Search Results (357)

Polymeric membranes are a highly viable technology for wastewater treatment, water purification, and other filtration operations. Accordingly, flat membranes were developed from extruded nanocomposites of polyamide 6 (PA6) and carbon nanotubes (MWCNT), varying the filler content to 1, 3, and 5 parts per hundred resin (phr). The membranes were produced using the phase inversion process through the immersion–precipitation technique. In total, eight membrane compositions were developed with solvent/polymer ratios of 80/20 (weight %). Calcium chloride (CaCl₂) was used as a pore-forming agent at a content of 10 phr. Thus, the characterizations performed were: solution viscosity, FTIR, contact angle measurement, SEM, AFM, water permeability test, and water vapor permeation test. The results showed that the high viscosity of membranes, excessive gelation time, and higher MWCNT contents contributed to a decrease and/or absence of flow. Through SEM images and water flow measurements, the significant influence of CaCl₂ was observed in modifying the membrane morphology (more interconnected porous structures), ensuring the presence of flow. The AFM images also confirm this phenomenon through the increase in roughness. Water vapor transmission increased with higher MWCNT content. These results demonstrate that PA6 and MWCNT membranes were effective for water filtration, only in those where CaCl₂ was used, and for water vapor initially. Full article

Seedling establishment on reclaimed boreal sites is frequently constrained by drought and other abiotic stresses. Carbon nanomaterials have been shown to influence stress physiology in crops, but their effects on native boreal species are poorly understood. We tested whether carboxylic acid-functionalized multi-walled carbon nanotubes (MWCNTs) alter drought responses in three shrubs widely used in reclamation: Shepherdia canadensis (L.) Nutt, Cornus sericea L., and Viburnum edule. Seedlings received two irrigations with MWCNTs suspensions (0 (control), 10, or 30 mg L⁻¹) before exposure to well-watered or drought conditions in a greenhouse. Drought reduced photosynthesis, stomatal conductance, and transpiration and increased Ci/Ca across species, consistent with declining leaf water potential. MWCNTs did not broadly modify these responses, but the highest concentration (30 mg L⁻¹) further suppressed stomatal conductance in C. sericea and V. edule during mid- to late drought. S. canadensis showed little responsiveness. These effects suggest that MWCNT-associated stomatal closure may limit water loss under stress but also constrain CO₂ uptake, offering no clear photosynthetic benefit. MWCNT impacts were subtle, species- and dose-dependent, and centered on stomatal regulation. Application in reclamation should therefore be approached cautiously, balancing potential water-saving benefits against possible reductions in carbon assimilation and growth. Full article

In this work, pCh-MWCNTs@Ag-TiO₂/S and pCh-MWCNTs@Ag-TiO₂ nanocomposites were synthesized through a combined phosphorylation and cross-linked polymerization method. The materials were thoroughly characterized using several analytical techniques, including SEM/EDS, FTIR, TGA, and BET analysis. SEM images revealed that the pCh-MWCNTs@Ag-TiO₂/S nanocomposite displayed a smooth, flake-like morphology with spherical, dark greenish particles. EDS analysis confirmed the presence of Si, S, P, and Ag as prominent elements, with Ti, C, and O showing the most intense peaks. The TGA curves indicated significant weight loss between 250–610 °C for pCh-MWCNTs@Ag-TiO₂ and 210–630 °C for pCh-MWCNTs@Ag-TiO₂/S, corresponding to the decomposition of organic components. FTIR spectra validated the existence of functional groups such as hydroxyl (-OH), carboxyl (-COOH), and carbonyl (-C=O) on the surface of the nanocomposites. Following characterization, the materials were evaluated for their capacity to adsorb Hg²⁺ at parts-per-billion (ppb) concentrations in contaminated water. Batch adsorption experiments identified optimal conditions for mercury removal. For pCh-MWCNTs@Ag-TiO₂, the best performance was observed at pH 4, with an adsorbent dose of 4.0 mg, initial mercury concentration of 16 ppb, and a contact time of 90 min. For pCh-MWCNTs@Ag-TiO₂/S, optimal conditions were at pH 6, a dosage of 3.5 mg, the same initial concentration, and a contact time of 100 min. Each parameter was optimized to determine the most effective conditions for Hg²⁺ removal. The nanocomposites showed high efficiency, achieving more than 95% mercury removal under these conditions. Kinetic studies indicated that the adsorption process followed a pseudo-second-order model, while the equilibrium data aligned best with the Langmuir isotherm, suggesting monolayer adsorption behavior. Overall, this research highlights the effectiveness of sulfur-modified chitosan-based nanocomposites as eco-friendly and efficient adsorbents for the removal of mercury from aqueous systems, offering a promising solution for water purification and environmental protection. Full article

