Search results for: functionalized carbon nanotubes

Authors: B. V. Bhaskara Rao, Rodrigo Espinoza

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The rapid development of renewable energy sources has drawn great attention to energy storage devices, especially supercapacitors, because of their high power density and rate performance. This work focus on Fe₃O₄ nanoparticles synthesized by reverse co-precipitation and MWCNTs functionalized by –COOH acid functionalization. The results show that Optimized 25wt% Fe₃O₄@FMWCNT show high specific capacitance 100 mF/cm² at one mA/cm² whereas 15wt% Fe₃O₄@FMWCNT showed high stability (80% retention capacity) over 5000 cycles. The electrolyte used in the coin cell is LiPF6 and the thickness of the electrode is 30 microns. The optimized Fe₃O₄@FMWCNT bucky papers coin cell electrochemical studies suggest that 25wt% Fe₃O₄@FMWCNT could be a good candidate for high-capacity supercapacitor devices. This could be further tested for flexible and planar supercapacitor device application with gel electrolytes.

Keywords: self-standing electrode, Fe₃O4@FMWCNT, supercapacitor, symmetric coin-cell

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Authors: Illyas Md Isa, Sharifah Norain Mohd Sharif, Norhayati Hashim

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A mercury(II) sensor was developed by using multi-walled carbon nano tubes (MWCNTs) paste electrode modified with Zn/Al layered double hydroxide-3(4-methoxyphenyl) propionate nano composite (Zn/Al-HMPP). The optimum conditions by cyclic voltammetry were observed at electrode composition 2.5% (w/w) of Zn/Al-HMPP/MWCNTs, 0.4 M potassium chloride, pH 4.0, and scan rate of 100 mVs-1. The sensor exhibited wide linear range from 1x10-3 M to 1x10-7 M Hg2+ and 1x10-7 M to 1x10-9 M Hg2+, with a detection limit of 1 x 10-10 M Hg2+. The high sensitivity of the proposed electrode towards Hg(II) was confirmed by double potential-step chronocoulometry which indicated these values; diffusion coefficient 1.5445 x 10-9 cm2 s-1, surface charge 524.5 µC s-½ and surface coverage 4.41 x 10-2 mol cm-2. The presence of 25-fold concentration of most metal ions had no influence on the anodic peak current. With characteristics such as high sensitivity, selectivity and repeatability the electrode was then proposed as the appropriate alternative for the determination of mercury.

Keywords: Cyclic voltammetry, Mercury(II), Modified carbon paste electrode, Nanocomposite

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Authors: Ling Ai, Ziyu Zhao, Zeyu Zhou, Xiaochen Yang, Heng Zhai, Stuart Holmes

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Optimizing the catalyst layer structure is crucial for enhancing the performance of proton exchange membrane fuel cells (PEMFCs) with low Platinum (Pt) loading. Current works focused on the utilization, durability, and site activity of Pt particles on support, and performance enhancement has been achieved by loading Pt onto porous support with different morphology, such as graphene, carbon fiber, and carbon black. Some schemes have also incorporated cost considerations to achieve lower Pt loading. However, the design of the catalyst layer (CL) structure in the membrane electrode assembly (MEA) must consider the interactions between the layers. Addressing the crucial aspects of water management, low contact resistance, and the establishment of effective three-phase boundary for MEA, multi-walled carbon nanotubes (MWCNTs) are promising CL support due to their intrinsically high hydrophobicity, high axial electrical conductivity, and potential for ordered alignment. However, the drawbacks of MWCNTs, such as strong agglomeration, wall surface chemical inertness, and unopened ends, are unfavorable for Pt nanoparticle loading, which is detrimental to MEA processing and leads to inhomogeneous CL surfaces. This further deteriorates the utilization of Pt and increases the contact resistance. Robust chemical oxidation or nitrogen doping can introduce polar functional groups onto the surface of MWCNTs, facilitating the creation of open tube ends and inducing defects in tube walls. This improves dispersibility and load capacity but reduces length and conductivity. Consequently, a trade-off exists between maintaining the intrinsic properties and the degree of functionalization of MWCNTs. In this work, MWCNTs were modified based on the operational requirements of the MEA from the viewpoint of interlayer interactions, including the search for the optimal degree of oxidation, N-doping, and micro-arrangement. MWCNT were functionalized by oxidizing, N-doping, as well as micro-alignment to achieve lower contact resistance between CL and proton exchange membrane (PEM), better hydrophobicity, and enhanced performance. Furthermore, this work expects to construct a more continuously distributed three-phase boundary by aligning MWCNT to form a locally ordered structure, which is essential for the efficient utilization of Pt active sites. Different from other chemical oxidation schemes that used HNO3:H2SO4 (1:3) mixed acid to strongly oxidize MWCNT, this scheme adopted pure HNO3 to partially oxidize MWCNT at a lower reflux temperature (80 ℃) and a shorter treatment time (0 to 10 h) to preserve the morphology and intrinsic conductivity of MWCNT. The maximum power density of 979.81 mw cm-2 was achieved by Pt loading on 6h MWCNT oxidation time (Pt-MWCNT6h). This represented a 59.53% improvement over the commercial Pt/C catalyst of 614.17 (mw cm-2). In addition, due to the stronger electrical conductivity, the charge transfer resistance of Pt-MWCNT6h in the electrochemical impedance spectroscopy (EIS) test was 0.09 Ohm cm-2, which was 48.86% lower than that of Pt/C. This study will discuss the developed catalysts and their efficacy in a working fuel cell system. This research will validate the impact of low-functionalization modification of MWCNTs on the performance of PEMFC, which simplifies the preparation challenges of CL and contributing for the widespread commercial application of PEMFCs on a larger scale.

