Search Results (1,847)

This study investigates the optimization of fabrication and operating parameters for poly(ether sulfone) (PES) ultrafiltration membranes embedded with Bismuth tungstate and multi-walled carbon nanotubes (MWCNTs) Bi₂WO₆/MWCNTs for the removal of dye pollutants from wastewater. Response surface methodology (RSM) coupled with Analysis of Variance (ANOVA) was employed to develop regression models for evaluating membrane performance in terms of dye rejection and permeate flux. A central composite design (CCD) was used to conduct a systematic series of ultrafiltration experiments. The effects of key variables, including Bi₂WO₆/MWCNTs loading (0–0.1 wt.%), operating pressure (5–9) bar, and methyl red (MR) dye concentration (50–150 ppm), on membrane separation performance were comprehensively examined. The developed models demonstrated strong statistical significance and accurately described the experimental data. Optimization results revealed that the operating parameters exerted a more pronounced influence on membrane performance than fabrication variables. The maximum MR rejection of 96.8457% was achieved at an optimal Bi₂WO₆/MWCNTs loading of 0.08 wt.%, dye concentration of 112.6 ppm, and operating pressure of 9 bar. Experimental validation confirmed the reliability and predictive capability of the proposed models. In order to provide high-performance membranes with enhanced permeability, antifouling resistance, and dye removal efficiency for useful wastewater treatment applications, this study attempts to optimize the operating and preparation parameters for adding Bi₂WO₆/MWCNT nanocomposites into PES membranes. Full article

Growing interest in sustainable, high-performance energy storage has driven extensive studies on advanced electrode materials for supercapacitor applications. In this study, a FeNiCo metal–organic framework/multiwalled carbon nanotube (MOF–MWCNT) composite was synthesized and employed as a modifying layer on a carbon felt electrode (CFE) via a drop-casting method. The electrochemical performance of the composite electrode was systematically evaluated in 1 M H₂SO₄ electrolyte. Structural and electrochemical studies demonstrate that the combined effect of the conductive CFE substrate, the electric double-layer capacitance of MWCNTs, and the pseudocapacitive properties of the trimetallic FeNiCo MOF markedly enhances the charge storage performance. Cyclic voltammetry and galvanostatic charge–discharge measurements demonstrate a maximum specific capacitance of approximately 180 F g⁻¹. The electrode delivers an energy density of 73.20 Wh kg⁻¹ at a power density of 3796.17 W kg⁻¹, demonstrating a favorable balance between energy and power performance. In addition, high coulombic efficiency confirms excellent charge–discharge reversibility. Notably, 71% of the initial capacitance is retained after 900 cycles in 1 M H₂SO₄, indicating stable electrochemical behavior even under strongly acidic conditions. These findings emphasize the promise of the FeNiCo MOF–MWCNT/CFE composite as a durable electrode design for next-generation supercapacitor devices. Full article

Inhalation is a primary route of exposure to engineered nanomaterials (ENMs), enabling particles to penetrate deeply into the lungs and subsequently leading to adverse health effects. Human health risk assessment addresses the potential risk posed by ENMs. The aim was achieved by measuring the emissions of ENMs using real-time instrumentation and subsequently applying the data to evaluate associated human health risks using ModelRisk. Emissions during the synthesis of silver nanoparticles (AgNPs), gold nanoparticles (AuNPs), graphene 2D (G2D) nanomaterials, multiwalled carbon nanotubes (MWCNT) and the application of AuNPs on black carbon electrodes were monitored using a NanoScan SMPS Model 3910 and Optical Particle Sizer (OPS) Spectrometer Model 3330. The derived mass-based time-weighted average concentrations were reported for AgNPs and MWCNTs in comparison with occupational exposure limits (OELs). AgNP concentrations of 0.36 µg/m³ and 3.99 µg/m³ for the NanoScan SMPS and OPS, respectively, exceeded the OEL of 0.19 µg/m³, whereas MWCNT concentrations (0.261 µg/m³) remained below the OEL of 1 µg/m³. AuNP synthesis resulted in particle number concentrations exceeding the provisional nano reference value of 20,000 particles/cm³ for the OPS data (3.74 × 10⁴ particles/cm³), whereas application of AuNPs on carbon black electrodes was below this limit. Although no OEL exists for graphene, risk estimates indicated potential adverse health effects like those observed for AgNPs, AuNPs, and MWCNTs. Measured exposure concentrations were applied in a human health risk assessment model, highlighting ENM concentration as a key determinant of risk. These findings emphasise the need for continuous monitoring, further risk assessment studies, and proactive risk management strategies. Full article

