Search Results (260)

Composite aerogels based on polytetrafluoroethylene (PTFE) and graphene oxide (GO) with a high polymer content of 90, 95 and 98 wt.% were synthesized for the first time. It was found that GO performs a structure-forming function, allowing the production of monolithic three-dimensional frameworks stable under freeze-drying conditions even at a minimal concentration of 2 wt.%, whereas pure PTFE is destroyed under these conditions. Subsequent annealing of the composites at 370 °C, which is higher than the decomposition temperature of oxygen-containing groups of GO and the melting point of PTFE, leads to the formation of PTFE/reduced graphene oxide (rGO) aerogels. A direct dependence of shrinkage during annealing on the polymer content was observed: it sharply increases from 2.1% to 26.6% with an increasing proportion of PTFE. This effect is explained by the dominant role of capillary forces pulling together the rGO sheets in the molten polymer, while the rGO frame resists the shrinkage. The most significant result is the achievement of a record low water sorption capacity (Q_w) for an aerogel with 98% PTFE, amounting to only 0.001 g/g. This value is several orders of magnitude lower than that of pure rGO aerogel (~20 g/g), confirming that a high content of hydrophobic polymer combined with thermal treatment effectively shields the hydrophilic sites on the surface of the rGO sheets. The composites obtained in this work exhibit high hydrophobicity (contact angles up to 144°) and unique potential for the selective absorption of organic solvents from water. Full article

The compositional complexity of plant-derived food matrices and the structural diversity of phenolic compounds influence sample preparation, promoting miniaturized solid-phase extraction using advanced sorbents for their determination. This critical systematic review examines these sorbents over the 2016–2025 period, organizing the analysis according to their structural platform to investigate how their architecture is associated with the reported interaction mechanisms, to interpret analytical performance in the appropriate context, and to identify methodological trends, limitations, and knowledge gaps. Through a systematic search in Scopus and the application of predefined eligibility criteria, 37 studies were selected and included in the critical narrative synthesis. The analysis primarily covered molecularly imprinted sorbents, functionalized polymeric and carbon-based platforms, and layered inorganic materials. Magnetic separation using Fe₃O₄ emerged as the most widely employed operational strategy across the analyzed platforms, while flavonoids and phenolic acids were the predominant target subclasses. Identified gaps include the infrequent evaluation of matrix effects, the limited formal assessment of method sustainability, and the scarce experimental validation of the relative contribution of retention mechanisms in systems involving multiple simultaneous interactions. By organizing the available evidence according to sorbent structural platform, this review provides a critical framework for interpreting analytical performance, informing the rational design of advanced sorbents, and supporting the development of miniaturized solid-phase extraction techniques for food analysis. Full article

High-salinity waters, including seawater, brines, and saline radioactive effluents, contain recoverable uranium or require uranium removal, but their complex chemistry complicates both capture and regeneration. Under seawater-relevant conditions, U(VI) occurs mainly as uranyl carbonate complexes and ternary uranyl carbonate complexes containing Ca²⁺ or Mg²⁺ rather than as free UO₂²⁺. Selective separation therefore depends on coupled transport, hydration-shell reorganization, carbonate displacement, and interfacial coordination. Conventional sorbents largely optimize binding strength and adsorption capacity, often at the expense of harsh stripping and secondary waste. This review frames thermoresponsive uranium separation as a coupled aqueous-speciation, interfacial-state, and process-design problem. It examines how LCST and UCST transitions, polymer-brush reorganization, hydration-layer reconstruction, pore gating, and localized photothermal heating regulate access to binding sites and release pathways. Polymer brushes, hydrogels and microgels, membranes and nanochannels, ion-imprinted magnetic composites, and MXene-based hybrids are critically compared using cycle-level criteria, including U/V selectivity, switching time, regeneration demand, energy input, fouling resistance, material loss, synthesis reproducibility, and environmental performance. Particular emphasis is placed on distinguishing genuine structural gating from the generic effects of temperature on diffusion, ligand exchange, and adsorption equilibria. Current evidence supports the feasibility of programmable capture–release interfaces but remains limited by matrix-dependent transition windows, incomplete mechanistic attribution, scarce quantitative energy and temperature-gradient data, short cycling tests, and limited device-scale validation. Progress will require standardized testing in realistic saline matrices and complete capture–release mass and energy balances rather than evaluation by maximum adsorption capacity alone. Full article

