Performance Of Multiwalled Carbon Nanotubes Research Articles

Investigation on open water adsorption performance of multi-walled carbon nanotubes modified MIL-96(Al)

An aluminum-based metal-organic framework material MIL-96(Al) was prepared by solvent-thermal synthesis method, and by adding multi-walled carbon nanotubes (MWCNTs) in the preparation process, MWCNT/MIL-96(Al) composite adsorbent was synthesized for the first time. The morphology of the adsorbents was discussed by scanning electron microscopy (SEM). In adsorption experiments under different working conditions, MIL-96(Al) exhibited a stable equilibrium adsorption capacity, while the addition of only 0.50% mass fraction of multi-walled carbon nanotubes increased equilibrium adsorption capacity by approximately 30%. The enhancement ratio of six composite adsorbents compared to MIL-96(Al) in equilibrium adsorption capacities was almost constant under different working conditions. The adsorption rate of MIL-96(Al) could reach up to 0.573 g g−1 h, while that of the composite adsorbents under the same conditions was 0.763 g g−1 h. MIL-96(Al) could be completely desorbed within 40 min at 110 °C, and the optimal desorption temperature of MWCNT/MIL-96(Al) was reduced to 100 °C. The cyclic stability of the seven adsorbents was also confirmed through cyclic regeneration experiments. The experimental results indicated that the MWCNT/MIL-96(Al) composite adsorbent was a potential adsorbent for solar-driven atmospheric water harvesting in arid regions.

High thermoelectric performance of multiwalled carbon nanotubes based ionogels

Ionogels have emerged as promising thermoelectric materials with Seebeck coefficient 2–3 orders of magnitude higher than Seebeck coefficient of their inorganic counter parts. However, they suffer from the problem of low ionic conductivity, which can be improved with the addition of inorganic nanofillers to the ionogels. In the present work, thermoelectric performance of multiwall carbon nanotubes (MWCNTs) based ionogels (IGs) has been investigated. IGs were synthesized via in situ radical polymerization of polyethylene glycol 200 dimethacrylate (PEG200DMA) difunctional monomer in the presence of 1-butyl-3-methyl imidazolium tetrafluoroborate (an ionic liquid) and MWCNTs. Three composites namely MWCNTs-0.25, MWCNTs-0.5 and MWCNTs-1 were prepared having the concentration of MWCNTs by 0.25, 0.5 and 1 wt% respectively. A remarkable 75.3% enhancement in ionic conductivity was achieved for the MWCNTs-1 wt% ionogel compared to the base IG at 40 °C. This substantial improvement can be attributed to the "breathing polymer chain model," which describes the dissociation of ion aggregates due to the interaction between the ionic liquid and polymer chains. In terms of thermoelectric performance amongst the MWCNT ionogels, 0.25 wt% MWCNT-based ionogels was the optimized concentration with very high Seebeck coefficient of 1.70 mV/K and power factor of 4.1 µW/m. K along with excellent thermal stability up to 386 °C. These high-performing ionogels hold great promise for efficient utilization of low-grade thermal energy.

Improved electrochemical performance of multi-walled carbon nanotube reinforced gelatin biopolymer for transient energy storage applications.

Multi-walled carbon nanotube (MWCNT) incorporated biodegradable gelatin nanocomposites (Gel/MWCNT) have been prepared following a facile solution processing method. The Fourier-transform infrared (FTIR) spectroscopy, field emission scanning electronic microscopy (FESEM), and water contact angle (WCA) measurements revealed improved structural properties and surface morphological features of the nanocomposite films due to the incorporation of MWCNT. A four-fold decrease in the DC resistivity was obtained due to the addition of MWCNTs. The specific capacitance of the nanocomposite increased from 0.12 F/g to 12.7 F/g at a current density of 0.3 μA/cm2 due to the incorporation of 0.05 wt.% MWCNT. EIS analysis and the corresponding Nyquist plots demonstrated the contributions of the different electrical components responsible for the improved electrochemical performance were evaluated using an equivalent AC circuit. The incorporation of MWCNTs was found to reduce the charge-transfer resistance from 127 Ω to 75 Ω and increase the double-layer capacitance from 4 nF to 9 nF. The Gel/MWCNT nanocomposite demonstrated improved cyclic stability with a retention of 95% of the initial capacitance even after 5000 charging/discharging cycles. The biodegradability test showed that the nanocomposite degraded completely after 30 hours of immersion in water. This fully biocompatible nature of the nanocomposites with high specific capacitance and low charge transfer resistance may offer a promising route to fabricate a nature-friendly electrode material for energy storage applications.

