Application Of Multiwalled Carbon Nanotubes Research Articles

In Vitro Biocompatibility Test of Multiwall Carbon Nanotubes with Human Osteoblast Cells: Potential Application for Bone Implant Interface Reinforcement.

Application of multiwall carbon nanotubes (MWCNT) as a filler component in composite materials can lead to remarkable increase in mechanical strength. It is a challenging application to form a living bone tissue biocomposite that is reinforced with MWCNTs at a dental implant-bone interface. The successful biointegration of MWCNT and the implant material depends on the processes of osseointegration, namely surface interactions at the molecular and cellular level. In this work the compatibility of MWCNT with main osseointegration processes has been overviewed with special attention to the toxicity of MWCNT for interacting human cells, and In Vitro experiments were performed with primary human osteoblast cells. The cells were isolated from oral bone fragments and grown in cell culture conditions. Plate wells were covered with MWCNT layers of three different densities. Osteoblast cell suspensions were placed onto the MWCNT layers and into empty plate wells. 24 and 72 hours after seeding the attachment and proliferation of cells was evaluated using Thiazolyl Blue Tetrazolium Bromide (MTT) colorimetric assay. The extent of cell death was characterized by Lactate Dehydrogenase (LDH) assay. The osteoblast cell viability tests show that cells were attached to all investigated surfaces, but with lower rate to higher density MWCNTs. A low level of cell death was observed in each sample type. Phase contrast and fluorescent microscopic observations show that although MWCNTs are not toxic for human primary osteoblast cells, an intense interaction of the cells with MWCNTs reduces their proliferation and markedly affects their morphology.

Preparation of diameter-controlled free-standing MWCNT membranes and their application for dye adsorption.

The synthesis of multi-walled carbon nanotubes (MWCNTs) was carried out over different Ni-loaded metallic oxide catalyst nanoparticles and under different reduction times to control the outside diameter of the nanotubes. Moreover, high-purity, free-standing membranes were fabricated by a simple filtration of the as-grown MWCNTs. Furthermore, the dye-adsorption properties of the nanotubes depended on the diameter of the carbon nanotubes (CNTs). The adsorption isotherms and kinetics of anionic dyes could be described by Freundlich and pseudo-second-order models, respectively. Thermodynamic studies suggested that the adsorption processes were spontaneous and exothermic. This work provides new insights into the synthesis and application of MWCNTs with the selective adsorption properties of carbon-based materials for the removal of organic dyes.

Selective Uptake of Carboxylated Multi-Walled Carbon Nanotubes by Class A Type 1 Scavenger Receptors and Impaired Phagocytosis in Alveolar Macrophages

The production and applications of multi-walled carbon nanotubes (MWNTs) have increased despite evidence that MWNTs can be toxic. Recently, we reported that the binding of Pluronic® F-108 (PF108)-coated carboxylated MWNTs (C-MWNTs) to macrophages is inhibited by class A scavenger receptors (SR-As) antagonists (R. Wang et al., 2018. Nanotoxicology 12:677–690). The current study investigates the uptake of PF108-coated MWNTs by macrophages lacking SR-A1 and by CHO cells that ectopically express SR-A1. Macrophages without SR-A1 failed to take up C-MWNTs and CHO cells that expressed SR-A1 did take up C-MWNTs, but not pristine MWNTs (P-MWNTs) or amino-functionalized MWNTs (N-MWNTs). The dependence of C-MWNT uptake on SR-A1 is strong evidence that SR-A1 is a receptor for C-MWNTs. The consequences of SR-A1-dependent C-MWNT accumulation on cell viability and phagocytic activity in macrophages were also studied. C-MWNTs were more toxic than P-MWNTs and N-MWNTs in cell proliferation and colony formation tests. C-MWNTs reduced surface SR-A1 levels in RAW 264.7 cells and impaired phagocytic uptake of three known SR-A1 ligands, polystyrene beads, heat-killed E. coli, and oxLDL. Altogether, results of this study confirmed that SR-A1 receptors are important for the selective uptake of PF108-coated C-MWNTs and that accumulation of the C-MWNTs impairs phagocytic activity and cell viability in macrophages.