Carbon dioxide (CO₂) capture through adsorption using porous materials has emerged as a promising strategy for mitigating industrial greenhouse gas emissions. However, selecting an optimal adsorbent material under varying operating conditions remains a complex and time-consuming process when relying solely on experimental studies. In this project, a machine-learning-based framework is developed to predict CO₂ adsorption capacity and identify the most suitable adsorbent material using process and material parameters. A comprehensive dataset was constructed comprising multiple classes of adsorbent materials including activated carbon, zeolites, metal–organic frameworks (MOFs), porous organic polymers (POPs), alumina/silica, and amine-functionalized sorbents. The dataset includes key parameters such as temperature, pressure, CO₂ mole fraction, humidity, BET surface area, micropore characteristics, amine loading, heat of adsorption, particle density, pellet diameter, and bed void fraction. Two machine learning models based on the XGBoost algorithm were implemented. An XGBoost Regressor was used to predict the experimental CO₂ adsorption capacity, while an XGBoost Classifier was trained to identify the type of adsorbent used based on the input parameters. The models were trained and validated using a train–test split approach to ensure reliable performance evaluation. The results demonstrate that gradient boosting models can accurately capture complex nonlinear relationships between adsorption conditions, material properties, and adsorption performance. The developed framework provides a fast and efficient predictive tool that can assist researchers and engineers in screening adsorbent materials and optimizing CO₂ capture systems for industrial applications. Using this model, one can predict the adsorption capacity of any adsorbent used in the training dataset and predict its type with 95% accuracy. Full article

Metanephrine (MN) and normetanephrine (NMN) are critical biomarkers for neuroendocrine tumors (pheochromocytoma and paraganglioma). Following our previous development of a molecularly imprinted solid-phase extraction (MISPE) sorbent for urine analysis, this study evaluated MISPE coupled with HILIC-MS/MS for determining metanephrines in human plasma. Unlike conventional phases, the novel polymer selectively binds analytes as in situ-generated anions via quaternary alkylammonium groups in hydroxide form, ensuring accurate extraction from just 25 µL of plasma. Validated per U.S. FDA guidelines, the assay showed good intra- and interday precision (CV < 10.8%), accuracy (bias < −10.6%) and excellent linearity (R² > 0.99) across pathological ranges (184.3–877.8 ng/L for MN; 174.8–923.0 ng/L for NMN), with low relative standard errors (<6.9%). Excellent selectivity was demonstrated in the presence of structurally close analogs (catecholamines, DOPA and its derivatives). Compared with commercial WCX, the sorbent yielded cleaner extracts, significantly reducing the phospholipid interference. Although lower limits of quantification (92.2 ng/L MN; 87.4 ng/L NMN) slightly exceeded healthy upper thresholds, the method has potential for use in specific clinical scenarios with pronounced biomarker elevations: diagnosis of pheochromocytoma/paraganglioma, monitoring post-treatment metanephrine decline, and tracking tumor-induced hypertensive crises in emergencies. This accessible protocol forms a solid foundation for advanced diagnostics. Full article

The scientific literature lacks sufficient data on the transport of various toxic pollutants by polymer particles. Investigating how the structure of microplastic particles formed during the degradation of polymeric materials affects pollutant sorption processes will improve our ability to predict environmental behavior. General-purpose polystyrene, expanded polystyrene, ABS plastic (acrylonitrile–butadiene–styrene) and crosslinked polystyrene are produced on an industrial scale. Copolymers of styrene with divinylbenzene are used on a large scale as sorbents for gel permeation chromatography (Styragel brand sorbents), in the production of catalysts on a polymer substrate or ion-exchange resins. In this study, non-spherical, crosslinked polystyrene microparticles with varying polystyrene chain packing densities were used as model microplastic particles representative of crosslinked polystyrene. It was shown that the adsorption of a hazardous chemical rhodamine B was influenced by both the packing density of the polystyrene chains and the presence of ionic functional groups, i.e., the “degree of aging” of the microplastic particles. The sorption capacities of these model microparticles were compared with those of natural origin (silicon dioxide, quartz powder, and microcrystalline cellulose). A viability assay using HEK293 and HeLa cell lines exposed to leachates from both pristine and rhodamine B-loaded microparticles revealed that all unmodified microparticles, regardless of their nature, exhibited no cytotoxicity at concentrations up to 1000 μg/mL. In contrast, microparticles with adsorbed rhodamine B significantly reduced cell viability to 20–40% at concentrations of 100 μg/mL. Full article