Experimental thermal performance investigation of double pipe heat exchanger using MWCNT/water nanofluid

This paper presents an experimental study investigating the thermal performance of multiwall carbon nanotubes in a twin-pipe heat exchanger using a water-based fluid. The research followed a two-step method, where a concentration of 0.01 weight percent of SDS surfactant was utilized to prepare the carbon nanotubes. The heat transfer coefficient, friction coefficient, and overall heat transfer coefficient of the nanofluid were compared to those of the base fluid. The results revealed that the addition of a small amount of multiwall carbon nanotubes significantly enhanced the thermal conductivity and heat transfer coefficient of the water-based fluid. Moreover, the heat transfer coefficient exhibited an increase with higher Reynolds numbers. When the nanofluid flowed counter currently and was in the outer tube, the highest values for the overall heat transfer coefficient and the heat transfer coefficient were determined as 2864 and 7655.7 W/m2K, respectively. The findings indicate notable improvements in the thermophysical and thermal characteristics of the nanofluid.

Wear Performance of Multi-Walled Carbon Nanotubes Grafted Hybrid Fiber (Carbon–Aramid) Friction Materials

Wear Performance of Multi-Walled Carbon Nanotubes Grafted Hybrid Fiber (Carbon–Aramid) Friction Materials

Durability performance of multi-walled carbon nanotube reinforced ordinary Portland/calcium sulfoaluminate cement composites to sulfuric acid attack at early stage

Exposure of cement-based structures to sulfuric acid environments can cause significant degradation. Therefore, this study focuses on the effect of multi-walled carbon nanotubes (MWCNTs) on the sulfuric acid resistance of ordinary Portland cement (OPC)-sulfoaluminate cement (SAC) composites (as repair material) at early stage. Samples were exposed to three concentrations of acid solution for 60 days. The degradation kinetics, chemistry, and microstructures of the composites were analyzed. The results of degradation kinetics (dimensional change, mass and strength loss) showed that the MWCNTs modified composites had a lower degradation rate compared to the composites without MWCNTs. XRD, TG, X-CT and SEM analysis showed that MWCNTs promoted hydration, improved structure compactness, interrupted the generation and propagation of microcracks through the bridge effect, and formed protective barriers. The degradation rate of the composite was reduced by the double optimization of chemistry and microstructure. However, diffusion-dissolution-precipitation is still the main mode of degradation in composites subjected to sulfuric acid attack, regardless of MWCNT content mixed into the composite system.