Study on Glucose Sensing Materials Based on CNT/Graphene-Ag Composite for Nano-Electrode Sensor

Sensors are already part of everyday life, and they are based on a mechanical and electronic pattern such as what humans see, hear and do, and they have a wide range of uses and a wide variety of types. The material that forms a sensor and its structure are very important to perform the sensing role. Electrochemical method is a kind of technology that has been promoted in modern environmental pollutant detection technology. It attracts the attention and interests of many researchers with various advantages. There are many kinds of pollution, and the persistent organic pollutants are especially harmful. Therefore, there is an urgent need to be able to quickly and accurately detect environmental pollution in the in situ method. With the development of nanotechnology, great potential has been created for the design of low-energy consumption, low-cost, high-sensitivity sensors. Due to the properties of carbon nano tube (CNT) and graphene, the combination between C-C and C-C is hexagonal in the nanostructures, which has a great reactivity and are also very stable in high temperature, high pressure, and acid conditions.Carbon Nano Tube (CNT) as nanomaterials have excellent electrical conductivity, high specific surface area and hollow structure, so it can be ideal sensor materials. Based on the excellent properties of the CNT, if the composite material is constructed, this type of material has many new properties at the same time. If such a composite material is used as an electrode, an oxidation-reduction reaction occurs between the contaminant and the electrode, which achieves the purpose of an electrochemical sensor.Synergy effect is achieved by making Metal Nano Composite based on CNT/graphene nanomaterials.These composites have both the characteristics of CNT / graphene and metal, and to make composite with these properties, uniformly plated process and surface treatment technology are required. To manufacture these composite materials, we fabricate Ag-CNT/graphene, optimized the Ag electroless plating (ELP) method for uniform aggregation on CNT/graphene, and optimize the process for the plating solution using the Raman in-situ method. The technique of analyzing the reaction process has been attracting attention from the past. It is very difficult to analyze the process in a chemical reaction because the chemical reaction causes a real-time change in molecular vibration due to a change in binding force. Therefore, there is an urgent need to be able to quickly and accurately detect a chemical reaction in in-situ method. Many electrodes can be formed by electro-less plating (ELP) technique in the sensor process, which enables low-cost and high-efficiency processing. In particular, the greatest advantage of the ELP process is that it can form layers on the nanoscale. In order to uniformly deposit Ag nanoparticles with antimicrobial activity on the surfaces of commercially available nanofilters, it is necessary to process the deposition process in real time and analyze easily.This work mainly studies the application of Multi walled CNT (MWCNT) and MWCNT composite modified electrode in the electrochemical sensor. We aimed to maximize the sensitivity of the sensor by proceeding with silver electroless plating for MWCNT and MWCNT composite. Oxidation of MWCNT showed a stronger plating effect and the pretreatmented MWCNT has a better effect.

Multi wall carbon nanotubes application for treatment of Cr(VI)-contaminated groundwater; Modeling of batch & column experiments

Multi wall carbon nanotubes (MWCNTs) are carbonaceous nanomaterials with novel adsorption properties. In this study MWCNTs were used as adsorbents for hexavalent chromium, Cr(VI), and the influence of operating parameters, on adsorption process, such as pH, MWCNTs and Cr(VI) concentration, and contact time have been investigated. Batch and column experiments were carried out in order to investigate the removal efficiency of MWCNTs for different Cr(VI) concentrations related to groundwater polluted by either anthropogenic activities or by geogenic processes. The experimental results showed that pH was the most crucial factor for adsorption efficiency. Cr(VI) adsorption was inversely proportional with pH value and more specifically adsorption was significantly decreased for pH values higher than 7. The effect of adsorbent’s concentration showed the high adsorption capacity of MWCNTs. The adsorption process was very fast since was almost completed within 1 h. Different isotherm models have been adopted to interpret the experimental equilibrium data, as well as two mass-transfer based model were used to describe the dynamic behavior of Cr(VI) sorption phenomenon in column experiments.

