2). After CP treatment, as in the water-based samples, no significant changes in the size of individual particles were observed, indicating that plasma exposure does not alter the shape of the particles (Figure 9). This confirms that the effect of CP is mainly focused on surface modification of PE and influences the tendency of particles to form larger structures. All obtained results indicate that cold plasma does not cause degradation or deformation of polyethylene particles. Its effect is limited to surface modification, which leads to the intensification of aggregation processes. The observed phenomena suggest that CP may serve as an effective tool for supporting microplastic removal processes by increasing the tendency of particles to cluster into larger, more easily separable structures. Molecules 2025,30, 3756 16 of 20 fluorescence, with the aim of intercalating into the structure of PE particles during observation under an optical microscope. Samples after CP treatment were also observed using a Bürker Thoma chamber (Heinz Herenz Medizinalbedarf GmbH, Hamburg, Germany) with a volume of 0.0025 mm2. In order to identify the characteristic functional groups present in the chemical structure of the tested materials, Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) (SHIMADZU Irraffinity-1s, Kyoto, Japan) was used. The analysis of the FTIR spectrum provides information on vibrating molecules and their bonds with the immediate chemical environment. Spectral data were collected using a SHIMADZU spectrophotometer equipped with an ATR attachment featuring a diamond crystal. FTIRATR measurements were performed in the spectral range of 400 to 4000 cm −1 . A total of 60 scans per measurement were recorded, with a spectral resolution of 1 cm−1. For the studies related to the sorption of pharmaceuticals on PE particles, selected pharmaceuticals presented in Table 4were used. The analysis of pharmaceutical concentrations was performed using HPLC (High-Performance Liquid Chromatography). Chromatographic analysis was carried out using the Vanquish™ Analytical Purification LC system from Thermo Fisher Scientific (Waltham, MA, USA), equipped with an integrated Vanquish fraction collector. The chromatographic column used was an Accucore C18 column (150 mm ×3 mm) with a particle size of 2.6 µm. Table 4. Characteristics of the pharmaceutical substances used. Substance Therapeutic Group Specification Sulfamethoxazole (SMX) Antibiotic Crystalline powder, white or almost white. POL-AURA distributor (Zabrze, Poland) Trimethoprim (TMP) Antibiotic White to pale yellow powder. POL-AURA distributor (Zabrze, Poland) Diclofenac (DFC) Non-steroidal anti-inflammatory drugs Sodium salt, white powder. Sigma-Aldrich distributor (Saint Louis, MO, USA) Carbamazepine (CBZ) Anticonvulsant drug Powder with a color ranging from white to off-white. POL-AURA distributor (Zabrze, Poland) Caffeine (CAF) Other White powder. Biomus sp. z o.o. distributor (Lublin, Poland) 4.1. Water-Based Sample Preparation and Analysis To the sample containing distilled water with the PE standard, a drop of the surfactant Tween 20 (Sigma-Aldrich, Saint Louis, MO, USA) was added prior to plasma treatment. The samples were then exposed to cold plasma (CP) for time intervals ranging from 2.5 to 10 min. After plasma treatment, the samples were stained with Nile Red at a concentration of 0.3 mL of dye per 100 mL of sample. The sample staining procedure was performed based on modifications of the method proposed by Kang H. et al. [ 29 ]. Following staining, the samples were incubated in the dark for 30 min and subsequently observed under an optical microscope using red, yellow, or blue filters. Additionally, PE samples treated with CP in an aqueous matrix were examined under an SEM to observe potential structural changes in the particles. Samples containing distilled water with polyethylene particles are marked with the symbol—PE.time of contact of the sample with plasma, e.g., the control sample was marked: PE.0. Molecules 2025,30, 3756 17 of 20 4.2. Preparation and Analysis of Treated Wastewater Samples The subject of the study was treated wastewater originating from a municipal wastewater treatment plant, characterized by a total organic carbon (TOC) content of 10 mg/L. The corresponding chemical oxygen demand (COD) was approximately 25 mg O 2 /L, and the biochemical oxygen demand over five days (BOD 5 ) was 12 mg O 2 /L. The pH of the wastewater was measured at 7.24, indicating a slightly neutral environment. The electrical conductivity (EC) was 730 µ S/cm, which falls within the typical range for treated wastewater with a moderate content of dissolved mineral salts. ICPOES analysis resulted in the following characteristics: phosphorus (P) 2 mg/L, sodium (Na) 30 mg/L, potassium 21 mg/L, calcium 70 mg/L, magnesium 16 m/L. Samples of treated wastewater (50 mL) containing the PE standard were subjected to cold plasma (CP) treatment in the same manner as the distilled water samples. However, preparation for microscopic observation after Nile Red staining was preceded by digestion of organic matter in the samples. Digestion was performed using 30% hydrogen peroxide (perhydrol) (Biomus sp. z o.o., Lublin, Poland) in a 1:1 ratio. The samples were incubated with H 2 O 2 for 24 h at room temperature. The procedure for digesting organic matter in samples was performed based on information contained in the studies on the validation of microplastic sample preparation methods [ 30 ] and procedure optimization [ 31 ]. After digestion, the samples were centrifuged and rinsed three times with distilled water. They were then stained and observed under an optical microscope. Similarly, for samples containing treated sewage with polyethylene particles, the samples were marked with the symbol PE.W., corresponding to the time of contact of the sample with plasma, e.g., the control sample was marked: PE.W.0. 