Machine Learning in Membrane Design: From Property Prediction to AI-Guided Optimization.

Porous membranes, either polymeric or two-dimensional materials, have been extensively studied because of their outstanding performance in many applications such as water filtration. Recently, inspired by the significant success of machine learning (ML) in many areas of scientific discovery, researchers have started to tackle the problem in the field of membrane design using data-driven ML tools. In this Mini Review, we summarize research efforts on three types of applications of machine learning in membrane design, including (1) membrane property prediction using ML, (2) gaining physical insight and drawing quantitative relationships between membrane properties and performance using explainable artificial intelligence, and (3) ML-guided design, optimization, or virtual screening of membranes. On top of the review of previous research, we discuss the challenges associated with applying ML for membrane design and potential future directions.

Development of Biocompatible Electrospun PHBV-PLLA Polymeric Bilayer Composite Membranes for Skin Tissue Engineering Applications.

Bilayer electrospun fibers aimed to be used for skin tissue engineering applications were fabricated for enhanced cell attachment and proliferation. Different ratios of PHBV-PLLA (70:30, 80:20, and 90:10 w/w) blends were electrospun on previously formed electrospun PHBV membranes to produce their bilayers. The fabricated electrospun membranes were characterized with FTIR, which conformed to the characteristic peaks assigned for both PHBV and PLLA. The surface morphology was evaluated using SEM analysis that showed random fibers with porous morphology. The fiber diameter and pore size were measured in the range of 0.7 ± 0.1 µm and 1.9 ± 0.2 µm, respectively. The tensile properties of the bilayers were determined using an electrodynamic testing system. Bilayers had higher elongation at break (44.45%) compared to the monolayers (28.41%) and improved ultimate tensile strength (7.940 MPa) compared to the PHBV monolayer (2.450 MPa). In vitro cytotoxicity of each of the scaffolds was determined via culturing MC3T3 (pre-osteoblastic cell line) on the membranes. Proliferation was evaluated using the Alamar Blue assay on days 3, 7, and 14, respectively. SEM images of cells cultured on membranes were taken in addition to bright field imaging to visually show cell attachment. Fluorescent nuclear staining performed with DAPI was imaged with an inverted fluorescent microscope. The fabricated bilayer shows high mechanical strength as well as biocompatibility with good cell proliferation and cell attachment, showing potential for skin substitute applications.

Synthesis of low-density polyethylene derived carbon nanotubes for activation of persulfate and degradation of water organic micropollutants in continuous mode.

Plastic derived carbon nanotubes (CNTs) were tested as catalysts in persulfate activation for the first time. Four catalysts were prepared by wetness impregnation and co-precipitation (using Al2O3, Ni, Fe and/or Al) and implemented to grow CNTs by chemical vapour deposition (CVD) using low-density polyethylene (LDPE) as carbon feedstock. A catalyst screening was performed in batch mode and the best performing CNTs (CNT@Ni+Fe/Al2O3-cp) led to a high venlafaxine mass removal rate (3.17 mg g-1 h-1) in ultrapure water after 90 min (even with a mixture of micropollutants). Its degradation increased when the matrix was replaced by drinking water and negligibly affected in surface water. A composite polymeric membrane was then fabricated with CNT@Ni+Fe/Al2O3-cp and polyvinylidene fluoride (PVDF), a high venlafaxine mass removal rate in surface water being also observed in 24 h of continuous operation. Therefore, the results herein reported open a window of opportunity for the valorisation of plastic wastes in this catalytic application performed in continuous mode.

Development of a Polymeric Membrane Impregnated with Poly-Lactic Acid (PLA) Nanoparticles Loaded with Red Propolis (RP).