A novel two-domain small laccasefrom Streptomyces ochraceiscleroticus (SoSL) was produced through recombination in Escherichia coli and purified by affinity chromatography. The properties (thermal optimum and thermostability, pH optima and pH-stability), kinetic characteristics, substrate specificity and dye decolorization ability were estimated. Laccase SoSL was able to oxidize 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS)and 2,6-dimethoxyphenol (2,6-DMP) with at a maximal rate at pH 3.5 and 9.0, respectively, and was stable at pH 9.0 (retained 75% activity after incubation at room temperature for 120 h). High enzyme affinity to ABTS is caused by an expanded area occupied by aromatic amino acid residues on its surface. Substrate-directed immobilization of the enzyme was performed using naphthylated multiwalled carbon nanotubes (MWCNTs), and a high oxygen reduction reaction potential (+0.62 V vs. normal hydrogen electrode (NHE)) was observed. The above-mentioned features make this enzyme a promising one for further studies in bioremediation and biological fuel cell technologies. Full article

A series of studies was conducted on the functional and structural characteristics of polymer composite materials (PCMs) based on silicone polymers modified with multi-walled carbon nanotubes (MWCNTs) and metallic particles (CuAl or Al). The influence of the structural parameters of carbon and metallic inclusions in the polymer matrix on the electrophysical and thermophysical properties of the composites was demonstrated. Various conduction mechanisms dominating in the inverse temperature ranges of 50 K^–1–13 K^–1, 13 K^–1–6 K^–1, and 6 K^–1–2 K^–1 were identified. The operational modes of the polymer composites as active materials for thermoregulating coatings were established. The highest temperature of 32.9 °C in operating mode and the shortest warm-up time of 180 s were observed in the composite modified with 4 wt.% CNTs and 10 wt.% bronze particles at a supply voltage of 10 V. The characteristics of the composites under atomic oxygen (AO) exposure with a fluence of 3 × 10²¹ atoms/cm² was evaluated, confirming their functionality, particularly for potential space applications. The composites demonstrated nearly complete retention of their functional characteristics. The aim of this study was to develop electrically conductive functional composites based on silicone polymers containing MWCNTs and metallic particles inclusions for creating electric heating elements with tailored functional characteristics. Full article

The growing scarcity of freshwater worldwide has increased interest in forward osmosis (FO) membranes as a promising solution for water desalination and wastewater treatment. This study investigates the enhancement of thin-film composite (TFC) FO membranes via the incorporation of carboxyl-functionalized multiwalled carbon nanotubes (COOH-MWCNTs) into the polyethersulfone (PES) support layer. The membranes were fabricated using a combination of phase inversion and interfacial polymerization techniques, with COOH-MWCNTs incorporated into the membrane support layers at different concentrations (0–0.75 wt.%). Comprehensive characterization was carried out using various analytical methods and mechanical testing to evaluate the physicochemical and structural properties of the membranes. The modified membranes demonstrated improved hydrophilicity, enhanced mechanical and thermal stability, and improved surface charge properties. Performance tests using a 1 M NaCl draw solution showed that the optimized membrane (0.5 wt.% COOH-MWCNTs) attained a 161% enhancement in water flux (7.48 LMH) compared to the unmodified membrane (2.86 LMH), while also reducing internal concentration polarization (ICP). The antifouling properties were also significantly improved, with a flux recovery rate of 91.92%, attributed to enhanced electrostatic repulsion as well as surface and microstructural modifications. Despite a moderate rise in reverse solute flux, the specific reverse solute flux (J_s/J_w) remained within acceptable limits. These findings highlight the potential of COOH-MWCNT-modified membranes in enhancing FO desalination performance, offering a promising option for next-generation water purification technologies. Full article