Anti-radar application of multiwalled carbon nanotubes and zinc oxide synthesized using a hydrothermal method

Anti-radar technology is essential to reinforce countries defense capacity. Previous studies have shown how the combination of a resistive material with a magnetic one is a good option for the development of radar absorbing materials. Multiwalled carbon nanotube (MWCNT)/ZnO material with MWCNT percentage variations of 1, 3, 5, and 7% has been proposed as a promising material in anti-radar technology. ZnO that is used in the synthesis of MWCNT/ZnO material resulting from a hydrothermal method was prepared using ZnSO4 and Na2CO3 as precursors. X-ray diffractograms show hexagonal phases for both MWCNT and ZnO, in the latter case hexagonal wurtzite. SEM analysis shows micrometer sheets for ZnO. The VNA test in the X-band frequency range (8 − 12.5 GHz) provides the reflection loss values. Based on the reflection loss value, MWCNT/ZnO material has an optimum absorption value of electromagnetic waves with a percentage of 3% MWCNT at a frequency of 11.2 GHz with an RL value of −31.4535 dB and a percentage of 7% MWCNT at a frequency of 11.2 GHz with an RL value of −25.3897 dB.

Application of Multi-Walled Carbon Nanotubes based Materials in Heavy Metals Adsorption

Application of Multi-Walled Carbon Nanotubes based Materials in Heavy Metals Adsorption

Studies on chip morphology and modes of tool wear during machining of Ti-6Al-4V using uncoated carbide tool: application of multi-walled carbon nanotubes added rice bran oil as nanocutting fluid

In this work, machining performance of Ti-6Al-4V is studied in consideration with cutting force, tool-tip temperature, tool wear mechanisms, chip morphology and roughness of the machined surface. Machining experiments are carried out by varying cutting speed (Vc) with constant feed and depth-of-cut. Uncoated WC-Co insert is used as cutting tool. Multi-walled carbon nanotubes (MWCNTs) added rice bran oil is utilized to produce nanofluid minimum quantity lubrication (MQL) environment. Chip morphology along with measurable geometrical parameters including chip-tool contact length, equivalent chip thickness (H ch), segmentation spacing, segmentation frequency, shear band width, shear angle, chip hardness, etc. are studied in detail. Effects of Vc on cutting force, tool-tip temperature, depth of flank wear, and area of crater wear are discussed. Different tool wear mechanisms are identified as well. It is experienced that nanofluid MQL (NFMQL) outperforms traditional dry cutting as well as conventional MQL in purview of improved process performance.

Diatom-frustule catalyst supported multiwalled carbon nanotubes: Scalable and cost-effective synthesis and stable anode for lithium-ion battery

Multiwalled carbon nanotubes have interesting electrochemical properties that can be utilized for the energy storage application. However, the practical application of multiwalled carbon nanotubes is limited by the current techniques to provide large scale production. So, the large scale production of multiwalled carbon nanotubes is obtained by catalytic chemical vapor deposition of acetylene/liquified petroleum gas on diatom supported Mischmetal based nickel alloy catalyst. The developed multiwalled carbon nanotubes are uniform in diameter and the method of production does not require any process of purification. The multiwalled carbon nanotubes along with the presence of diatom is used as the high capacity anode for the lithium-ion battery. The interaction of lithium ions with both multiwalled carbon nanotubes and diatom increases the specific capacity to 1090 mAh g−1 at 0.05 A g−1 with cyclic durability of 2000 cycles. This work demonstrates a scalable method for the production of multiwalled carbon nanotubes from a cost-effective catalyst with the benefit of utilizing it as a high capacity anode material for lithium-ion battery.

