Search Results (95)

The contamination of aquatic systems by industrial dyes, particularly methylene blue (MB), presents a significant environmental challenge due to their chemical stability and toxicity. In this study, the development and application of a novel magnetic nanohybrid comprising multiwall carbon nanotubes (MWCNTs) functionalized with maghemite (γ-Fe₂O₃) nanoparticles biosynthesized using Eucalyptus globulus extract (denoted MWNT-NPE) is reported. The material was thoroughly characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Vibrating Sample Magnetometer (VSM), and Fourier-Transform Infrared (FTIR) techniques, revealing high crystallinity, mesoporosity, and superparamagnetic behavior. The MWNT-NPE exhibited exceptional MB adsorption performance under optimized conditions (pH 6, 0.8 g L⁻¹ dose, 40 min equilibrium), achieving a maximum adsorption capacity of 92.9 mg g⁻¹. Kinetic analysis indicated chemisorption and physisorption regimes depending on MB concentration, with the pseudo-second-order and Freundlich isotherm models providing the best fits of experimental data. FTIR spectroscopy demonstrated that the removal mechanism involves π–π stacking, hydrogen bonding, and electrostatic interactions between MB molecules and the composite’s surface functional groups. Notably, the magnetic nanohybrid retained over 98% removal efficiency across five regeneration cycles and successfully removed MB from synthetic effluents with efficiencies exceeding 91%. These findings highlight the synergistic adsorption and magnetic recovery capabilities of the bio-functionalized hybrid system, presenting a sustainable, reusable, and scalable solution for industrial dye remediation. Full article

To develop antistatic materials suitable for semiconductor wafer transportation trays, in situ polymerized polystyrene (PS) and polyester (PETE) materials incorporating multi-walled carbon nanotubes (MWNTs) were synthesized. Their thermal and electrical properties were evaluated under conditions relevant to semiconductor tray manufacturing. Both the PS and PETE materials exhibited improved thermal stability with an increasing MWNT content. Differential scanning calorimetry (DSC) revealed that the glass transition temperature (T_g) of the PS increased from 82 °C (0 wt%) to 86 °C (1.0 wt%) and 91 °C (2.0 wt%), while that of the PETE increased from 83 °C to 84 °C and 90 °C, respectively. Surface resistivity measurements also demonstrated enhanced electrical conductivity. For the PS, resistivity decreased from >10¹³ Ohm/sq to 8.8 × 10³ and 3.7 × 10³ Ohm/sq at 1.0 wt% and 2.0 wt% MWNT, respectively. The PETE materials followed a similar trend, with values dropping from >10¹³ Ohm/sq to 5.9 × 10³ and 0.2 × 10³ Ohm/sq. These results confirm that MWNT incorporation effectively enhances both thermal and electrical performance, demonstrating the potential of MWNT/PS and MWNT/PETE as antistatic materials for semiconductor applications. Full article

Experimental investigations of the diode-laser-induced ignition of potassium picrate (KP) with a multi-walled carbon nanotube (MWNT) additive are presented in this article. KP/MWNT composites with varying contents were prepared directly by adding different quantities of MWNTs to a KP solution after the last synthesis step. Due to capillary action, the MWNTs homogeneously coated the surface of the KP, and some KP crystallized inside the MWNTs. The samples were characterized by scanning and transmission electron microscopy, differential thermal analysis, and laser ignition tests. At a constant laser power density, the doped KP showed a much shorter ignition delay time than the undoped KP (from 28.8 ms to 4.5 ms). Therefore, the higher the dopant MWNT ratio is, the shorter the ignition delay time is. Additionally, the more MWNTs are used to dope KP, the lower the required ignition power is. Full article

Silver nanoparticle-coated multi-walled carbon nanotube (Ag/MWNT) composites were prepared using a chemical plating method that effectively controls the overgrowth of silver nanoparticles, ensuring uniform particle size. Functionalization of the carbon nanotube surface with numerous functional groups facilitates the binding of silver ions to multi-walled carbon nanotubes (MWNTs). This process results in Ag/MWNT composites with a uniform distribution of silver nanoparticles, prepared through reduction via the silver mirror reaction. The impact of dispersants and reducing agents on the silver coating of carbon nanotubes was studied. The results revealed the formation of negatively charged functional groups (-COOH, -OH, -C=O, and -NH2) on the nanotube surface. These groups acted as nucleation sites for the formation of silver nanoparticles. These groups acted as nucleation sites for the formation of silver nanoparticles. Simultaneously, the Ag/MWNT composites demonstrated effective dispersion within the matrix, improving the electrical conductivity of the electronic paste by 32.1% and 33.1%. This improvement was attributed to the forming of a conductive pathway within the silver-modified composite. Ag/MWNT composites within the paste system improved interfacial contact between fillers and the matrix, enhancing their potential applications in thermal interface materials. Full article