Pseudo-persistent organic pollutants, such as pharmaceuticals, personal care products (PPCPs), and organic dyes, are a major issue in current environmental engineering. Considering the limitations of traditional wastewater treatment plant methods and degradation technologies for organic pollutants, the search for new technologies more suitable for treating these new types of pollutants has become a research hotspot in recent years. Membrane filtration, adsorption, advanced oxidation, and electrochemical advanced oxidation technologies can effectively treat new organic pollutants. The electro-advanced oxidation process based on sulfate radicals is renowned for its non-selectivity, high efficiency, and environmental friendliness, and it can improve the dewatering performance of sludge after wastewater treatment. Therefore, in this study, octyl methoxycinnamate (OMC) was selected as the target pollutant. A new type of electrochemical filtration device based on the advanced oxidation process of sulfate radicals was designed, and a new type of modified carbon nanotube material electrode was synthesized to enhance its degradation effect. In a mixed system of water and acetonitrile, the efficiency of the electrochemical filtration device loaded with the modified electrode for degrading OMC is 1.54 times that at room temperature. The experimental results confirmed the superiority and application prospects of the self-designed treatment scheme for organic pollutants, providing experience and a reference for the future treatment of PPCP pollution. Full article

A novel type of multifunctional hybrid membranes combining modified chitosan, functionalized multi-walled carbon nanotubes (MWCNTs), and rare earth element ion-imprinted polymers (REEIIPs) were designed and characterized. The synthesized materials were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), X-ray diffraction (XRD), X-ray micro-tomography, and Fourier transform infrared spectroscopy (FTIR). The hybrid membranes were also studied in terms of their mechanical and rheological properties. The key element of the proper preparation of hybrid membranes using the casting method in an external magnetic field was to synthesize membrane components with appropriate magnetic properties. It was found that they showed tunable weak ferromagnetic properties, and the increase in modified nanotube addition caused the rise in the membrane’s saturation magnetization, which for Nd-selective hybrid membranes reached 0.44 emu/g. Also, the increase in thermooxidative stability was noted after introducing functionalized nanotubes into polymer matrices, which, in the case of Gd-selective membranes, were stable even up to 730 °C. The rise in the modified MWCNT addition and selection of appropriate REE ion-imprinted polymers improved mechanical (Rm and E values increase even twice) and rheological parameters (almost double growth of E′ and E″ values) of the tested membranes. Synthesized hybrid membranes showed a high rejection of matrix components and an increase in retention ratio with rising MWCNT-REEIIP addition, ultimately reaching 94.35%, 92.12%, and 90.11% for Nd, Pr, and Gd, respectively. The performed analysis confirmed homogeneous dispersion, phase compatibility, network integration, formation of a complex 3D microstructure, and improved operational stability of created hybrid membranes, which is significant for their future applications in Nd, Pr, and Gd recovery from coal fly ash extracts. Full article

This study explores using polyvinylidene fluoride (PVDF) membranes modified with multi-walled carbon nanotubes (MWCNTs) to treat simulated and industrial brine from coal power stations. The MWCNTs were acid-treated and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Raman, and nitrogen sorption at 77 K, Thermogravimetric analysis (TGA), and Transmission electron microscopy (TEM). The desired membranes were obtained by casting from a solution of N-Methyl-2-pyrrolidone, PVDF, various weight percentages of MWCNTs, and a small amount of polyvinylpyrrolidone. The acid treatment of the MWCNTs introduced oxygen moieties on the surface, and increased pore volume and surface area while maintaining crystallinity and structural integrity remain preserved. The maximum rejection rate achieved was 41.82% with 1 wt.% of acid-treated MWCNTs in the PVDF membrane. Acid-treated MWCNTs loaded membranes had an improved rejection rate, which was 5× higher than membranes without MWCNTs. Full article