Effect of Multi-Wall Carbon Nanotubes on the Microhardness of the Tooth Enamel

Background: The object of this study was to investigate the effect of addition of Multi-Wall Carbon Nano Tubes (MWCNTs) in different concentration (0.001g/20ml, 0.005g/20ml , 0.01g/20ml and 0.02g/20ml) in (dimethyl sulphoxide) to tooth enamel. It is intended to evaluate enamel hardness in (Kg .m-2) before and after the addition of (MWCNTs). Materials and Method: Thirty specimens were prepared for this study, to measure the hardness of the enamel. Results: The results enamel hardness after MWCNTs application With DMSO showed a significant increase (P<0.01) between groups of 0.001g/20ml , 0.005 g/20ml , 0.01 g/20ml and , 0.02 g/20ml concentration compared with control group. Where the highest mean value obtained was in 0.02g/20ml concentration which had a mean value of 527.18 ± 2.904 Kg .m-2 , while the lowest mean value was for control group which had a mean value of 334.87± 2.904 Kg .m-2. Polished enamel surface groups showed a significant increase 452.59 ± 1.84 Kg .m-2 (P<0.01) in hardness when compared with unpolished enamel surface groups 430.16 ± 1.84 Kg .m-2 (P<0.01). Conclusion: The highest mean value obtained was in 0.02g/20ml concentration in the hardness suspended in DMSO. The results showed a significant increase in the hardness for polished enamel surface samples compared with unpolished enamel surface samples in DMSO.

An Overview of the Properties and Biomedical Applications of Multi-Walled Carbon Nanotubes

The unique combination of electrical, mechanical and electrochemical properties offered by multi-walled carbon nanotubes (MWCNTs) has emerged as a potential element for their use in many kinds of applications including biomedical fields. In this article, the crystallographic structural and electrical properties of multi-walled carbon nanotubes (MWCNTs) have been discussed briefly. Finally the article concludes by focusing the key properties of MWCNTs which fostered their use in various biomedical applications, such as drug delivery, cancer treatment, gene therapy and diagnostics.

2k Optimization approach for the removal of Pb2+ ions from water contaminated from oil-well drilling point on to MWCNTs

The release of Pb2+ into the surrounding ecosystem has adverse effects on man and animal, hence, removing such harmful heavy metal from water system calls for urgent attention. The potential application of Multi-walled carbon nanotubes, MWCNTs, towards the lead (II) ions removal from oil polluted water body was studied and optimized via 2k factorial experimental approach. The MWCNTs produced was characterized via High Resolution Transmission Electron Microscope (HR-TEM), High Resolution Scanning Electron microscope (HR-SEM), Thermogravimetric Analysis (TGA), Fourier Transform Infrared (FTIR) and Brenuer-Emmette-Teller (BET) to determine the internal morphology, surface morphology, thermal stability, functional group and surface area respectively. The results of the HR-TEM depict the nano-structural diameter of the produced MWCNTs with continuous strands of tubes as depicted by SEM micrograph. The MWCNTs surface area produced was obtained to be 540 m2/g. The sorption of Pb2+ ions was optimized using 2k design approach where speed (rpm), absorbent dosage (g), temperature (°C) and time (min) were studied in a batch condition. The optimum conditions that give maximum sorption of Pb2+ ions on to the surfaces and the pores of the developed MWCNTs adsorbent were obtained at 60 min contact time, 59.89 °C, 0.20 g of adsorbent dosage and 599.98 rpm of agitation. Thus, the highest percentage sorption of Pb2+ ions by the MWCNTs from the oil-polluted water body was 99.5%. Hence, this study has demonstrated the potentials of MWCNTs as an effective and efficient sorbent for Pb2+ sorption from oil polluted wastewater.

Nitrogen-Doped Carbon Nanotube/Polypropylene Composites with Negative Seebeck Coefficient

This study describes the application of multi-walled carbon nanotubes that were nitrogen-doped during their synthesis (N-MWCNTs) in melt-mixed polypropylene (PP) composites. Different types of N-MWCNTs, synthesized using different methods, were used and compared. Four of the five MWCNT grades showed negative Seebeck coefficients (S), indicating n-type charge carrier behavior. All prepared composites (with a concentration between 2 and 7.5 wt% N-MWCNTs) also showed negative S values, which in most cases had a higher negative value than the corresponding nanotubes. The S values achieved were between 1.0 μV/K and −13.8 μV/K for the N-MWCNT buckypapers or powders and between −4.7 μV/K and −22.8 μV/K for the corresponding composites. With a higher content of N-MWCNTs, the increase in electrical conductivity led to increasing values of the power factor (PF) despite the unstable behavior of the Seebeck coefficient. The highest power factor was achieved with 4 wt% N-MWCNT, where a suitable combination of high electrical conductivity and acceptable Seebeck coefficient led to a PF value of 6.1 × 10−3 µW/(m·K2). First experiments have shown that transient absorption spectroscopy (TAS) is a useful tool to study the carrier transfer process in CNTs in composites and to correlate it with the Seebeck coefficient.