In this manuscript, we are reporting on the influence of MWNTs (multiwalled carbon nanotubes) on the structural, bonding, and surface morphological response on sulfur nanoparticles. Sulfur and multiwalled carbon nanotube (MWCNT) composites are formed using the solution casting method. The concentration of MWCNTs (0.01 and 0.05) and sulfur (0.99 and 0.95), respectively, was taken in weight ratios during fabrication of the composites. These fabricated composites have been characterized using XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy), and FTIR (Fourier-transform infrared spectroscopy) techniques. XRD spectra reveal that the crystallite size distribution was in the range of ca. 55 nm to 78 nm, as well as enhanced crystallinity upon increasing the concentration of MWCNTs in sulfur composites. Dislocation density and strain have been found to be increased in composites showing increased augmentation of MWCNTs (i.e., S95% MWCNT5%), while FESEM images confirm the uniform distribution of MWCNTs in sulfur composites, along with round structures at the nanoscale range. FTIR spectra depicted the bending and stretching of C-H bands. Composites with a higher concentration of MWCNTs show slightly more stretching vibrations. This indicates the further delocalization of electrons, which reveals that as MWCNTs’ concentration is increased, electrical conductivity enhances, showing that MWCNTs could perform better in electrical industries. The further delocalization of electrons also expresses that free electron–hole pair formation is better in composites with a higher concentration of MWCNTs, accounting for the fact that the photocatalytic response may increase in composites with a higher concentration of MWCNTs. Overall, it can be said that as the MWCNT concentration is ameliorated, the composites show a more crystallized structure with more vibrations. This characteristic of MWCNTs/sulfur composites is useful in photocatalytic response as well as in cathode materials in sulfur batteries. Full article

To evaluate lung toxicity due to inhalation of multi-walled carbon nanotubes (MWCNTs) in rats, we developed a unique MWCNT aerosol generator based on dry aerosolization using the aerodynamic cyclone principle. Rats were exposed to MWNT-7 (also known as Mutsui-7 and MWCNT-7) aerosolized using this device. We report here an analysis of previously published data and additional unpublished data obtained in 1-day, 2-week, 13-week, and 2-year inhalation exposure studies. In one-day studies, it was found that approximately 50% of the deposited MWNT-7 fibers were cleared the day after the end of exposure, but that clearance of the remaining fibers was markedly reduced. This is in agreement with the premise that the rapidly cleared fibers were deposited in the ciliated airways while the slowly cleared fibers were deposited beyond the ciliated airways in the respiratory zone. Macrophage clearance of MWNT-7 fibers from the alveoli was limited. Instead of macrophage clearance from the alveoli, containment of MWNT-7 fibers within induced granulomatous lesions was observed. The earliest changes indicative of pulmonary toxicity were seen in the bronchoalveolar lavage fluid. Macrophage-associated inflammation persisted from the one-day exposure to MWNT-7 to the end of the two-year exposure period. Correlation of lung tumor development with MWNT-7 lung burden required incorporating the concept of area under the curve for the duration of the study; the development of lung tumors induced by MWNT-7 correlated with lung burden and the duration of MWNT-7 residence in the lung. Full article

Despite intensive toxicological studies of carbon nanotubes (CNTs) over the last two decades, only a few studies have demonstrated their pulmonary carcinogenicities in chronic animal experiments, and the underlying molecular mechanisms are still unclear. To obtain molecular insights into CNT-induced lung carcinogenicity, we performed a transcriptomic analysis using a set of lung tissues collected from rats in a 2-year study, in which lung tumors were induced by repeated intratracheal instillations of a multiwalled carbon nanotube, MWNT-7. The RNA-seq-based transcriptome identified a large number of significantly differentially expressed genes at Year 0.5, Year 1, and Year 2. Ingenuity Pathway Analysis revealed that macrophage-elicited signaling pathways such as phagocytosis, acute phase response, and Toll-like receptor signaling were activated throughout the experimental period. At Year 2, cancer-related pathways including ERBB signaling and some axonal guidance signaling pathways such as EphB4 signaling were perturbed. qRT-PCR and immunohistochemistry indicated that several key molecules such as Osteopontin/Spp1, Hmox1, Mmp12, and ERBB2 were markedly altered and/or localized in the preneoplastic lesions, suggesting their participation in the induction of lung cancer. Our findings support a scenario of inflammation-induced carcinogenesis and contribute to a better understanding of the molecular mechanism of MWCNT carcinogenicity. Full article