Bisphenol S (BPS), a key ingredient in polycarbonate plastics and epoxy resins, is a known endocrine-disrupting compound that poses significant risks to human health and the environment. As such, the development of rapid and reliable analytical techniques for its detection is essential. In this work, we present a newly engineered electrochemical sensor designed for the sensitive and selective detection of BPS using a straightforward and effective fabrication approach. The sensor was constructed by grafting molecularly imprinted polymers (MIPs) onto vinyl-functionalized multiwalled carbon nanotubes (f-MWCNTs). Ethylene glycol dimethacrylate and acrylamide were used as the cross-linker and functional monomer, respectively, in the synthesis of the MIP layer. The resulting MIP@f-MWCNT nanocomposite was characterized using Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The MIP@f-MWCNT material was then combined with chitosan, a biocompatible binder, to fabricate the final MIP@f-MWCNT/chitosan-modified glassy carbon electrode (GCE). Electrochemical evaluation showed a broad linear detection range from 1 to 60 µM (R² = 0.992), with a sensitivity of 0.108 µA/µM and a detection limit of 2.00 µM. The sensor retained 96.0% of its response after four weeks and exhibited high selectivity against structural analogues. In spiked plastic extract samples, recoveries ranged from 95.6% to 105.0%. This robust, cost-effective, and scalable sensing platform holds strong potential for environmental monitoring, food safety applications, and real-time electrochemical detection of endocrine-disrupting compounds like BPS. Full article

Hydroxychloroquine (HCQ), a cornerstone therapeutic agent for autoimmune diseases, requires precise serum concentration monitoring due to its narrow therapeutic window. Current HCQ monitoring methods such as HPLC and LC-MS/MS are sensitive but costly and complex. While electrochemical sensors offer rapid, cost-effective detection, their large chambers and high sample consumption hinder point-of-care use. To address these challenges, we developed a microfluidic electrochemical sensing platform based on a screen-printed carbon electrode (SPCE) modified with a hierarchical nanocomposite of gold nanoparticles (AuNPs), copper-based metal–organic frameworks (Cu-MOFs), and multi-walled carbon nanotubes (MWCNTs). The Cu-MOF provided high porosity and analyte enrichment, MWCNTs established a 3D conductive network to enhance electron transfer, and AuNPs further optimized catalytic activity through localized plasmonic effects. Structural characterization (SEM, XRD, FT-IR) confirmed the successful integration of these components via π-π stacking and metal–carboxylate coordination. Electrochemical analyses (CV, EIS, DPV) revealed exceptional performance, with a wide linear range (0.05–50 μM), a low detection limit (19 nM, S/N = 3), and a rapid response time (<5 min). The sensor exhibited outstanding selectivity against common interferents, high reproducibility (RSD = 3.15%), and long-term stability (98% signal retention after 15 days). By integrating the nanocomposite-modified SPCE into a microfluidic chip, we achieved accurate HCQ detection in 50 μL of serum, with recovery rates of 95.0–103.0%, meeting FDA validation criteria. This portable platform combines the synergistic advantages of nanomaterials with microfluidic miniaturization, offering a robust and practical tool for real-time therapeutic drug monitoring in clinical settings. Full article

In this study, an electrochemical method is presented for the direct determination of tyramine in beer samples. A multi-walled carbon nanotubes (MWCNTs) modified glassy carbon electrode (GCE) was developed for the detection and quantification of tyramine at a low potential of 0.53 V. The electrochemical process and sensor parameters were thoroughly investigated to establish optimal analysis conditions. The method demonstrated a linear response range from 3 to 9 µM, with a limit of detection (LOD) of 0.34 µM and a limit of quantification (LOQ) of 1 µM. The developed sensor was successfully applied to commercial beer samples for tyramine analysis. The results were compared with those obtained using the standard high-performance liquid chromatography (HPLC) technique, highlighting the sensor’s potential for tyramine determination in aqueous food samples without the need for complex sample preparation. Full article