Annealing effect on the thermoelectric properties of multiwall carbon nanotubes

In this article, it is demonstrated that transport properties and thus thermoelectric performance of multiwall carbon nanotubes (MWCNTs) can be enhanced significantly by annealing. Two different samples of MWCNTs with small and large diameters were investigated. The as-prepared MWCNT samples were treated at different conditions of annealing. The pristine and annealed MWCNTs were investigated using x-ray diffraction, Raman spectroscopy and scanning electron microscope in order to investigate the microstructure, defect content and morphology before and after the annealing process. The electrical conductivity, Seebeck coefficient and thermal conductivity were measured over the temperature range of (300–450 K) and were found to correlate with the tube diameter and the annealing conditions. The electrical conductivity and Seebeck coefficient measurements show that the conduction mechanism in MWCNTs is thermal activation as the samples have degenerate semiconductor-like behavior. Upon annealing, the Seebeck coefficient increases, followed by a reduction in the thermal conductivity. The thermoelectric power factor was enhanced by annealing to realize the highest value of 1.06 μW m −1 K −2 at 475 K for the sample with the larger diameter. The thermoelectric figure of merit ZT was calculated to determine the performance of the materials. ZT of the sample of the larger tube's diameter was enhanced by about 247% at 450 K. • Pristine and annealed MWCNTs were investigated using x-ray diffraction, Raman spectroscopy and scanning electron microscope. • Thermoelectric performance of multiwall carbon nanotubes (MWNTs) is significantly enhanced by annealing. • The thermoelectric figure of merit ZT was enhanced by about 247% at 450 K.

Multi-walled carbon nanotubes derived graphene nanoribbons for high performance supercapacitor applications

This study delineates the supercapacitive performance of multi-walled carbon nanotubes derived nanoribbons. Acid-processed carbon nanotubes were exfoliated and reduced with microwaves to yield high quality graphene nanoribbons (GNRs). Morphological and spectroscopic investigations revealed the successful preparation of graphene nanoribbons from carbon nanotubes. The three electrode system configuration with microwave exfoliated graphene nanoribbons (MWGNRs) based working electrode and H2SO4-PVA gel electrolyte has shown high specific capacitance of 404 F/g at 2 mVs−1 scan rate. This three electrode configuration showed 97.3% of initial capacitance retention after 10,000 cycles, which proves good cycle stability and retention capability of the MWGNRs based electrode with gel electrolyte. A supercapacitive device with MWGNRs based electrodes and 1 M H2SO4 –PVA gel electrolyte was fabricated and tested, which also showed high supercapacitive performance. MWGNRs have more number of reactive edges and high specific surface area as compared to pristine carbon nanotubes and therefore exhibit high specific capacitance. The proposed method is highly scalable and can pave a way to develop high performance low cost supercapacitors.

Effects of modification groups and defects on the desalination performance of multi-walled carbon nanotube (MWNT) membranes

Like single-wall carbon nanotubes (SWNTs), multi-wall carbon nanotubes (MWNTs) have channels for selective separation of ions. Moreover, MWNTs have the advantages of simpler preparation and lower cost, potentially allowing wider applications in the desalination industry. In this study, the transport of water and ions inside two types of MWNTs, i.e., double-wall carbon nanotubes (DWNTs) and tri-wall carbon nanotubes (TWNTs) were investigated using non-equilibrium molecular dynamics simulations. Modification groups, including carbon chains of different lengths and types with hydrophilic groups like carboxylate anion (COO–), and ammonium (NH3+), were used to improve the salt rejection performance. The simulation results suggest that 100% salt rejection could be achieved by adding different modification groups to various MWNTs ranging from 13 to 20 Å. More importantly, this study demonstrates that MWNT membranes with 100% desalination have water fluxes that are 10–30% greater than that of SWNT membranes with 100% desalination, implying the greater potential of MWNTs as building blocks towards next-generation desalination membranes. Additionally, even though all real-world carbon nanotubes (CNTs) have a certain amount of defects from the production process, most previous molecular model studies of water and ions transport in CNTs assumed that CNTs were perfect and defect-free. This study shows for the first time that CNTs with defects have improved salt rejection rates than perfect carbon nanotubes, although the former have lower water fluxes than the latter.