The main objectives of this study were to develop and characterize hydrophilic polymeric membranes impregnated with poly-lactic acid (PLA) nanoparticles (NPs) combined with red propolis (RP). Ultrasonic-assisted extraction was used to obtain 30% (w/v) red propolis hydroalcoholic extract (RPE). The NPs (75,000 g mol-1) alone and incorporated with RP (NPRP) were obtained using the solvent emulsification and diffusion technique. Biopolymeric hydrogel membranes (MNPRP) were obtained using carboxymethylcellulose (CMC) and NPRP. Their characterization was performed using thermal analysis, Fourier transform infrared (FTIR), total phenols (TPC) and flavonoids contents (TFC), and antioxidant activity through the radical scavenging assay with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and Ferric reducing antioxidant power (FRAP). The identification and quantification of significant RP markers were performed through UPLC-DAD. The NPs were evaluated for particle size, polydispersity index, and zeta potential. The TPC for RPE, NPRP, and MNPRP was 240.3 ± 3.4, 191.7 ± 0.3, and 183.4 ± 2.1 mg EGA g-1, while for TFC, the value was 37.8 ± 0.9, 35 ± 3.9, and 26.8 ± 1.9 mg EQ g-1, respectively. Relevant antioxidant activity was also observed by FRAP, with 1400.2 (RPE), 1294.2 (NPRP), and 696.2 µmol Fe2+ g-1 (MNPRP). The primary markers of RP were liquiritigenin, isoliquiritigenin, and formononetin. The particle sizes were 194.1 (NPs) and 361.2 nm (NPRP), with an encapsulation efficiency of 85.4%. Thermal analysis revealed high thermal stability for the PLA, nanoparticles, and membranes. The DSC revealed no interaction between the components. FTIR allowed for characterizing the RPE encapsulation in NPRP and CMC for the MNPRP. The membrane loaded with NPRP, fully characterized, has antioxidant capacity and may have application in the treatment of skin wounds.

Synthesis of Graphene-Based Nanocomposites for Environmental Remediation Applications: A Review.

The term graphene was coined using the prefix "graph" taken from graphite and the suffix "-ene" for the C=C bond, by Boehm et al. in 1986. The synthesis of graphene can be done using various methods. The synthesized graphene was further oxidized to graphene oxide (GO) using different methods, to enhance its multitude of applications. Graphene oxide (GO) is the oxidized analogy of graphene, familiar as the only intermediate or precursor for obtaining the latter at a large scale. Graphene oxide has recently obtained enormous popularity in the energy, environment, sensor, and biomedical fields and has been handsomely exploited for water purification membranes. GO is a unique class of mechanically robust, ultrathin, high flux, high-selectivity, and fouling-resistant separation membranes that provide opportunities to advance water desalination technologies. The facile synthesis of GO membranes opens the doors for ideal next-generation membranes as cost-effective and sustainable alternative to long existing thin-film composite membranes for water purification applications. Many types of GO-metal oxide nanocomposites have been used to eradicate the problem of metal ions, halomethanes, other organic pollutants, and different colors from water bodies, making water fit for further use. Furthermore, to enhance the applications of GO/metal oxide nanocomposites, they were deposited on polymeric membranes for water purification due to their relatively low-cost, clear pore-forming mechanism and higher flexibility compared to inorganic membranes. Along with other applications, using these nanocomposites in the preparation of membranes not only resulted in excellent fouling resistance but also could be a possible solution to overcome the trade-off between water permeability and solute selectivity. Hence, a GO/metal oxide nanocomposite could improve overall performance, including antibacterial properties, strength, roughness, pore size, and the surface hydrophilicity of the membrane. In this review, we highlight the structure and synthesis of graphene, as well as graphene oxide, and its decoration with a polymeric membrane for further applications.

The Long-Lasting Story of One Sensor Development: From Novel Ionophore Design toward the Sensor Selectivity Modeling and Lifetime Improvement.

The metalloporphyrin ligand bearing incorporated anion-exchanger fragment, 5-[4-(3-trimethylammonium)propyloxyphenyl]-10,15,20-triphenylporphyrinate of Co(II) chloride, CoTPP-N, has been tested as anion-selective ionophore in PVC-based solvent polymeric membrane sensors. A plausible sensor working mechanism includes the axial coordination of the target anion on ionophore metal center followed by the formed complex aggregation with the second ionophore molecule through positively charged anion-exchanger fragment. The UV-visible spectroscopic studies in solution have revealed that the analyte concentration increase induces the J-type porphyrin aggregation. Polymeric membranes doped with CoTPP-N showed close to the theoretical Nernstian response toward nitrite ion, preferably coordinated by the ionophore, and were dependent on the presence of additional membrane-active components (lipophilic ionic sites and ionophore) in the membrane phase. The resulting selectivity was a subject of specific interaction and/or steric factors. Moreover, it was demonstrated theoretically and confirmed experimentally that the selection of a proper ratio of ionophore and anionic additive can optimize the sensor selectivity and lifetime.

Removal of sulfadiazine from simulated industrial wastewater by a membrane bioreactor and ozonation.