In order to achieve simple, rapid, and highly sensitive detection of trimethoprim (TMP), a magnetic molecularly imprinted carbon paste electrode (MCPE) was prepared by drop-coating magnetic molecularly imprinted polymer (MIP@Fe₃O₄@MWNTs) on the surface of reduction graphene oxide (rGO)/MCPE doped with Fe₃O₄@MWNTs. The introduction of multi-walled carbon nanotubes (MWNTs) and rGO served as dual signal-amplification materials, which can improve the response sensitivity of the sensor. In addition, the magnetic interaction between the substrate electrode and the molecularly imprinted material was beneficial to increasing the stability of the sensor. As expected, the electrochemical sensor not only showed sensitivity and selectivity for the detection of TMP, but it also possessed good stability. The detection range for TMP was 4.0 × 10⁻⁹~5.0 × 10⁻⁴ mol/L, and the detection limit was 1.2 × 10⁻⁹ mol/L. The response performance varied within 10% when the sensor was placed for more than 2 months and used more than 60 times. The spiked recoveries of TMP in environmental water samples, urine samples, and pharmaceuticals (drugs) were between 91% and 110%, and the relative standard deviation (RSD) was within 5%. Full article

Hydrodeoxygenation (HDO) is one of the most promising approaches to upgrading pyrolysis oils, but this process normally operates over expensive noble metal catalysts (e.g., Ru/C, Pt/Al₂O₃) under high-pressure hydrogen gas, which raises processing costs and safety concerns. In this study, a wood-derived pyrolysis oil was upgraded in supercritical ethanol using formic acid as an in situ hydrogen source at 300 °C and 350 °C, over a series of nickel–molybdenum-tungsten (NiMoW) catalysts supported on different materials, including Al₂O₃, activated carbon, sawdust carbon, and multiwalled nanotubes (MWNTs). The upgrading was also conducted under hydrogen gas (an ex situ hydrogen source) for comparison. The upgrading process was evaluated by oil yield, degree of deoxygenation (DOD), and oil qualities. The NiMoW/MWNT catalyst showed the best HDO performance among all the catalysts tested at 350 °C, with 74.8% and 70.9% of oxygen in the raw pyrolysis oil removed under in situ and ex situ hydrogen source conditions, respectively, which is likely owing to the large pore size and volume of the MWNT support material, while the in situ hydrogen source outperformed the ex situ hydrogen source in terms of upgraded oil yields and qualities, regardless of the catalysts employed. Full article

In this paper, the relative humidity sensor properties of graphene oxide (GO) and graphene oxide/multiwalled nanotubes (GO/MWNTs) composites have been investigated. Composite sensors were fabricated by direct laser scribing and characterized using UV-vis-NIR, Raman, Fourier transform infrared, and X-ray photoemission spectroscopies, electron scanning microscopy coupled with energy-dispersive X-ray analysis, and impedance spectroscopy (IS). These methods confirm the composite homogeneity and laser reduction of GO/MWNT with dominant GO characteristics, while ISresults analysis reveals the circuit model for rGO-GO-rGO structure and the effect of MWNT on the sensor properties. Although direct laser scribing of GO-based humidity sensor shows an outstanding response (|ΔZ|/|Z| up to 638,800%), a lack of stability and repeatability has been observed. GO/MWNT-based humidity sensors are more conductive than GO sensors and relatively less sensitive (|ΔZ|/|Z| = 163,000%). However, they are more stable in harsh humid conditions, repeatable, and reproducible even after several years of shelf-life. In addition, they have fast response/recovery times of 10.7 s and 9.3 s and an ultra-fast response time of 61 ms when abrupt humidification/dehumidification is applied by respiration. All carbon-based sensors’ overall properties confirm the advantage of introducing the GO/MWNT hybrid and laser direct writing to produce stable structures and sensors. Full article

The increasing resistance of bacteria and fungi to antibiotics is one of the health threats facing humanity. Of great importance is the development of new antibacterial agents or alternative approaches to reduce bacterial resistance to available antibacterial drugs. Due to the complexity of their properties, carbon nanomaterials (CNMs) may be of interest for a number of biomedical applications. One of the problems in studying the action of CNMs on microorganisms is the lack of universally standardized methods and criteria for assessing antibacterial and antifungal activity. In this work, using a unified methodology, a comparative study of the antimicrobial properties of the CNM systemic kit against common opportunistic microorganisms, namely Escherichia coli and Staphylococcus aureus, was carried out. Multiwalled carbon nanotubes (MWNTs), catalytic filamentous carbon with different orientations of graphene blocks (coaxial–conical and stacked, CFC), ionic carbon (OLC), and ultrafine explosive nanodiamonds (NDs) were used as a system set of CNMs. The highest antimicrobial activity was shown by NDs, both types of CFCs, and carboxylated hydrophilic MWCNTs. The SEM results point out the difference between the mechanisms of action of UDD and CFC nanotubes. Full article