Performance of multiwalled carbon nanotube doped fly ash based clay bricks

Performance of multiwalled carbon nanotube doped fly ash based clay bricks

Application of MnO2/MWCNT composite in supercapacitors

Supercapacitors have attracted tremendous attention due to high power density, high rate capability, long cycling life and safety. The article presents the comparison of electrochemical performance of multi-walled carbon nanotubes (MWCNTs), MnO2 and MnO2/MWCNT nanocomposite as electrode mass in supercapacitor. Materialswere characterized by X-ray diffraction, scanning electron microscopy, low temperature nitrogen adsorption and cyclic voltammetry. The specific capacitance was found to increase in the row MWCNTs < MnO2 < MnO2/MWCNT achieving 32, 90 and 140 F · g−1 at 5 mV · s−1, respectively. The outstanding improvement of specific capacitance for MnO2/MWCNT was attributed to the combination of high electrical conductivity of carbon nanotubes enhancing the charge transport and faradic redox reactions occurring on MnO2 surface.

Effects of Modification Groups and Defects on the Desalination Performance of Multi-Walled Carbon Nanotube (Mwnt) Membranes

Effects of Modification Groups and Defects on the Desalination Performance of Multi-Walled Carbon Nanotube (Mwnt) Membranes

Determination of new generation amide insecticide residues in complex matrix agricultural food by ultrahigh performance liquid chromatography tandem mass spectrometry

Eight new generation amide insecticide residues analysis by multiwalled carbon nanotubes (MWCNs) cleanup, combined with QuEChERS and ultrahigh performance liquid chromatography tandem mass spectrometry has been developed and successfully applied in complex matrix such as orange, celery, onion, litchi, mango, shallot, chives, avocado, garlic. The matric effect of MWCNs is optimized and compared with ordinary cleanup materials. The results show that the performance of MWCNs is fine and effectively reduce matrix interference. Through chemical structure skeletons analyzed, chlorantraniliprole, bromoantraniliprole, and cyantraniliprole can cause same product ions of m/z 286.0 or 177.1 in the ESI+ mode, then tetrachlorantraniliprole and cyclaniliprole can produce collective ions of m/z 146.9 in the ESI− mode. The coefficients (R2) were greater than 0.9990, the limit of quantification ranges from 0.03 to 0.80 μg/kg, the recovery rate ranges from 71.2 to 120%, and the relative standard deviation (RSD) ranges from 3.8 to 9.4%. The method is fast, simple, sensitive, and suitable for the rapid determination of amide pesticides in complex matrix agricultural food.

The effect of thickness on the multiwalled carbon nanotubes performance in glass/epoxy composite laminates under dynamic loading

AbstractThe aim of this research is to investigate the thickness influence on the efficiency of multiwalled carbon nanotubes (MWCNTs) in glass/epoxy composite laminates under the high‐velocity impact. Combining 0.25 wt% of MWCNTs in the 4‐layer and 8‐layer specimens and 0.1 wt% of MWCNTs in the 16‐layer specimen led to the maximum rise in the energy absorption and specific perforation energy compared with the unreinforced laminates. The significant growth in energy absorption in the 4‐layer, 8‐layer, and 16‐layer specimens was 5.8, 8.3, and 14.4 J, respectively. The number of agglomerations (dislocations) in the matrix was consequently increased as a function of thickness, which led to the better performance of MWCNTs with lower weight percentages in the composite laminates containing more layers. The scanning electron microscope was used to observe the dispersion and agglomeration of MWCNTs in the resin epoxy, and there was also an improvement in the fiber–resin bonding.

Research on the smart behavior of MCNT grafted CF/cement-based composites

To solve the disadvantages of weak bonding between the carbon fiber (CF) and the cement matrix, as well as the poor dispersion performance of multi-walled carbon nanotubes (MCNT) in cement paste, hydrothermal synthesis and chemical grafting methods were combined to graft MCNT on the surface of CF. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) were coupled used to evaluate the grafting efficiency. Four-electrode method and electrochemical impedance spectroscopy (EIS) were applied to assess the electrical property of MCNT grafted CF/cement-based composites. The smart behavior of MCNT grafted CF/cement-based composites were characterized under monotonic and cyclic loading. Results showed that the hydrothermal synthesis method can effectively graft MCNT on the surface of CF, and the grafting ratio as indicated by nitrogen element was 6.78%. The conductivity of MCNT grafted CF/cement-based composites was far superior to that of untreated CF/cement-based composites. Also, the composite with the addition of MCNT grafted CF was more sensitive to the cyclic stress. Therefore, the stress sensitive property of MCNT grafted CF/cement-based composites was significantly improved, compared to its untreated counterpart.