For the removal of hexavalent chromium [Cr(VI)] from drinking water, a hybrid biosorbent designated chitosan–natural diatomaceous earth (CNDE) was developed and thoroughly characterized. The material couples the ion-exchange and chelating capacity of chitosan—applied at an 85% degree of deacetylation—with the high-surface-area mineral framework of natural diatomaceous earth, onto which the polymer was deposited as a conformal coating. Surface morphology and internal microstructure were examined by scanning and transmission electron microscopy (SEM/TEM), while elemental composition across the hybrid matrix was resolved by energy-dispersive X-ray spectroscopy (EDX). Fourier transform infrared (FTIR) spectroscopy was employed to identify the surface functional groups responsible for chromate binding, and streaming current measurements established the pH of zero charge (pH_pzc), which governs the electrostatic environment at the sorbent–solution interface. Specific surface area was quantified by the Brunauer–Emmett–Teller (BET) method, and the balance of surface acidic and basic sites was determined through titrimetric analysis of total acidity and alkalinity. Thermogravimetric analysis (TGA) was conducted to assess thermal stability. Batch equilibrium isotherm experiments were performed to evaluate Cr(VI) uptake from model drinking water prepared using dilute potassium dichromate solutions adjusted to target pH levels. The effects of solution pH and competing anions (chloride and sulfate) were also investigated. Kinetic studies were conducted to determine the rate of Cr(VI) adsorption, and residual metal concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). Results indicated that CNDE containing 30% chitosan (CNDE30) achieved effective Cr(VI) removal at pH 5. Adsorption was strongly pH-dependent, decreasing as pH increased from 5 to 8. Equilibrium data were well described by both Langmuir and Freundlich isotherm models, while kinetic data followed a pseudo-second-order model. The presence of chloride ions (15 mg/L) reduced adsorption capacity by approximately one-third, whereas sulfate at the same concentration significantly inhibited Cr(VI) removal. Overall, the isotherm results suggest that CNDE30 is a promising material for Cr(VI) removal from drinking water. Its cost-effectiveness, ease of synthesis, and potential for reuse make it particularly attractive for small-scale and decentralized water treatment applications. Full article

Porous glycidyl methacrylate-based copolymers crosslinked with ethylene glycol dimethacrylate (EGDMA) and trimethylolpropane trimethacrylate (TMPTMA) were synthesized via suspension–emulsion polymerization and subsequently functionalized with triethylenetetramine. The effect of the monomer composition on the epoxy group content and porous structure was systematically investigated by varying the GMA-to-crosslinker molar ratio from 1:1 to 5:1. Increasing the GMA fraction enhanced the epoxy group content (2.8–5.0 mmol/g) but significantly reduced the specific surface area (333–23 m²/g), indicating a trade-off between functionality and porosity. ATR-FTIR and elemental analysis confirmed successful amine functionalization while preserving a considerable degree of porosity. The modified copolymers were evaluated for Cr(VI) removal, showing strong pH dependence, with maximum efficiency at pH 3 due to electrostatic interactions between protonated amine groups and HCrO₄⁻ ions. Equilibrium studies revealed saturation-type behavior, with a maximum sorption capacity of 165.47 mg/g for TMPTMA-based copolymers. Despite the higher nitrogen content in EGDMA-based materials, TMPTMA-crosslinked copolymers exhibited a superior adsorption performance, demonstrating that pore accessibility, rather than functional group density alone, governs adsorption efficiency. These findings provide insight into the rational design of amine-functionalized porous polymer sorbents for efficient chromium(VI) removal. Full article

This review analyzes the advances over a five-year period in the development of polymeric sorbents for the purification of aqueous media from key classes of pollutants: hydrocarbons (crude oil, diesel fuel), organic dyes, pharmaceuticals (antibiotics), pesticides, herbicides, volatile organic compounds, and polycyclic aromatic hydrocarbons. Attention is paid to the analysis of structure-property-performance relationships, with an emphasis on comparing materials derived from renewable natural feedstocks (such as cellulose, chitosan, terpenes, vegetable oils, and aloe vera) with synthetic polymers. The analysis reveals that biopolymer-based sorbents exhibit comparable or superior sorption capacities combined with environmental safety, biodegradability, and low cost. The key sorption mechanisms include physical adsorption, hydrophobic interactions, and electrostatic interactions. Despite persisting challenges related to scalability, stability in real-world environments, and the need for efficient regeneration protocols, a convergent approach that combines the advantages of modified natural polymers and functional synthetic components appears to be the most promising strategy for developing cost-effective and sustainable technologies for the restoration of water quality. Full article