Glucose Sensing Materials Based on Carbon Nanotubes for Electrochemical Sensing

There is an urgent need for in situ methods for detecting environmental pollution quickly and accurately. With the development of nanotechnology, a huge potential has been created for the design of highly sensitive sensors with low energy consumption and low costs. If a composite material constructed with carbon nanotubes is used as an electrode in contact with a contaminant, this material undergoes an oxidation-reduction reaction with the contaminant that allows the electrode to function as an electrochemical sensor. This study involved the application of multi-walled carbon nanotubes and modified working electrodes constructed with multi-walled carbon nanotube composites (Ag- and ZnO-multi-walled carbon nanotubes) as electrochemical sensors. These electrodes have good response speed and sensitivity at low concentrations, and they are reusable. To lower the price of these sensors, our goal was to maximize their sensitivity by using the low-cost multiwalled carbon nanotubes in conjunction with silver electroless plating of the multi-walled carbon nanotubes and multi-walled carbon nanotube composites.

Electronic applications of multi-walled carbon nanotubes in polymers: A short review

In today’s nano scale regime, a smart electronic device is attractive and has a primary role for majority of the world’s research community, particularly scientific and engineering community. Quasi one-dimensional carbon materials are an ideal material for flexible and wearable electronic applications. Significant progress has been made in developing electronics using carbon-based polymer composites. The incorporation of micro-materials and carbon nanomaterials in polymer has been attempted since the 1990 s and has shown a number of improved properties. In this review, the performance of the polymer composite with nanophase carbon materials is explored and their applications are discussed. In recent years, a wide range of carbon nanomaterials are used to transmit electrical signals for potential applications such as electronics, chemical sensors, mechanical sensors/actuators, and smart materials. Moreover, we have also discussed carbon-based materials, especially multi-walled carbon nanotubes, that are applied on a substrate using some printing technology for flexible electronics, and the progress of CNT-based RF antenna, textile, electromagnetic and interference shielding, and sensor applications has been reported.

IMPACT OF MULTI-WALLED CARBON NANOTUBES ON WOOD SAWDUST EXTRACT CEMENT MORTAR

It is well known that organic waste materials deteriorate the performance of concrete. The impregnation of organic aggregates and their application in combination with other chemical admixtures and mineral additives are used in order to improve the concrete properties in case of their modification by organic components. The current research is focused on the evaluation of impact of multi-walled carbon nanotubes (MWCNT) on the properties of cement systems prepared based on wood sawdust extract (WSE). The setting time, density, consistency, flexural and compressive strength, water absorption tests were undertaken. The retardation effect of (WSE) on the initial and final setting time of cement paste was observed. The additional modification of cement paste with WSE by MWCNT in the dosage of 0.005% by weight of cement (bwoc) did not show the significant changes in initial and final setting time. The application of MWCNT in the dosage of 0.005% bwoc contributed to the increase of early strength of cement mortar prepared with WSE.

Void characteristics and mechanical strength of cementitious mortars containing multi-walled carbon nanotubes

In this paper, the relationship between mechanical strength and void characteristics including porosity, the mean area of voids (MAV), and circularity was determined for the first time by analyzing the petrographic images of some cement mortars containing multi-walled carbon nanotubes (MWCNTs). The results showed that the compressive, tensile, and flexural strength for specimens containing 0.1% MWCNTs (optimum dosage of MWCNT) were 21, 12.5, and 9.5% more than that of the control samples, respectively. Also, it was shown that the application of MWCNTs can change the shape and the amount of voids, thereby imposing a significant impact on the mortar behavior. For the optimum dosage of MWCNTs, the porosity and MAV decreased about 63 and 71%, respectively, while the circularity enhanced 23% in comparison with the ordinary mortar samples. The void shape is one of the reasons for the enhanced properties of the MWCNT mortars. The image processing of the petrographic specimens and probability theorization revealed that the circularity of the voids had a significant impact on the flexural strength of the mortars, while the compressive strength was mostly affected by only the amount of porosity.