Keywords: carbon nanotubes, electrocatalyst, membrane electrode assembly, proton exchange membrane fuel cell

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Authors: Nidal H. Abu-Zahra, Subhashini Gunashekar

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Polyurethane foam is functionalized with Sulfonic acid groups to remove lead ions (Pb2+) from drinking water through a action exchange process. The synthesis is based on addition polymerization of the -NCO groups of an isocyanine with the –OH groups of a polio to form the urethane. Toluene-diisocyanateis reacted with Polypropylene glycol to form a linear pre-polymer, which is further polymerized using a chain extender, N, N-bis(2-hydorxyethyl)-2-aminoethane-sulfonic acid (BES). BES acts as a functional group site to exchange Pb2+ ions. A set of experiments was designed to study the effect of various processing parameters on the performance of the synthesized foam. The maximum Pb2+ ion exchange capacity of the foam was found to be 47ppb/g from a 100ppb Pb2+ solution over a period of 60 minutes. A multistage batch filtration process increased the lead removal to 50-54ppb/3g of foam over a period of 90 minutes.

Keywords: adsorption, functionalized, ion exchange, polyurethane, sulfonic

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Authors: M. Rajabi, O. Moradi

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In this study, removal of Nickel and Zinc by graphene oxide and functionalized graphene oxide–gelaycin surfaces was examined. Amino group was added to surface of graphene oxide to produced functionalized graphene oxide–gelaycin. Effect of contact time and initial concentration of Ni (II) and Zn(II) ions were studied. Results showed that with increase of initial concentration of Ni (II) and Zn(II) adsorption capacity was increased. After 50 min has not a large change at adsorption capacity therefore, 50 min was selected as optimaze time. Scanning electron microscope (SEM) and fourier transform infrared (FT-IR) spectroscopy spectra used for the analysis confirmed the successful fictionalization of the Graphene oxide surface. Adsorption experiments of Ni (II) and Zn(II) ions graphene oxide and functionalized graphene oxide–gelaycin surfaces fixed at 298 K and pH=6. The Pseudo Firs-order and the Pseudo Second-order (types I, II, III and IV) kinetic models were tested for adsorption process and results showed that the kinetic parameters best fits with to type (I) of pseudo-second-order model because presented low X2 values and also high R2 values.

Keywords: graphene oxide, gelaycin, nickel, zinc, adsorption, kinetic, graphene oxide, gelaycin, nickel, zinc, adsorption, kinetic

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Authors: Soon Ok Jo, Han Kyu Jeung, Si Woo Park

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With the process of consistent expansion of carbon fiber in width (Carbon Fiber Tow Spreading Technique), it can be expected that such process can enhance the production of carbon fiber reinforced composite material and quality of the product. In this research, the method of mechanically expanding carbon fiber and increasing its width was investigated by using various geometric rolls. In addition, experimental type of carbon fiber expansion device was developed and tested using 12K carbon fiber. As a result, the effects of expansion of such fiber under optimized operating conditions and geometric structure of an elliptical roll, were analyzed.