One-dimensional multi-walled carbon nanotubes (MWNTs) have unique electrical properties, but they are not solution-processable, which severely limits their applications in microelectronic devices. Therefore, it is of great significance to improve the solubility of MWNTs and endow them with new functions by chemical modification. In this work, MWNTs were in situ functionalized with poly[(1,4-diethynyl-benzene)-alt-(3-hexylthiophene)] (PDHT) via Sonogashira–Hagihara polymerization. The obtained material PDHT-g-MWNTs was soluble in conventional organic solvents. By sandwiching a PDHT-g-MWNTs film between Al and ITO electrodes, the fabricated Al/PDHT-g-MWNTs/ITO electronic device exhibited nonvolatile rewritable memory behavior, with highly symmetrical turn-on/off voltages, a retention time of over 10⁴ s, and durability for 200 switching cycles. These findings provide important insights into the development of carbon nanotube-based materials for information storage. Full article

In this work, the high yield of MWNTs was prepared by chemical vapor deposition (CVD) method, followed by annealing at 2000–2800 °C, and the effects of high annealing temperature on metal impurities and defects in multi-walled carbon nanotubes (MWNTs) was explored. Furthermore, the annealed MWNTs were dispersed using a sand mill to make a conductive slurry, and finally the cathode LiNi_0.5Co_0.2Mn_0.3O₂ was added to the assembled batteries, and the application of MWNTs (slurry) as conductive agents in LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) cathode materials by sand-mill dispersion on the performance of lithium-ion batteries was investigated. The results indicate that high temperature annealing can effectively remove the residual metal impurities from MWNTs and the defects in MWNTs gradually decreases as the temperature rises. In addition, 2 wt% of MWNTs (slurry) in LiNi_0.5Co_0.2Mn_0.3O₂ is sufficient to form an electronically conductive network; as a result, the electronic conductivity and the high rates performance of the LiNi_0.5Co_0.2Mn_0.3O₂ batteries were greatly improved. The LiNi_0.5Co_0.2Mn_0.3O₂ battery with MWNTs slurries annealed at 2200 ℃ as a conductive additive displays the highest initial discharge capacity of 173.16 mAh·g⁻¹ at 0.1 C. In addition, after 100 cycles, a capacity retention of 95.8% at 0.5 C and a discharge capacity of 121.75 mAh·g⁻¹ at 5 C were observed. The multi-walled carbon nanotubes used as conductive agents in LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) cathode materials show excellent battery behaviors, which would provide a new insight for the development of high-performance novel conductive agents in lithium-ion batteries. Full article

The addition of nanoparticles as fillers has a significant influence in modifying the dynamic conditions and avoiding crystallization in polymer composites. In this work, (PEO)₄CF₃COOLi electrolyte and multi-walled carbon nanotubes (MWCNTs) were used to prepare composites by a solution method. The formation of the new composite was evidenced by the experimental results obtained from DSC analysis and infrared spectroscopy (FTIR). The impedance spectroscopy analysis shows a notable decrease in the resistance, which is attributed to an interaction between the oxygen of the polymer and the Li⁺ cations of the salt, and the interactions between the electrolyte and the MWNTs. Values of dc conductivity of 8.42 × 10⁻⁴ S cm⁻¹ at room temperature are obtained at a concentration of 2.0 wt.% MWCNT in the whole electrolyte. The results indicate that membranes can be used in technological devices such as batteries and gas or moisture sensors. Full article

Carbon nanotubes (CNTs) are thought to have higher elastic modulus and strength than carbon fibers. The recent development of spinnable multi-walled carbon nanotubes (MWNTs) enables us to produce unidirectional MWNT reinforced polymer-based composites with a higher volume fraction of CNTs. The results of tensile tests of spinnable MWNTs in scanning electron microscopes show, however, that Young’s modulus and tensile strength of MWNTs are not as high as expected. Annealing and developing thinner spinnable MWNTs will be the solution to improving the tensile property. In this study, as-produced and annealed untwisted yarns composed of MWNTs with three different diameters were prepared, and the tensile properties of spinnable MWNTs were estimated from the tensile properties of the untwisted yarns to investigate the effect of annealing and diameter on the overall tensile property of MWNTs. Furthermore, tensile tests of unidirectional MWNT reinforced epoxy composites were conducted and the contribution of the tensile property of MWNTs to the bulk tensile property of the composite was discussed. As a result, it was found that MWNTs with thinner diameters had higher Young’s modulus and tensile strength and annealing improved Young’s modulus of MWNTs, in addition to that the bulk tensile property of unidirectional MWNT reinforced epoxy composites was primarily determined by the tensile property of MWNTs. The results support previous findings from a limited number of tensile tests in SEM/TEM, and also reveal the validity of estimating the tensile properties of individual CNTs by tensile testing of untwisted yarns. In addition, the discussion on composite materials suggests that the tensile property of composite materials can be enhanced by improving the tensile property of MWNTs. Full article