Ozonation can be used as a polishing treatment for degrading low-concentration pharmaceutical compounds recalcitrant to biological treatment, when large amounts of biodegradable organics have been previously removed by biological processes. Nevertheless, a systematic investigation has not yet been carried out for the coupled MBR + O3 process through an experimental design approach. Thereby, the purpose of this study is to evaluate the performance of different processes (membrane bioreactor-MBR, ozonation; and integrated MBR + O3) for removing the antibiotic sulfadiazine (SDZ) from a synthetic wastewater matrix of industrial interest. The MBR behavior was monitored over seven months for different parameters (pH, temperature, permeate flow, transmembrane pressure, biological oxygen demand-BOD5, chemical oxygen demand-COD, total organic carbon-TOC, solids, and SDZ concentration). Additionally, the amount of SDZ sorbed onto the sludge was characterized, an issue which is scarcely addressed in most research works. Ozonation experiments were conducted in batch mode in a 2-L glass reactor provided with openings for gas flow. For the MBR + O3 process, the effects of gas flow rate (0.1-1.5 L min-1) and inlet ozone concentration (4-12 mg L-1) on SDZ removal from the MBR permeate were systematically assessed using a Doehlert experimental design and response surface methodology. The results indicated that the MBR system showed good performance regarding organic matter removal efficiency, evaluated in terms of BOD5 (91.5%), COD (93.1%) and TOC (96.3%). In contrast, SDZ was partially removed (33%) by the MBR; in that case, the results indicated that the antibiotic was moderately removed with the sludge and partially biodegraded. In turn, the MBR + O3 system showed excellent performance for removing SDZ (100%), TOC (97%), BOD5 (94%) and COD (97%). The statistical analysis confirmed that the influence of ozone gas flow rate upon the SDZ removal rate was more important than that exhibited by inlet ozone concentration. Therefore, coupling MBR and ozone can be considered a promising alternative for point source treatment of antibiotic production wastewater.

Special Issue: "New Trends in Membrane Preparation and Applications".

This Special Issue aims to provide a collection of recent advancements in the field of membrane science [...].

Preparation and Characterization of TiO2-PVDF/PMMA Blend Membranes Using an Alternative Non-Toxic Solvent for UF/MF and Photocatalytic Application.

The approach of the present work is based on the use of poly (methylmethacrylate) (PMMA) polymer, which is compatible with PVDF and TiO2 nanoparticles in casting solutions, for the preparation of nano-composites membranes using a safer and more compatible solvent. TiO2 embedded poly (vinylidene fluoride) (PVDF)/PMMA photocatalytic membranes were prepared by phase inversion method. A non-solvent induced phase separation (NIPS) coupled with vapor induced phase separation (VIPS) was used to fabricate flat-sheet membranes using a dope solution consisting of PMMA, PVDF, TiO2, and triethyl phosphate (TEP) as an alternative non-toxic solvent. Membrane morphology was examined by scanning electron microscopy (SEM). Backscatter electron detector (BSD) mapping was used to monitor the inter-dispersion of TiO2 in the membrane surface and matrix. The effects of polymer concentration, evaporation time, additives and catalyst amount on the membrane morphology and properties were investigated. Tests on photocatalytic degradation of methylene blue (MB) were also carried out using the membranes entrapped with different concentrations of TiO2. The results of this study showed that nearly 99% MB removal can be easily achieved by photocatalysis using TiO2 immobilized on the membrane matrix. Moreover, it was observed that the quantity of TiO2 plays a significant role in the dye removal.

A review of polymeric membranes and processes for potable water reuse.

Conventional water resources in many regions are insufficient to meet the water needs of growing populations, thus reuse is gaining acceptance as a method of water supply augmentation. Recent advancements in membrane technology have allowed for the reclamation of municipal wastewater for the production of drinking water, i.e., potable reuse. Although public perception can be a challenge, potable reuse is often the least energy-intensive method of providing additional drinking water to water stressed regions. A variety of membranes have been developed that can remove water contaminants ranging from particles and pathogens to dissolved organic compounds and salts. Typically, potable reuse treatment plants use polymeric membranes for microfiltration or ultrafiltration in conjunction with reverse osmosis and, in some cases, nanofiltration. Membrane properties, including pore size, wettability, surface charge, roughness, thermal resistance, chemical stability, permeability, thickness and mechanical strength, vary between membranes and applications. Advancements in membrane technology including new membrane materials, coatings, and manufacturing methods, as well as emerging membrane processes such as membrane bioreactors, electrodialysis, and forward osmosis have been developed to improve selectivity, energy consumption, fouling resistance, and/or capital cost. The purpose of this review is to provide a comprehensive summary of the role of polymeric membranes in the treatment of wastewater to potable water quality and highlight recent advancements in separation processes. Beyond membranes themselves, this review covers the background and history of potable reuse, and commonly used potable reuse process chains, pretreatment steps, and advanced oxidation processes. Key trends in membrane technology include novel configurations, materials and fouling prevention techniques. Challenges still facing membrane-based potable reuse applications, including chemical and biological contaminant removal, membrane fouling, and public perception, are highlighted as areas in need of further research and development.

