Dimitra A. Lambropoulou

Per- and polyfluoroalkyl substances (PFAS) represent a class of highly persistent synthetic chemicals widely recognized for their adverse effects on environmental and human health. In this study, a high-resolution mass spectrometry-based method for the determination of 20 PFAS in soils was developed and validated. The targeted PFAS comprise 20 of the 21 PFAS (PFAS-21) specified for soil monitoring under the EU Soil Monitoring Law (Directive (EU) 2025/2360). Sample extraction from the solid matrix was carried out through solid-liquid extraction (SLE) in three consecutive cycles with different solvents (methanol, acetonitrile, and a methanol solution with 0.1% ammonia), followed by a cleanup and preconcentration step using solid phase extraction (SPE). Analysis was performed by liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) using an Orbitrap mass analyzer. Method performance exhibited excellent linearity (R2 > 0.997), recoveries ranging from 70 to 114%, good precision (< 20%), and low limits of detection and quantification (up to 2.95 and 8.93 ng g-1, respectively). The method validated in this study offers a reliable and practical tool for the systematic surveillance of PFAS in soil, supporting the implementation of the EU Soil Monitoring Law, which requires Member States to include PFAS in their national monitoring programs for the first time, despite the current absence of harmonized concentration limits.

This study investigates the photocatalytic degradation of a mixture of three widely detected antidepressants, namely venlafaxine, bupropion, and sertraline, using a novel floating magnetic PET–Fe₃O₄/TiO₂ composite photocatalyst. Magnetic Fe₃O₄/TiO₂ nanoparticles were synthesized via co-precipitation/sol–gel and immobilized onto recycled poly(ethylene terephthalate) (PET) beads by non-solvent precipitation. The composites were characterized and evaluated for pharmaceutical removal under simulated solar irradiation, achieving high degradation efficiency and removing the antidepressants within 60–90 min depending on the compound. Performance was strongly influenced by inorganic loading, with the 50 wt% Fe₃O₄/TiO₂ composite giving the highest degradation rates. Water matrix composition also significantly affected degradation kinetics, with lower efficiencies observed in complex environmental matrices due to radical scavenging and competitive adsorption. Although the parent compounds degraded rapidly, complete mineralization required prolonged irradiation, indicating the formation of intermediate transformation products. Scale-up experiments in a continuous-flow pilot reactor showed performance comparable to laboratory-scale results, confirming applicability under realistic operating conditions. The composite beads retained their photocatalytic activity over the two reuse cycles investigated, although some deformation and TiO₂ loss were observed after reuse. Overall, the floating magnetic PET–Fe₃O₄/TiO₂ photocatalyst offers a sustainable and efficient approach for removing pharmaceutical contaminants from water, combining photocatalytic efficiency with facile recovery, reusability, and valorization of recycled PET waste.

Non-thermal plasma (NTP) has emerged as a promising, electrified technology for the degradation of pharmaceutical pollutants in wastewater. In this study, ambient air NTP was employed to degrade sulfadoxine (SDX), a sulfonamide antibiotic, using a pin-to-water dielectric barrier discharge (DBD). Plasma treatment alone achieved complete SDX degradation within 45 minutes, with only 33% mineralization after 90 minutes. To enhance performance, a hybrid plasma-assisted Fenton process was developed by introducing Fe2⁺ ions, enabling total SDX removal in just 20 minutes and achieving 33% mineralization in 30 minutes. The hybrid system also reduced nitrate (NO3⁻) accumulation by over 75% compared to plasma alone. Long-lived reactive species including H2O2, NO2⁻, and NO3⁻ were quantified over treatment time. High-resolution mass spectrometry (HRMS) identified six transformation products (TPs), four of which are reported for the first time contributing new mechanistic insight into plasma-based sulfonamide degradation pathways. These were primarily formed through desulfonation, aromatic bond cleavage, and hydroxylation pathways. In silico ecotoxicity screening using ECOSAR revealed that several TPs were as toxic or more toxic than the parent compound, particularly under chronic exposure to aquatic organisms. These results underline the effectiveness and relevance of plasma/Fenton processes for the treatment of sulfonamide-contaminated water, while also highlighting the need for ongoing assessment of TPs’ toxicity.