4.3. Preparation and Analysis of Polyethylene Samples Related to the Sorption of Pharmaceuticals on the Surface Pharmaceuticals were added to the treated wastewater samples containing PE (Table 1). Each pharmaceutical was added individually at a concentration of 20 mg/L. The samples were incubated for 24 h on a shaker (180 rpm) at room temperature. Subsequently, the samples were subjected to plasma treatment for 5 min. After plasma exposure, the samples were pressure-filtered to eliminate solid particles. Additionally, the resulting permeate was passed through a syringe filter (Sigma-Aldrich, Saint Louis, MO, USA). The samples were then subjected to chromatographic analysis, the conditions of which are described in the publication [ 10 ]. The efficiency of pharmaceutical concentration reduction expressed in % was determined based on Equation (1): E=100% −C×100% Cp (1) where E—efficiency of concentration reduction; Cp—initial pharmaceutical concentration; C—pharmaceutical concentration after the process. To evaluate the sorption capacity of untreated polyethylene (PE) microparticles for selected pharmaceutical compounds, each drug was tested at its nominal initial concentration. Based on the recorded equilibrium concentrations (Ce) after 24 h of contact, the amount of drug adsorbed per gram of PE (qe) was calculated using the mass balance Equation (2): qe=(Co −Ce)×V m(2) where Co—initial concentration (mg/L); Ce—equilibrium concentration (mg/L); V—volume of solution (L); m—mass of PE (g). Molecules 2025,30, 3756 18 of 20 4.4. Energy Balance Calculations: Assumptions and Equations An energy balance was prepared for the tested process using the Plasma TEC-X cold plasma generator (Table 5): Table 5. Assumptions and input data used to perform the energy analysis of the conducted research. Parameter Input Value Generator power 0.55 kW Plasma nozzle power 0.415 kW Air compressor 2 kW (at 4–8 bar, assuming continuous operation) Total system power (Pt) 2.965 kW Operating time 5 min (0.0833 h) Sample volume 50 mL (0.00005 m3) Electricity price (Ep)(industrial, scenarios): 0.15 EUR/kWh (base); Sensitivity: 0.10–0.25 EUR/kWh Initial pharmaceutical concentration 20 mg/L Contaminant reduction (%) (R) SMX 99.99%, TMP 98.11%, DFC 98.35%, CBZ 32.81% and CAF 0% The energy balance was performed based on the calculation of the input energy, defined as the product of the total system power (P t ) and treatment time. In the next step, the specific energy consumption (SEC) per 1% removal was calculated as the ratio of the input energy to the product of the sample volume and the percentage reduction in individual pharmaceuticals obtained after 5 min of cold plasma treatment. The estimation of energy costs was derived by multiplying the input energy by the average electricity price. Furthermore, the cost of achieving 1% reduction per 1 m 3 of treated water was determined as the product of SEC and the average electricity price. Author Contributions: Conceptualization, A.W.-P. and A.G.; methodology, A.W.-P. and B.K.; software, A.W.-P.; validation, A.W.-P., A.G. and B.K.; formal analysis, A.G., investigation, A.W.-P., B.K. and R.C.; resources, A.W.-P., A.G. and B.K.; data curation, A.W.-P., A.G., B.K. and R.C. writing—original draft preparation, A.W.-P. and A.G., writing—review and editing A.W.-P., A.G. and R.C.; visualization, A.W.-P., A.G., B.K. and R.C.; supervision, A.G.; project administration, A.W.-P. and A.G.; funding acquisition, A.W.-P. and A.G. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the National Science Centre, Poland, under the PRELUDIUM22 programme, grant number UMO-2023/49/N/ST8/02022; project title Evaluation of the Effect of Cold Plasma (CP) on the Removal Efficiency of Selected Organic Micropollutants from Wastewater. This research was funded by the statutory subvention of Czestochowa University of Technology, Faculty of Infrastructure and Environment. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Data is contained within the article. Conflicts of Interest: The authors declare no conflicts of interest. Abbreviations The following abbreviations are used in this manuscript: PE Polyethylene CP Cold Plasma SMX Sulfamethoxazole Molecules 2025,30, 3756 19 of 20 TMP Trimethoprim DFC Diclofenac CBZ Carbamazepine CAF Caffeine References 1. Dey, T.K.; Uddin, M.E.; Jamal, M. Detection and removal of microplastics in wastewater: Evolution and impact. 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