Keywords: carbon fiber, tow spreading fiber, pre-preg, roll structure

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Authors: Abdulmagid A. Khattabi, Ahmed A. Hablous, Mofied M. Elnemry

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The carbon steel is of one of the most common mineral materials used in engineering and industrial applications in order to have access to the required mechanical properties, especially after the change of carbon ratio, but this may lead to stimulate corrosion. It has been used in models of solids with different carbon ratios such as 0.05% C, 0.2% C, 0.35% C, 0.5% C, and 0.65% C and have been studied using three testing durations which are 4 weeks, 6 weeks, and 8 weeks and among different corrosion environments such as atmosphere, fresh water, and salt water. This research is for the purpose of finding the effect of the carbon content on the corrosion resistance of steels in different corrosion medium by using the weight loss technique as a function of the corrosion resistance. The results that have been obtained through this research shows that a correlation can be made between corrosion rates and steel's carbon content, and the corrosion resistance decreases with the increase in carbon content.

Keywords: proportion of carbon in the steel, corrosion rate, erosion, corrosion resistance in carbon-steel

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Authors: Alexander Rodríguez-Hernández, Arnulfo Rojas-Perez, Liz Diaz-Vazquez

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The rise in consumerism over the past century has resulted in the creation of higher amounts of plasticizers, personal care products and other chemical substances, which enter and accumulate in water systems. Other sources of pollutants in Neotropical regions experience large inputs of nutrients with these pollutants resulting in eutrophication of water which consume large quantities of oxygen, resulting in high fish mortality. This dilemma has created a need for the development of targeted detection in complex matrices and remediation of emerging contaminants. We have synthesized carbon nanoparticles from macro algae (Ulva fasciata) by oxidizing the graphitic carbon network under extreme acidic conditions. The resulting material was characterized by STEM, yielding a spherical 12 nm average diameter nanoparticles, which can be fixed into a polysaccharide aerogel synthesized from the same macro algae. Spectrophotometer analyses show a pH dependent fluorescent behavior varying from 450-620 nm in aqueous media. Heavily oxidized edges provide for easy functionalization with enzymes for a more targeted analysis and remediation technique. Given the optical properties of the carbon base nanoparticles and the numerous possibilities of functionalization, we have developed a selective and robust targeted bio-detection and bioremediation technique for the treatment of emerging contaminants in complex matrices like estuarine embayment.

Keywords: aerogels, carbon nanoparticles, fluorescent, targeted analysis

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Authors: Tayyaba Ghani, Mazhar Mehmood, Mohammad Mujahid

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TiO₂ nanotubes are receiving immense attraction in the field of dye-sensitized solar cells due to their well-defined nanostructures, efficient electron transport and large surface area as compared to other one dimensional structures. In the present work, we have investigated the influence of temperature on the morphology of anodically produced self-organized Titanium oxide nanotubes (TiNTs). TiNTs are synthesized by two-step anodization method in an ethylene glycol based electrolytes containing ammonium fluoride. Experiments are performed at constant anodization voltage for two hours. An investigation by the SEM images reveals that if the temperature is kept constant during the anodizing experiment, variation in the average tube diameter is significantly reduced. However, if the temperature is not controlled then due to the exothermic nature of reactions for the formation of TiNTs, the temperature of electrolyte keep on increasing. This variation in electrolyte bath temperature introduced strong variations in tube diameter (20 nm to 160 nm) along the length of tubes. Current profiles, recorded during the anodization experiment, predict the effect of constant and varying experimental temperatures as well. In both cases, XRD results show the complete anatase crystal structure of nanotube upon annealing at 450 °C. Present work highlights the importance of constant temperature during the anodization experiments in order to develop an ordered array of nanotubes with a uniform tube diameter.

Keywords: anodization, ordering, temperature, TiO₂ nanotubes

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Authors: Giulia Fredi, Andrea Dorigato, Luca Fambri, Alessandro Pegoretti