Ionic polymer–metal composites consist of an ion-conducting polymer–gel membrane sandwiched between two flexible electrodes, representing a class of soft electroactive materials capable of large deformation under low voltage. The gel membrane, swollen with solvent, facilitates ion migration under an electric field, enabling actuation. Tailoring the interfacial architecture between the electrode and the polymer–gel membrane is pivotal for advancing high-performance IPMC actuators. This study presents a comparative investigation of three core–shell nanocomposite electrodes, fabricated via in situ polymerization, for IPMC applications. Among these, the polyaniline-coated multi-walled carbon nanotube composite exhibits a deliberately designed hierarchical structure, with a specific surface area of 32.345 m²·g⁻¹ and a conductive doped polyaniline shell, as confirmed through XPS analysis. This optimized interface enables superior charge storage and transport, endowing the corresponding electrode with a specific capacitance of 40.28 mF·cm⁻² at 100 mV·s⁻¹—3.2 times greater than that of conventional silver-based electrodes—along with a reduced sheet resistance. When integrated with a Nafion ion–gel membrane, the PANI@MWCNT electrode achieves a 67% increase in force density and a larger displacement output compared to standard devices, directly correlated with its enhanced electrical and electrochemical properties. This work highlights the critical role of core–shell interfacial engineering in governing electromechanical performance at the electrode–gel interface and offers a practical design strategy for developing high-performance, cost-effective IPMC actuators for soft robotics, flexible electronics, and related applications. Full article

Polymer nanocomposites offer significant potential for improving the strength-to-weight ratio and dynamic behavior of drone blades. This study examines the vibration characteristics of tapered aramid (Kevlar)/epoxy composite blades reinforced with nanocarbon fillers—graphene (2D), multi-walled carbon nanotubes (MWCNTs, 1D), and fullerene (0D)—to determine the most effective filler for enhancing stiffness and operational stability. The laminated blades (300 mm length, 200 mm width, root thickness 13 mm, tip thickness 8 mm) incorporate ply drop-offs and a central honeycomb core. Modeling was performed using classical laminate plate theory integrated with the finite element method (FEM) in MATLAB (R2016a). Under clamped–free–free–free boundary conditions, the study considered rotational speeds of 750–2250 rpm, setting angles of 30–60°, various fiber orientations, and nanofiller contents of 0–10 wt.%. The results indicate that while the setting angle minimally affects natural frequency, it significantly influences damping in modes (1,2) and (2,1). Increasing nanofiller content improves stiffness, with optimal performance observed near 5 wt.%. At 1500 rpm in mode (1,1), MWCNTs provided the greatest enhancement. Overall, MWCNTs exhibited superior stiffness improvement and rotational stability compared to other fillers. Full article

To mitigate the interlayer defects and weak interfacial adhesion inherent in FFF-printed parts, thereby facilitating subsequent supercritical foaming applications, a microwave-assisted interlayer healing strategy is developed for FFF-printed, supercritical CO₂-foamed thermoplastic polyurethane (TPU) by incorporating aminated helical multi-walled carbon nanotubes (AS-MWCNTs). Owing to their unique helical morphology, AS-MWCNTs exhibit enhanced microwave absorption and localized heating capability, enabling selective thermal activation at interlayer regions within the foamed architecture. Microwave irradiation induces localized softening of the TPU matrix and promotes polymer chain mobility and interdiffusion across layer interfaces, while preserving the cellular morphology and bulk foamed structure. By optimizing AS-MWCNT loading, substantial improvements in interlayer bonding strength, energy absorption, and overall mechanical performance are achieved. This work provides an effective strategy to restore interlayer integrity in supercritical CO₂-foamed, additive manufactured elastomers and offers insights into the design of microwave-responsive, self-healing cellular materials. Full article

For the first time, hybrid nanocomposites based on poly(2,5-dichloro-3,6-bis(phenylamino)-p-benzoquinone) (PCPAB) and multi-walled carbon nanotubes (MWCNTs) were obtained and the influence of the preparation method on their structure and functional properties was demonstrated. The nanocomposites were obtained both by ultrasonic mixing of PCPAB and MWCNTs, and via in situ oxidative polymerization of CPAB in the presence of MWCNTs or MWCNTs with the addition of ZnO. The formation of hybrid nanocomposites occurs due to non-covalent interaction (π-stacking) between the graphene structures of the MWCNT surface and the phenyl rings of PCPAB. It was found that during the in situ oxidative polymerization of CPAB in the presence of MWCNTs, the growth of polymer chains occurred in close proximity to the filler surface, which led to the formation of a polymer coating. ZnO particles, localized on MWCNTs, on the one hand, prevent their aggregation, and on the other hand, create additional polymerization reaction centers due to the coordination of the Zn-O bond at the H and O atoms of the monomer. An increase in the concentration of reaction centers as a result led to a 2–2.5-fold reduction in the induction polymerization period. According to SEM data, in this case, a more ordered and denser polymer layer is formed due to intermolecular complexation between the main and side chains of the growing polymer with the participation of Zn²⁺ ions formed as a result of the transformation of ZnO to ZnCl₂ in the acidic reaction medium of polymerization. The results of the study of the frequency dependences of conductivity indicate a hopping mechanism of conductivity of nanocomposites. The electrical conductivity of nanocomposites depends on their production method and the MWCNT content and varies between 0.5 and 1.1 S∙cm⁻¹, which is 6–12 times higher than the conductivity of the original polymer. Thermogravimetric analysis revealed that the nanocomposites exhibit enhanced thermal stability compared to PCPAB. The best results were shown by nanocomposites with a higher content of MWCNTs, for which the residual mass at 450 °C was 51–53%. Full article