The objective of this study is to explore the high-temperature rheological properties and microscopic interaction mechanisms of styrene–butadiene–styrene (SBS) composite-modified asphalt with hydroxylated multi-walled carbon nanotubes (MWCNT-OH). SBS-modified asphalt, MWCNT-modified asphalt and MWCNT/SBS composite-modified asphalt were prepared with high-speed shearing apparatus and machine mixer. Physical property tests, dynamic shear rheological (DSR) tests, multiple stress creep recovery (MSCR) tests, X-ray diffraction (XRD) and Raman spectroscopy analyses were carried out to systematically compare the differences in macroscopic performance and changes in microscopic structure of different types of asphalts. According to the results of physical property tests, DSR tests and MSCR tests, the composite-modified asphalt was superior to the single-component-modified asphalt in terms of complex modulus (G*) and rutting factor (G*/sin δ). Its creep recovery rate (R) and unrecoverable compliance (Jnr) exhibited better anti-deformation ability under high temperatures, verifying the synergistic effect of SBS and MWCNTs-OH. XRD analysis showed that composite modification reduced the disorder degree of the crystalline phase of asphalt. Raman spectroscopy confirmed that there were changes in the vibration of chemical bonds between the modifier and asphalt, indicating that the modifier and asphalt acted on the asphalt system through physical dispersion and chemical cross-linking. Full article

Pulmonary exposure to carbon nanotubes (CNTs) has been linked to a series of adverse respiratory effects in animal models, including inflammation, genotoxicity, fibrosis, and granuloma formation, the degree and characteristics of which are considered dependent upon the detailed physicochemical properties of the material as inhaled. To further explore the effect of variations in physicochemical properties on pulmonary effects, two different multi-walled CNTs (MWCNTs) were tested in vivo: a pristine MWCNT (pMWCNT) (NM-401) and a surface-modified MWCNT (MWCNT-COOH). Female Sprague–Dawley rats were whole-body exposed for 28 days to MWCNT aerosols (pMWCNT (0.5 and 1.5 mg/m³) and MWCNT-COOH (1.5 and 4.5 mg/m³)) and followed up to 1 year post-exposure. The inhalation exposures resulted in relatively low estimated lung deposition. Bronchoalveolar lavage fluid (BALF) analysis indicated inflammation levels broadly consistent with deposited dose levels. Lung histopathology indicated that both MWCNTs produced very limited toxicological effects; however, global mRNA expression levels in lung tissue and BALF cytokines indicated different characteristics for the two MWCNTs. For example, pMWCNT but not MWCNT-COOH exposure induced osteopontin production, suggestive of potential pre-fibrosis/fibrosis effects linked to the higher aspect ratio aerosol particles. This is of concern as brightfield and enhanced darkfield microscopy indicated the persistence of pMWCNT fibres in lung tissue. Full article

Diblock copolymers (BCP) consisting of poly(methyl methacrylate) (PMMA) and poly(1H,1H,2H,2H-perfluorodecyl methacrylate) (PsfMA) blocks are employed as templates for controlled dispersion and localization of multi-walled carbon nanotubes (MWCNT). Short MWCNT are modified with perfluoroalkyl groups to increase the compatibility between MWCNT and the semifluorinated (PsfMA) phase and to promote a defined arrangement of MWCNT in the BCP morphology. Thin BCP and BCP/MWCNT composite films are prepared by dip-coating using tetrahydrofuran as solvent with dispersed MWCNT. Atomic force microscopy, scanning and transmission electron microscopy reveal a strong tendency of the BCP to form micelle-like domains consisting of a PMMA shell and a semifluorinated PsfMA core, embedded in a soft phase, containing also semifluorinated blocks. MWCNT preferentially localized in the embedding phase outside the micelles. Perfluoroalkyl-modification leads to significant improvement in the dispersion of MWCNT, both in the polymer solution and the resulting nanocomposite film due to increased interaction of MWCNT with the semifluorinated side chains in the soft phase outside the micelle domains. As a result, reliable electrical conductivity is observed in contrast to films with non-modified MWCNT. Thus, well-dispersed, modified MWCNT provide a defined electrical conduction path at the micrometer level, which is interesting for applications in electronics and vapor sensing. Full article