Instantaneous Click Chemistry by a Copper-Containing Polymeric-Membrane-Installed Microflow Catalytic Reactor.

The copper(I)-catalyzed Huisgen cycloaddition (azide-alkyne cycloaddition) is an important reaction in click chemistry that ideally proceeds instantaneously. An instantaneous Huisgen cycloaddition has been developed that uses a novel catalytic dinuclear copper complex-containing polymeric membrane-installed microflow device. A polymeric membranous copper catalyst was prepared from poly(4-vinylpyridine), copper(II) sulfate, sodium chloride, and sodium ascorbate at the interface of two laminar flows inside microchannels. Elucidation of the structure by XANES, EXAFS, and elemental analysis, as well as second-order Møller-Plesset perturbation theory (MP2) calculations and density functional theory (DFT) calculations assigned the local structure near Cu as a µ-chloro dinuclear Cu(I) complex. The microflow device promotes the instantaneous click reaction of a variety of alkynes and organic azides to afford the corresponding triazoles in quantitative yield.

Experimental evidence of rapid water transport through carbon nanotubes embedded in polymeric desalination membranes.

As water molecules permeate ultrafast through carbon nanotubes (CNTs), many studies have prepared CNTs-based membranes for water purification as well as desalination, particularly focusing on high flux membranes. Among them, vertically aligned CNTs membranes with ultrahigh water flux have been successfully demonstrated for fundamental studies, but they lack scalability for bulk production and sufficiently high salt rejection. CNTs embedded in polymeric desalination membranes, i.e., polyamide thin-film composite (TFC) membranes, can improve water flux without any loss of salt rejection. This improved flux is achieved by enhancing the dispersion properties of CNTs in diamine aqueous solution and also by using cap-opened CNTs. Hydrophilic CNTs were prepared by wrapping CNT walls via bio-inspired surface modification using dopamine solution. Cap-opening of pristine CNTs is performed by using a thermo-oxidative process. As a result, hydrophilic, cap-opened CNTs-embedded polyamide TFC membranes are successfully prepared, which show much higher water flux than pristine polyamide TFC membrane. On the other hand, less-disperse, less cap-opened CNTs-embedded TFC membranes do not show any flux improvement and rather lead to lower salt rejection properties.

Fabrication of CMC/PVA/Dextrin-Based Polymeric Membrane for Controlled Release of Cefixime With Enhanced Antibacterial Activity.

This study focuses on the investigation of the significance of polymers in drug delivery approaches. The carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA) and dextrin-based hydrogel membrane were prepared and employed for the sustained release of third-generation oral antibiotic (cefixime). Different proportions of CMC, PVA and dextrin were blended and hydrogel membranes were fabricated via solvent casting method. The prepared membrane was characterized by FTIR, SEM, UV-visible, TGA and swelling analysis. Cefixime drug was incorporated in the CMC/PVA/dextrin matrix and drug release was investigated. The sustained release of the tested drug (cefixime) was investigated and the drug was released in 120 min in the phosphate-buffered saline (PBS) solution. The antibacterial activity of the prepared membrane was promising against Proteus vulgaris, salmonella typhi, Escherichia coli and Bacillus subtilis strains. The swelling capabilities, thermal stability and non-toxic nature of the prepared CMC/PVA/dextrin membrane could have potential applications for cefixime drug in delivery in a controlled way for the treatment of infectious diseases.

Biogas Upgrading Using a Single-Membrane System: A Review.