The aim of this study was to produce and characterize a magnetic biocomposite based on aspen biochar, sodium alginate, and Phaffia rhodozyma yeast biomass, as well as to evaluate its suitability for removing methylene blue (MB) from aqueous solutions. The sorbent structure was confirmed by FTIR, XRD, and SEM, demonstrating successful immobilization of biotic components in an amorphous polymer matrix. Kinetic studies demonstrated a rapid process, with dynamic equilibrium established after 180 min. Experimental data from equilibrium studies (3 h and 24 h) were analyzed using the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models. The theoretical maximum sorption capacity (q_d) determined was 39.31 mg/g, with higher sorption values observed for 24 h confirming the contribution of intrapore diffusion and yeast biosorption activity. In temperature-effect studies, the highest process efficiency (q_e = 1.43 mg/g) was observed at 25 °C, while its decrease at 35 °C indicated the exothermic nature of the phenomenon and the thermal sensitivity of the biological structure. VSM analysis revealed superparamagnetic properties of the composite (Ms = 9.3 A·m²/kg), which enabled full phase separation. Regeneration studies demonstrated that despite the high efficiency of mineral acids, the use of ethanol as an eluent allows for maintaining the structural integrity of the sorbent and its effective use in at least four cycles. The results indicate that the developed biocomposite is a promising, low-cost, and easily recoverable alternative to conventional sorbents in industrial wastewater treatment technologies. Full article

Anthropogenic phosphorus (P) release from human activities continues to degrade freshwater systems, underscoring the need for effective and sustainable approaches to P removal and management. This study investigates steel slag–chitosan–nanoclay hydrogel composites as a waste-derived alternative to metal-doped biopolymer hydrogels for P removal from wastewater and stormwater. Steel slag aggregates (SSAs), a by-product of steel manufacturing, were incorporated into chitosan-based hydrogel matrices to produce composite sorbents derived from waste materials with potential for cost-effective application. Two formulations (SSA20 and SSA40) were synthesized and compared with a chitosan–nanoclay–iron (CH/NC/Fe) reference hydrogel. Phosphorus adsorption affinity was evaluated using a standardized 24 h batch protocol at environmentally relevant concentrations representative of municipal wastewater (10 mg P L⁻¹) and stormwater or agricultural runoff (1 mg P L⁻¹). The SSA40 composite exhibited the highest P adsorption affinity (Rd = 2.39 ± 0.22 L g⁻¹), outperforming both standalone SSA and the Fe-based hydrogel reference. Scanning Electron Microscopy and Energy-Dispersive X-Ray Spectroscopy (SEM–EDX) analyses revealed strong polymer–slag interactions and metal–phosphate associations, consistent with coupled adsorption and precipitation mechanisms. The SSA-based hydrogels also exhibited self-induced acidification (pH 3.3–4.2), enhancing phosphate uptake while providing intrinsic pH buffering. This study introduces a stable, waste-derived hydrogel composite and demonstrates a reproducible, environmentally relevant batch-testing approach for comparative evaluation of hydrogel phosphorus sorbents, supporting evidence-based strategies for sustainable phosphorus pollution control. Full article

The release of CO₂ gas into the atmosphere is one of the most prolific causes of global climate change. To solve this problem, cost-effective technologies are being sought. Polymer membranes are innovative materials that can be widely used in the process of capturing and separating CO₂ gas. In this work, an amine impregnated and amidated solid sorbent (AISS) containing a copolymer (PMMA-co-AA), which consists of acrylic acid (AA) and methyl methacrylate (MMA), and PEPA (polyethylene polyamine), was synthesized. For the first time, sorbents based on homopolymers and copolymers of acrylic acid and methyl methacrylate were compared for their ability to capture CO₂ gas. Other than the synthesis of low swelling AISS, a calculation of its energy consumption, and a comparison of its cyclic capacity with 30% water solutions of monoethanolamine and methyldiethanolamine (MEA and MDEA) were performed. The solid sorbent PMMA-co-AAS showed a higher cyclic capacity than others, corresponding to the order PMMA-co-AAS (23 mg/g) > PAAS (16 mg/g) > MDEA (10 mg/g) > MEA (6 mg/g). The average absorption rate for these sorbents was in the sequence of MEA > PMMA-co-AAS > PAAS > MDEA at 40 °C, and the desorption rates were PMMA-co-AAS > PAAS > MDEA > MEA for these sorbents at 70 °C, correspondingly. When the amount of acrylic acid in the copolymer was varied from 0 to 100%, the copolymer’s water absorption capacity ranged from 0.2 to 1359.63%. Among them, the swelling ability of the chosen sorbent prepared from the 10% AA-containing copolymer and PEPA was 0.64%. Full article