Dopamine (DA) plays an extremely crucial role in the metabolic processes of the human body. Accurate detection of DA is of great significance for many major diseases. This study reports an innovative synthesis method for composite material in which sulfur (S) and nitrogen (N) are incorporated into multi-walled carbon nanotubes (MWCNTs), and platinum (Pt) nanoparticle sensors (Pt/CNTs-N-S) are loaded for the highly sensitive and selective electrochemical detection of DA. The linear range of this sensor is from 0.0078 to 2 mM, and the limit of detection (LOD) is 0.73 μM (S/N = 3) for DA detection. The outstanding detection performance exhibited by Pt/CNTs-N-S is mainly attributed to the co-doping of N and S, which improves the surface properties of MWCNTs, and the dispersion of Pt nanoparticles (5.22 nm), which significantly increases the electrochemically active surface area (ESCA). In addition, the Pt/CNTs-N-S sensor also exhibits excellent stability and anti-interference performance. Overall, this study provides a simple and practical strategy for the potential application of Pt-based sensors in the detection of DA. Full article

A synergistic and magnetically recoverable NiFe₂O₄–MWCNT–CA nanocomposite was developed for efficient UV-driven photodegradation of hazardous organic pollutants. Biogenic NiFe₂O₄ nanoparticles synthesized using Costus speciosus extract exhibited a crystallite size of 32.5 nm, which increased to 83.6 nm upon incorporation into the MWCNT–cellulose acetate matrix. XRD confirmed the preservation of the cubic spinel structure, while VSM analysis showed maintained ferrimagnetic behavior with a saturation magnetization of 9.64 emu/g, enabling rapid magnetic separation. Although BET analysis revealed a reduction in surface area from 112.46 to 30.99 m²/g due to hybridization, the conductive MWCNT network significantly enhanced charge separation and interfacial electron transport. The composite displayed a widened optical bandgap of 5.3 eV, necessitating UV excitation for photocatalytic activity. Under UV irradiation, it achieved rapid degradation of methylene blue (97%) and Congo red (91%) at 20 mg/L, with corresponding rate constants of 0.119 and 0.076 min⁻¹. Scavenger experiments confirmed hydroxyl radicals (•OH) as the dominant reactive species, followed by photogenerated holes (h⁺). These results demonstrate a robust and synergistically engineered photocatalyst with high efficiency in removing organic pollutants under UV illumination. Full article

Polyethylene glycols (PEGs) are emerging as superior and accessible phase change materials and heat transfer fluids, offering improved thermal properties over conventional thermal oils to meet the demand for innovative, sustainable energy solutions. While general research on PEG performance is still scarce, this paper contributes relevant experimental data. As part of a broad investigation into PEG and PEG-based nanocolloids, this experiment helps to clarify the true potential of these new fluids by outlining both their key advantages and their operational limitations. Consequently, PEG 200 and two PEG 200 + PEG 400 mixtures were considered as base fluids for manufacturing MWCNT nanocolloids, resulting in 15 samples that were thoroughly investigated in terms of density, viscosity and isobaric heat capacity variation with both nanoparticle concentration and temperature. Results revealed that nanocolloid density follows the basic rules for nanoparticle-enhanced fluids, with moderate increase with nanoparticle addition and temperature. Viscosity increased with MWCNT concentration and decreased with temperature, while isobaric heat capacity upsurges with nanoparticle addition. These findings are critical, as they can shed some light into the practical benefits, while clearly explaining the potential drawbacks, of employing these novel fluids in heat transfer applications. Full article