In recent years, the use of biogas as a natural gas substitute has gained great attention. Typically, in addition to methane (CH4), biogas contains carbon dioxide (CO2), as well as small amounts of impurities, e.g., hydrogen sulfide (H2S), nitrogen (N2), oxygen (O2) and volatile organic compounds (VOCs). One of the latest trends in biogas purification is the application of membrane processes. However, literature reports are ambiguous regarding the specific requirement for biogas pretreatment prior to its upgrading using membranes. Therefore, the main aim of the present study was to comprehensively examine and discuss the most recent achievements in the use of single-membrane separation units for biogas upgrading. Performing a literature review allowed to indicate that, in recent years, considerable progress has been made on the use of polymeric membranes for this purpose. For instance, it has been documented that the application of thin-film composite (TFC) membranes with a swollen polyamide (PA) layer ensures the successful upgrading of raw biogas and eliminates the need for its pretreatment. The importance of the performed literature review is the inference drawn that biogas enrichment performed in a single step allows to obtain upgraded biogas that could be employed for household uses. Nevertheless, this solution may not be sufficient for obtaining high-purity gas at high recovery efficiency. Hence, in order to obtain biogas that could be used for applications designed for natural gas, a membrane cascade may be required. Moreover, it has been documented that a significant number of experimental studies have been focused on the upgrading of synthetic biogas; meanwhile, the data on the raw biogas are very limited. In addition, it has been noted that, although ceramic membranes demonstrate several advantages, experimental studies on their applications in single-membrane systems have been neglected. Summarizing the literature data, it can be concluded that, in order to thoroughly evaluate the presented issue, the long-term experimental studies on the upgrading of raw biogas with the use of polymeric and ceramic membranes in pilot-scale systems are required. The presented literature review has practical implications as it would be beneficial in supporting the development of membrane processes used for biogas upgrading.

Piezoelectric and Dielectric Electrospun Fluoropolymer Membranes for Oral Mucosa Regeneration: A Comparative Study.

Wound healing of the oral mucosa is an urgent problem in modern dental surgical practice. This research article presents and compares the findings of the investigations of the structural, physicochemical, and biological characteristics of two types of polymeric membranes used for the regeneration of oral mucosa. The membranes were prepared from poly(tetrafluoroethylene) (PTFE) and a copolymer of vinylidene fluoride and tetrafluoroethylene (VDF-TeFE) and analyzed via scanning electron microscopy, atomic force microscopy, X-ray diffraction analysis, and Fourier transform infrared spectroscopy. Investigation results obtained indicate that both types of membranes are composed of thin fibers: (0.57 ± 0.25) µm for PTFE membranes and (0.43 ± 0.14) µm for VDF-TeFE membranes. Moreover, the fibers of VDF-TeFE membranes exhibit distinct piezoelectric properties, which are confirmed by piezoresponse force microscopy and X-ray diffraction. Both types of membranes are hydrophobic: (139.7 ± 2.5)° for PTFE membranes and (133.5 ± 2.0)° for VDF-TeFE membranes. In vitro assays verify that both membrane types did not affect the growth and division of mice fibroblasts of the 3T3-L1 cell line, with a cell viability in the range of 88-101%. Finally, in vivo comparative experiments carried out using Wistar rats demonstrate that the piezoelectric VDF-TeFE membranes have a high ability to regenerate oral mucosa.

Highly Stretchable Thermoplastic Polyurethane Separators for Li-Ion Batteries Based on Non-Solvent-Induced Phase Separation Method.

The growing interest in wearable and portable devices has stimulated the need for flexible and stretchable lithium-ion batteries (LiBs). A crucial component in these batteries is the separator, which provides a pathway for Li-ion transfer and prevents electrode contact. In a flexible and stretchable LiB, the separator must exhibit stretchability and elasticity akin to its existing counterparts. Here, we developed a non-modified thermoplastic polyurethane (TPU) separator using the non-solvent induced phase separation (NIPS) technique. We compared their performance with commercially available polypropylene (PP) separators. Our results demonstrate that TPU separators exhibit superior elasticity based on repeated stretch/release tests with excellent thermal stability and electrolyte wettability. Furthermore, our findings confirm that TPU separators, even after being repeatedly stretched and released, can function effectively without severe damage in a fabricated coin cell LiB with high oxidative stability, as evidenced by linear sweep voltammetry, like commercially available separators.

Ion transfer mediated by TEMPO in ionophore-doped thin films for multi-ion sensing by cyclic voltammetry.