An in-silico layer-by-layer adsorption study of the interaction between Rebaudioside A and the T1R2 human sweet taste receptor: modelling and biosensing perspectives

The human sweet taste receptor (T1R2) monomer—a member of the G-protein coupled receptor family that detects a wide variety of chemically and structurally diverse sweet tasting molecules, is known to pose a significant threat to human health. Protein that lack crystal structure is a challenge in structure-based protein design. This study focused on the interaction of the T1R2 monomer with rebaudioside A (Reb-A), a steviol glycoside with potential use as a natural sweetener using in-silico and biosensing methods. Herein, homology modelling, docking studies, and molecular dynamics simulations were applied to elucidate the interaction between Reb-A and the T1R2 monomer. In addition, the electrochemical sensing of the immobilised T1R2-Reb-A complex with zinc oxide nanoparticles (ZnONPs) and graphene oxide (GO) were assessed by testing the performance of multiwalled carbon nanotube (MWCNT) as an adsorbent experimentally. Results indicate a strong interaction between Reb-A and the T1R2 receptor, revealing the stabilizing interaction of the amino acids with the Reb-A by hydrogen bonds with the hydroxyl groups of the glucose moieties, along with a significant amount of hydrophobic interactions. Moreover, the presence of the MWCNT as an anchor confirms the adsorption strength of the T1R2-Reb-A complex onto the GO nanocomposite and supported with electrochemical measurements. Overall, this study could serve as a cornerstone in the development of electrochemical immunosensor for the detection of Reb-A, with applications in the food industry.

Optimum Electrical and Dielectric Performance of Multi-Walled Carbon Nanotubes Doped Disposed Transformer Oil

This paper intends to prepare a nanofluid sample by suspending Multi-walled Carbon Nanotubes (MWCNTs) at 0.005g/L concentration and analyze the behavior of electrical and dielectric properties based on the International Electrotechnical Commision test method. In order to validate the effectiveness of MWCNT nanofluid, alternating current breakdown voltage (BDV), negative polarity lightning impulse (LI), dielectric permittivity, dissipation factor (DF), DC resistivity and Raman structural measurement are executed accordingly. In the following, an analysis of the statistical distribution using the two-parameter Weibull distribution law of BDV and LI are evaluated at four experimental conditions to predict the probability of breakdown occurring at different percentages. Based on the observation, the MWCNT filler has a substantial effect in improving the BDV and LI characteristics of disposed mineral oil. The permittivity, DF and resistivity performance of MWCNT nanofluid from 25 °C to 90 °C also produces comparable and reliable performance as a fresh transformer oil. As for Raman structure, the revolution of transformer oil by doping MWCNT does not disrupt the original chemical structure of mineral oil. Hence, this study proves the improvement of the electrical and the behavior of dielectric properties and chemical structure of nanofluid, providing a huge contribution towards the development of insulating materials for transformer application.

Performance of multi-wall carbon nanotubes modified by chitosan and EDTA in the removal of Direct Blue 15 dye from aqueous solutions

Dyes are considered to be important pollutants in different industries (e.g., textile) and contain various organic materials with complicated structures. These compounds are mainly carcinogenic and toxic and less biodegradable when discharged into the environment. The present study aimed to investigate the performance of multi-wall carbon nanotubes (MWCNTs) modified by chitosan and EDTA in the removal of Direct Blue 15 dye from aqueous solutions. MWCNT was synthesized and characterized using the BET, zeta potential, DLS, SEM, and FTIR techniques. The effects of key parameters including pH, adsorbent dose, initial dye concentration, and contact time were also evaluated. The experimental data of the adsorption process were analyzed using the Langmuir and Freundlich models. With the increased contact time, the removal efficiency of the dye improved, while the increased pH, initial dye concentration, and adsorbent dose led to the reduced dye removal efficiency. With the optimum values of pH (=7), contact time (60 min), adsorbent dose (0.5 g/L), and initial dye concentration (60 mg/L), the maximum adsorption capacity was determined to be 114.42 mg/g. According to the results, the adsorption process using the modified MWCNT followed the Langmuir model and pseudo-second-order kinetics.