To address the limited selectivity of conventional membrane materials toward sulfonamide antibiotics, this study employed a DFT calculation approach to optimize the design of a molecularly imprinted system for sulfadiazine (SDZ). A hierarchical set of template molecules—aniline (ANL), sulfanilamide (SNM), and SDZ—was introduced to systematically elucidate structure-dependent template–monomer matching mechanisms in sulfonamide imprinting systems. Through rational screening, trifluoroethyl methacrylate (TFEMAA) was identified as the optimal functional monomer, with an optimal imprinting molar ratio of 1:4 (SDZ to TFEMAA). Guided by the simulation results, SDZ molecularly imprinted polymers (MIPs) were synthesized via precipitation polymerization and systematically characterized for their morphology and recognition properties. The MIPs exhibited a well-defined spherical morphology with abundant imprinted cavities, achieving adsorption equilibrium within 1.5 h. The adsorption kinetics followed a pseudo-second-order model, indicating a chemisorption-dominated process. Scatchard analysis revealed the presence of both high- and low-affinity binding sites in the MIPs. Selectivity experiments, quantified by distribution coefficients (K_d) and selectivity coefficients (k), demonstrated a significantly higher adsorption capacity for SDZ than for structural analogs and non-analogs. In real water samples, the MIPs outperformed conventional HLB sorbents and showed strong anti-interference capability (RSD < 3%). This work provides a material foundation for developing highly selective SDZ-imprinted membranes and advances the application of molecular imprinting technology in membrane separation systems. Full article

In this study, core–shell molecularly imprinted polymers (CS-MIP) were utilized for the detection of the herbicide S-metolachlor in surface water samples, collected from a river and pond that are in the proximity of cornfields. The study revealed that no traces of herbicide were detected in the samples that were analyzed. The collected water samples were treated with membrane filtration—microfiltration and ultrafiltration. The adsorption isotherms were fitted using the Langmuir, Freundlich, Dubinin–Radushkevich, and Scatchard models. This indicated that the Scatchard model is the most appropriate for CS-MIP. The data obtained from the kinetic study were analyzed using the pseudo-first-order and pseudo-second-order models, as well as Fick’s second law. For CS-MIP, the most suitable model was determined to be the particle diffusion model, while for core–shell non-imprinted polymers (CS-NIP), the film diffusion model was identified as the limiting step. A method for the desorption of S-metolachlor from the pH-sensitive sorbent bed has been developed, thereby enabling the material to be reused. The optimum eluent from the multicomponent solution was determined to be a 30% aqueous ethanol solution with a pH of approximately 9. This solution effectively removed the majority of contaminants, with the exception of S-metolachlor, which was retained within polymer pores. Full article

In this study, magnetic porous glycidyl methacrylate and ethylene glycol dimethacrylate copolymer (mP) grafted with tetraethylenepentamine (mP-TEPA) obtained in a two-step procedure was tested as the CO₂ sorbent. The morphological, textural, structural, and thermal characterization of the sample was determined by scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDS), mercury intrusion porosimetry (MIP), nitrogen physisorption at 77 K, Fourier transform infrared spectroscopy in ATR mode (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), elemental analysis, and thermogravimetric analysis (TGA). The effects of thermodynamic and kinetic parameters, as well as the adsorption/desorption mechanism on the CO₂ sorption ability of mP-TEPA, were investigated using a pulse gas chromatographic method. Under optimal adsorption conditions, the CO₂ sorption capacity reached 6.20 mmol CO₂/g (6.20 × 10⁻² mmol CO₂/m²). Temperature-programmed desorption (TPD) experiments were conducted to calculate the activation energy of CO₂ desorption. The low desorption activation energy of 18.80 kJ/mol and high desorption rate, with stable CO₂ uptake after ten adsorption/desorption cycles, suggest that mP-TEPA is a potentially excellent sorbent for CO₂ adsorption. Full article