We report here on the development of thin-layer ion-selective membranes containing lipophilic TEMPO as a phase-transfer redox mediator for the simultaneous detection of non-redoxactive ions. This redox probe was recently introduced by our group and provides ideal ion-transfer waves when the membrane is interrogated by cyclic voltammetry. To perform multianalyte detection in the same sensing film, plasticized PVC-based membranes were doped with lithium and potassium ionophores in addition to a lipophilic cation-exchanger. The ionophores allow for ion discrimination owing to the different ionophore-cation complexation constants and the oxidation of TEMPO to the oxoammonium form results in the selective transfer of lithium and potassium at different potentials. The resulting voltammograms have half-peak widths of 100 and 102 mV, and the peak separation between anodic and cathodic scans is 8 and 9 mV for lithium and potassium, respectively, close to theoretical expectations. High peak resolution was observed, and the ion-transfer waves are still distinguishable when the ion activities differ by three orders of magnitude. These parameters are remarkably better than those obtained with other redox probes, which is important for multianalyte detection in the same voltammetric scan. Optimized membranes showed independent Nernstian shifts (slopes of 59.23 mV and 54.8 mV for K+ and Li+, respectively) of the peak position for increasing ion concentrations. An idealized model for two ionophore-based membranes combining redox and phase-boundary potentials was applied to the proposed system with excellent correlation. Potassium and lithium ions were simultaneously detected in undiluted human serum samples with good accuracy and precision.

Sexual hormones monitoring in surface waters and wastewaters from Northern Italy by thin film microextraction coupled with HPLC-MS/MS.

The occurrence of sex steroid hormones, viz. oestrogens and progestins, in aquatic ecosystems is of global concern due to their role as endocrine disrupting chemicals, even at low concentration (µg L-1 or less). Thus, it is essential to monitor these organic pollutants to get a realistic picture of their presence and to control their contamination levels in environmental water bodies. In this respect, we have explored the use of self-prepared polymeric films as novel sorptive phase for the microextraction of 17ß-estradiol, 17α-ethinylestradiol, estrone, progesterone, medroxyprogesterone acetate and hydroxyprogesterone. The thin film microextraction procedure has been developed, evaluating different film compositions, sample volumes and elution conditions to recover the sorbed analytes. The overall method provides good reproducibility (RSD < 12%) and recoveries higher than 60%. The final method has been applied to environmental monitoring in surface waters (river and lake samples) and urban wastewater treatment plant effluents and influents from Northern Italy, to get a contamination snapshot of this highly urbanized area.

Carbon Dioxide Capture by Emerging Innovative Polymers: Status and Perspectives.

A significant amount of research has been conducted in carbon dioxide (CO2) capture, particularly over the past decade, and continues to evolve. This review presents the most recent advancements in synthetic methodologies and CO2 capture capabilities of diverse polymer-based substances, which includes the amine-based polymers, porous organic polymers, and polymeric membranes, covering publications in the last 5 years (2019-2024). It aims to assist researchers with new insights and approaches to develop innovative polymer-based materials with improved capturing CO2 capacity, efficiency, sustainability, and cost-effective, thereby addressing the current obstacles in carbon capture and storage to sooner meeting the net-zero CO2 emission target.

Biochar-based polymeric film as sustainable and efficient sorptive phase for preconcentration of steroid hormones in environmental waters and wastewaters.

BACKGROUND: The environmental impact of sample preparation should be minimized through simplification of the procedures and the use of natural, renewable and/or reusable materials. In such scenario, thin-film microextraction fulfils the former criteria, as it enables few steps and miniaturization, thus small amount of extraction phase. At the same time, the use of sorbents such as biochars obtained from biomass waste is even more promoted due to their availability at low cost and increased life-cycle in a circular economy vision. However, it is not always easy to combine these criteria in sample preparation. RESULTS: A thin film microextraction was developed for the determination of steroids in aqueous samples, entailing a membrane made of cellulose triacetate and a wood-derived biochar (Nuchar®) as carbon precursor. Different characterization techniques showed the successful preparation, whereas the sorption kinetics experiments demonstrated that biochar is responsible for the extraction with the polymer acting as a smart support. After a study about membranes' composition in terms of biochar amounts (4 %, 10 %, 16 % wt) and type of synthesis set up, the ceramic 3D-mold was selected, achieving reproducible and ready-to-use membranes with composition fixed as 10 %. Different elution conditions, viz. type and time of agitation, type, composition and volume of eluent, were evaluated. The final microextraction followed by HPLC-MS/MS quantification was successfully validated in river and wastewater treatment plant effluent samples in terms of accuracy (R% 64-123 %, RSD<19 % in river; R% 61-118 %, RSD <18 % in effluent, n = 4), sensitivity (MQLs 0.2-8.5 ng L-1) and robustness. SIGNIFICANCE: This novel biochar-based polymeric film proved to be a valid and sustainable sorbent, in terms of extraction capability, ease of preparation and greenness. By comparison with literature and the greenness evaluation with the most recent metric tools, this method expands the potential applicability of the thin-film microextraction and opens up innovative scenarios for sustainable procedures entailing the use of biochars entrapped in bio-polymers.