Development of a Novel Shallow Liquid Interface Exposure System for MWCNT Toxicity Assessment.

Increasing applications of multiwalled carbon nanotubes (MWCNT) lead to significant occupational exposure and potential health concerns. Toxicity of MWCNT should be carefully elucidated since the conventional (CON) method with fully immersed condition fails to mimic the air-liquid interface (ALI) in airways. Additionally, quantification of MWCNT in cells was a real challenge. Currently available ALI exposure devices are costly, posing problems to conducting in vitro evaluations for emerging nanomaterials. A novel system, consisting of a shaker fluidized-bed atomizer (SFA) and electrostatic shallow liquid interface (ESLI) exposure chamber, has been developed for investigating nanotoxicity of well-dispersed pristine-MWCNT (pMWCNT) and carboxylized-MWCNT (cMWCNT). After 24-h exposure, LDH, MCP-1, IL-1β, IL-6, and TNF-α releases were determined, and cell uptakes were quantified according to the molybdenum content in cells. Biological responses triggered by SLI exposure are obviously more sensitive compared with those caused by CON exposure at equivalent doses. Exposure dose-dependent release of LDH and IL-6 was highlighted in A549 cells, indicating higher cytotoxicity and inflammatory responses of cMWCNT attributed to its shorter length, smaller size, and higher cell uptake. Cell-associated dose-dependent release of LDH and IL-6 was highlighted in RAW264.7 cells, revealing the higher adverse health risk of pMWCNT due to frustrated phagocytosis and its much higher molybdenum content. These results suggest that inherent characteristics of cells and distinct physicochemical properties of pMWCNT and cMWCNT lead to either exposure dose-dependent or cell-associated dose-dependent responses. Notably, the SLI is superior to the CON exposure method and well suited for nanotoxicity assessment of different MWCNTs.

The effect of cations on gelation of cross-linked polymers

The effects of different cation concentrations and types on rheological property and stability of Guar, Xanthan, and Partially Hydrolyzed Polyacrylamide (HPAM) cross-linked gels were analyzed through experiments. Also, a new approach was developed to reduce the negative effects of cation by application of multi-walled carbon nano-tubes (MWCNTs). The presence of cations in cross-linked gel system will reduce the viscosity of gel, the higher the cation concentration is, the lower the viscosity will be. The bivalent cation has a greater viscosity reduction effect on gel than monovalent cation. The stability of cross-linked gels is worse with cations, this situation becomes more serious under higher salinity. MWCNTs were added to HPAM gel, cross-linked by (3-Aminopropyl) triethoxysilane (APTES), they surrounded cations and removed them from polymers and reduced the reaction possibility. This method enhances the viscosity and breakdown pressure of cross-linked gels, improves the stability of HPAM cross-linked gel under different operating conditions, and can be applied to related drilling projects.

EDM performance of Inconel 718 superalloy: application of multi-walled carbon nanotube (MWCNT) added dielectric media

Electro-discharge machining (EDM) is very promising non-traditional machining route to cut ‘difficult-to-machine’ materials like Inconel 718 superalloy. However, low material removal efficiency and inferior surface integrity restricts EDM application on Inconel 718. In order to improve EDM performance, multi-walled carbon nanotube (MWCNT) dispersed into kerosene is explored as dielectric media. Experiments are conducted by varying peak discharge current with a fixed concentration of MWCNT (0.5 g/l) added to kerosene. EDM performance is assessed in purview of material removal efficiency, tool wear rate, and surface integrity (morphology and topography) of the EDMed specimen. Apart from morphological study, surface topography including surface roughness, crack density, recast layer thickness, metallographic alteration, residual stress, and micro-indentation hardness of the machined specimen are studied in detail. It is concluded that as compared to conventional EDM, use of MWCNT-mixed dielectric media (0.5 g/l) significantly improves machining performance.