Comparing the Adsorption Performance of Multiwalled Carbon Nanotubes Oxidized by Varying Degrees for Removal of Low Levels of Copper, Nickel and Chromium(VI) from Aqueous Solutions

Functionalized multiwalled carbon nanotubes (MWCNTs) have drawn wide attention in recent years as novel materials for the removal of heavy metals from the aquatic media. This paper investigates the effect that the functionalization (oxidation) process duration time (3 h or 6 h) has on the ability of MWCNTs to treat water contaminated with low levels of Cu(II), Ni(II) and Cr(VI) (initial concentrations 0.5–5 mg L−1) and elucidates the adsorption mechanisms involved. Adsorbent characterization showed that the molar ratio of C and O in these materials was slightly lower for the oxMWCNT6h, due to the higher degree of oxidation, but the specific surface areas and mesopore volumes of these materials were very similar, suggesting that prolonging the functionalization duration had an insignificant effect on the physical characteristics of oxidized multiwalled carbon nanotubes (oxMWCNTs). Increasing the Ph of the solutions from Ph 2 to Ph 8 had a large positive impact on the removal of Cu(II) and Ni(II) by oxMWCNT, but reduced the adsorption of Cr(VI). However, the ionic strength of the solutions had far less pronounced effects. Coupled with the results of fitting the kinetics data to the Elowich and Weber–Morris models, we conclude that adsorption of Cu(II) and Ni(II) is largely driven by electrostatic interactions and surface complexation at the interface of the adsorbate/adsorbent system, whereas the slower adsorption of Cr(VI) on the oxMWCNTs investigated is controlled by an additional chemisorption step where Cr(VI) is reduced to Cr(III). Both oxMWCNT3h and oxMWCNT6h have high adsorption affinities for the heavy metals investigated, with adsorption capacities (expressed by the Freundlich coefficient KF) ranging from 1.24 to 13.2 (mg g−1)/(mg l−1)n, highlighting the great potential such adsorbents have in the removal of heavy metals from aqueous solutions.

Mechanical behaviour of MWCNTs reinforced electrospun nanofibres

The nanoscale dimension of electrospun polymeric nanofibres produced by electrospinning are highly captivating, yet facing limitation of resisting external forces due to the weak tensile properties. Carbon nanotubes providing tremendous toughness due to extraordinary strong sp2 bonding network of carbon atoms in honeycomb lattice structure, augmented the physical resistant strength and is easily recover to its original state after load is removed. This study reports the performance of multi-walled carbon nanotubes (MWCNTs) as filler in the electrospinning of poly (L-lactide)-co-ε-caprolactone) (PLCL) composite nanofibres. Voltage of 10 kV is applied to the spinning solution mixture of 11 wt% (w/v) PLCL and MWCNTs, yielded nanofibres having diameters less than 400 nm. Results obtained showed the formation of composite nanofibres with tailored tensile behavior by modifying the content of MWCNTs. The addition of MWCNTs improved the tensile properties of resultant composite nanofibres, signified by tensile strength of 5.82 to 15.95 MPa, which were obtained using 0.1 to 1.0 wt% of MWCNTs. The structural integrity of nanofibres mats were retained in phosphate buffer saline (PBS) medium. Scanning Electron Microscopy (SEM) micrographs revealed the minimal of fiber deformation over 30 days of incubation and are closely identical to the initial diameter of as-spun fiber.