A hybrid material based on the copolymerization of EDOT (3,4-ethylenedioxythiophene) and Py (pyrrole), 1:1 monomer ratio, onto multi-walled carbon nanotubes (MWCNTs) was synthesized through a multistep functionalization approach. The resulting P(EDOT-co-Py)@MWCNT hybrid, poly(3,4-ethylenedioxythiophene-co-pyrrol)@MWCNT hybrid, was characterized by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). These characterizations confirmed the successive functionalization steps, the effective anchoring of the monomers, and the subsequent formation of the copolymer. Transmission electron microscopy (TEM) images revealed a homogeneous polymer coating along the nanotube surface while preserving the structural integrity of the MWCNTs throughout the functionalization and polymerization processes. The P(EDOT-co-Py)@MWCNT hybrid was evaluated as an active electrode material for aluminum-ion storage in an aqueous aluminum sulfate electrolyte. The system exhibited two distinct charge-storage mechanisms: at high current densities, proton surface adsorption dominated, whereas at lower rates, a faradaic contribution associated with polymer chain redox activity and the reversible extraction/insertion of Al³⁺ became prevalent. The hybrid electrode delivered high specific capacities, reaching 200.6, 106.3, and 44.3 mAh g⁻¹ at 0.10, 0.25, and 0.50 A g⁻¹, respectively. These values are comparable to—or even exceed—those reported for similar cathodic materials designed for Al³⁺ storage, highlighting P(EDOT-co-Py)@MWCNT hybrid as a highly promising cathode candidate for aqueous aluminum-ion energy-storage systems. Full article

The flexible foam piezoresistive sensor demonstrates significant potential for wearable strain-sensing applications due to its substantial deformation capacity, excellent flexibility, and cost effectiveness. However, conventional flexible foam piezoresistive sensors often struggle to simultaneously achieve high sensitivity, a wide pressure detection range, fast response and long-term stability. This paper employed a glucose-based sugar-templating method to fabricate a fine-pore (50 μm) foam structure complemented by a dual-filler strategy to enhance overall performance. A robust porous conductive network was constructed by embedding zinc oxide (ZnO) and multi-walled carbon nanotubes (MWCNTs) into a polydimethylsiloxane (PDMS) matrix. The resulting sensor exhibits outstanding piezoresistive properties, featuring a wide linear detection range (0–80% strain) and a high sensitivity of 9.02 kPa⁻¹ within the 0–10 kPa pressure range. It demonstrates rapid response/recovery times of 50/70 ms and maintains stable output performance even after 5000 compression cycles at 300 kPa. The sensor also exhibits negligible environmental interference and excellent long-term stability. When attached to finger joints, feet soles, or the throat, the sensor enables functions such as finger bending recognition, race-walking violation discrimination, gait analysis, and vocal fold vibration recognition, thereby demonstrating its considerable potential for application in human–computer interaction and human motion detection. Full article

To ensure the viability of polymer materials, given the properties and limitations of polymers, hybrid materials have been developed that blend the features of all included components. Researchers have not explored the impacts of the length aspect ratio of nanofillers on the mechanical properties of hybrids in great detail previously. Multi-walled carbon nanotubes are a valuable option because they exhibit improved mechanical properties. Using numerical simulation, the impacts of nanofiller content and the size aspect ratio on two base materials—polyamide 6, polyoxymethylene—and their blends, were determined as a function of the volume ratio, the MWCNTs aspect ratio and the base material blend composition. Numerical analysis employed the ANSYS Material Designer. Random samples of chopped-fibre representative volume elements were generated, meshed and analysed by finite element analysis to obtain the Young’s modulus and Poisson’s ratio for each sample. The results showed a generally linear dependence. Rises in both aspect ratio and volume fraction of MWCNTs increased the Young’s modulus up to 46% and decreased the Poisson’s ratio up to 1.6%. The findings suggest that although the impact of the aspect ratio is not as large as that of the volume ratio, longer MWCNTs are preferable. Full article

A capacitor modeled as a parallel combination of a resistance ($\mathrm{R}$) and a capacitance ($\mathrm{C}$) exhibits three distinct operating regimes when both parameters depend on the applied voltage (V): a positive-capacitance regime ($\mathrm{d}\mathrm{R}/\mathrm{R}>\mathrm{d}\mathrm{V}/\mathrm{V}$), an Ohmic regime ($\mathrm{d}\mathrm{R}/\mathrm{R}=\mathrm{d}\mathrm{V}/\mathrm{V}$), and a negative-capacitance regime ($\mathrm{d}\mathrm{R}/\mathrm{R}<\mathrm{d}\mathrm{V}/\mathrm{V}$). In the limit ($\mathrm{R}\to \mathrm{\infty }$), the device behaves as a conventional permittivity-based capacitor, whereas in the limit ($\mathrm{R}\to 0$), negative capacitance emerges due to nonlinear current–voltage characteristics. To verify this mechanism, we fabricated nanometer-spaced two-electrode structures using multi-walled carbon nanotubes (MWCNTs) and Si crystals. The measurements confirmed negative capacitance consistent with theoretical predictions. Unlike ferroelectric negative capacitance, the effect demonstrated here arises solely from the nonlinear I–V characteristics at the electrode interfaces, without involving any ferroelectric polarization dynamics. This negative capacitance can be interpreted as an equivalent inductance, enabling a two-dimensional tunable reactance element (TDTRE) that operates without electromagnetic coupling and is compatible with conventional IC technologies. Full article