In this work, three functionalized hybrid composites, CS/PVA-VAN, CS/PVA-VAN@TiO₂ and CS/GO/PVA-VAN@TiO₂, were synthesized and applied for adsorption evaluation on two common non-steroidal anti-inflammatory drugs, i.e., diclofenac (DCF) and ketoprofen (KTP). The structural and morphological characteristics of new composites were identified via Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET techniques. BET analysis demonstrated that the CS/GO/PVA-Van@TiO₂ composite has a surface area 64.86 m²/g, which is twice that of CS/PVA-Van. Moreover, adsorption evaluation was achieved at an optimum pH condition (pH 5.0) for both drugs. In addition, the kinetic data fitted better in a pseudo-second-order kinetic model, while the adsorption was heterogeneous and multilayer. The adsorption capacity of CS/GO/PVA-VAN@TiO₂ was found to be 114.53 mg/g and 65.20 mg/g for diclofenac and ketoprofen, respectively. Thermodynamic analysis confirmed that the adsorption process was endothermic and spontaneous for all pollutants. Moreover, the kinetic swelling and stability studies demonstrated that graphene oxide contributed to improving the structural compactness and stability of composite. Finally, the adsorption performance of the optimal composite material was investigated in a binary system of non-steroidal anti-inflammatory drugs in various ratios.

Microplastics (MPs) and nanoplastics (NPs) have emerged as pervasive pollutants across different aquatic systems on a global basis, yet integrated assessments linking wastewater, riverine, and marine environments remain scarce. The present study provides the first comprehensive evaluation of MPs in three interconnected aquatic matrices of Northern Greece, namely surface seawater from the Thermaic Gulf, surface freshwater from the Axios River, and influent and effluent wastewaters from the Thessaloniki WWTP (Sindos). During two sampling periods spanning late 2023 and spring 2024, suspected MPs were isolated, morphologically classified by stereomicroscopy, and chemically characterized through pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). MPs were ubiquitously detected in all substrates, exhibiting distinct spatial and compositional patterns. Seawater samples displayed moderate concentrations (1.5–4.8 items m⁻³) dominated by fibers and fragments, while riverine samples contained slightly higher levels (0.5–2.5 items m⁻³), enriched in fibrous forms and polyolefins (PE, PP). Wastewater influents showed the highest MP abundance (78–200 items L⁻¹; 155.6–392.3 µg L⁻¹), decreasing significantly in effluents (11–44 items L⁻¹; 27.8–74.3 µg L⁻¹), corresponding to a removal efficiency of 81–87.5%, being the first indicative removal efficiencies in a Greek WWTP. Among the different polymers detected, polyethylene, polypropylene, and poly(ethylene terephthalate) were identified as the most prevalent polymers across all matrices. Interestingly, a shift toward smaller size classes (125–500 µm) in effluents indicated in-plant fragmentation processes, while increased concentrations during December coincided with increased rainfall, highlighting the influence of hydrological conditions on MP fluxes. The combined morphological and polymer-specific approach provides a holistic zunderstanding of MP transport from inland to marine systems, establishing essential baseline data for Mediterranean environments and reinforcing the need for integrated monitoring and mitigation strategies.

This study investigates amorphous anodized porous TiO₂ (a-TiO₂) as a substrate for iridium-based oxygen evolution catalysts. The substrates were prepared via anodization of Ti foil in a glycerol-based solution for 15 min @ 60 V. Nickel was subsequently electrodeposited to act both as a conductive and sacrificial layer for the galvanic deposition of iridium from an Ir(IV) chloro-complex solution. Electrochemical anodization resulted in a uniform IrO_x layer on the a-TiO₂ substrate, featuring Ir aggregates ~250 nm in size and an Ir:Ni atomic ratio of ca. 7, as determined by EDS analysis. The quantity of Ni determined by ICP-MS bulk analysis indicated that Ni resided also within the porous matrix. Varying the Ni deposition charge density (q_Ni) revealed that an intermediate loading (1463 mC cm⁻²) provided the best balance between Ir accessibility during the galvanic replacement step and electronic continuity. The optimized IrO_x/Ir-Ni/a-TiO₂ electrode achieved excellent OER performance (η = 344 mV @ 10 mA cm⁻²; 1.68 mA μg_Ir⁻¹ @ η = 300 mV) at an ultra-low Ir loading of 2.15 μg_Ir cm⁻² and demonstrated good short-term stability, with only a 20 mV potential increase over 4 h of continuous operation at 5.5 mA cm⁻². Overall, this strategy offers a scalable pathway for producing efficient OER electrodes with minimal noble metal loading.