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Thermal energy storage (TES) is the storage of heat for later use, thus filling the gap between energy request and supply. The most widely used materials for TES are the organic solid-liquid phase change materials (PCMs), such as paraffin. These materials store/release a high amount of latent heat thanks to their high specific melting enthalpy, operate in a narrow temperature range and have a tunable working temperature. However, they suffer from a low thermal conductivity and need to be confined to prevent leakage. These two issues can be tackled by confining PCMs with carbon nanotubes (CNTs). TES applications include the buildings industry, solar thermal energy collection and thermal management of electronics. In most cases, TES systems are an additional component to be added to the main structure, but if weight and volume savings are key issues, it would be advantageous to embed the TES functionality directly in the structure. Such multifunctional materials could be employed in the automotive industry, where the diffusion of lightweight structures could complicate the thermal management of the cockpit environment or of other temperature sensitive components. This work aims to produce epoxy/carbon structural laminates containing CNT-stabilized paraffin. CNTs were added to molten paraffin in a fraction of 10 wt%, as this was the minimum amount at which no leakage was detected above the melting temperature (45°C). The paraffin/CNT blend was cryogenically milled to obtain particles with an average size of 50 µm. They were added in various percentages (20, 30 and 40 wt%) to an epoxy/hardener formulation, which was used as a matrix to produce laminates through a wet layup technique, by stacking five plies of a plain carbon fiber fabric. The samples were characterized microstructurally, thermally and mechanically. Differential scanning calorimetry (DSC) tests showed that the paraffin kept its ability to melt and crystallize also in the laminates, and the melting enthalpy was almost proportional to the paraffin weight fraction. These thermal properties were retained after fifty heating/cooling cycles. Laser flash analysis showed that the thermal conductivity through the thickness increased with an increase of the PCM, due to the presence of CNTs. The ability of the developed laminates to contribute to the thermal management was also assessed by monitoring their cooling rates through a thermal camera. Three-point bending tests showed that the flexural modulus was only slightly impaired by the presence of the paraffin/CNT particles, while a more sensible decrease of the stress and strain at break and the interlaminar shear strength was detected. Optical and scanning electron microscope images revealed that these could be attributed to the preferential location of the PCM in the interlaminar region. These results demonstrated the feasibility of multifunctional structural TES composites and highlighted that the PCM size and distribution affect the mechanical properties. In this perspective, this group is working on the encapsulation of paraffin in a sol-gel derived organosilica shell. Submicron spheres have been produced, and the current activity focuses on the optimization of the synthesis parameters to increase the emulsion efficiency.

Keywords: carbon fibers, carbon nanotubes, lightweight materials, multifunctional composites, thermal energy storage

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Authors: Sajjad Seifoori

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Impact behavior of striker on graphene sheet and carbon nanotube is investigated based on molecular dynamics (MD) simulations. A MD simulation is conducted to obtain the maximum dynamic deflections of a square and rectangular single-layered graphene sheets (SLGSs) with various values of side-length and striker parameter. Effect of (i) chirality, (ii) graphene side-length and nanotube length, (iii) striker mass on the maximum dynamic deflections of graphene and nanotube are investigated. The effect of different types of boundary condition on the maximum dynamic deflections is studied for zigzag and armchair SWCNTs with various aspect ratios (Length/Diameter).

Keywords: impact, molecular dynamic, graphene, spring mass

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Authors: H. K. Shahzad, M. A. Hussein, F. Patel, N. Al-Aqeeli, T. Laoui

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The purpose of the present study was to use the adsorption mechanism with microfiltration synergistically for efficient heavy metal removal from contaminated water. Alumina (Al2O3) is commonly used for ceramic membranes development while recently carbon nanotubes (CNTs) have been considered among the best adsorbent materials for heavy metals. In this work, we combined both of these materials to prepare porous Al2O3-CNTs nanocomposite membranes via Spark Plasma Sintering (SPS) technique. Alumina was used as a base matrix while CNTs were added as filler. The SPS process parameters i.e. applied pressure, temperature, heating rate, and holding time were varied to obtain the best combination of porosity (64%, measured according to ASTM c373-14a) and strength (3.2 MPa, measured by diametrical compression test) of the developed membranes. The prepared membranes were characterized using X-ray diffraction (XRD), field emission secondary electron microscopy (FE-SEM), contact angle and porosity measurements. The results showed that properties of the synthesized membranes were highly influenced by the SPS process parameters. FE-SEM images revealed that CNTs were reasonably dispersed in the alumina matrix. The porous membranes were evaluated for their water flux transport as well as their capacity to adsorb heavy metals ions. Selected membranes were able to remove about 97% cadmium from contaminated water. Further work is underway to enhance the removal efficiency of the developed membranes as well as to remove other heavy metals such as arsenic and mercury.

Keywords: heavy metal removal, inorganic membrane, nanocomposite, spark plasma sintering

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Authors: Kamil Dydek, Szymon Demski, Kamil Majchrowicz, Paulina Kozera, Bogna Sztorch, Dariusz Brząkalski, Zuzanna Krawczyk, Robert Przekop, Anna Boczkowska

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Carbon fibre reinforced polymers (CFRPs) are characterized by very high strength and stiffness in relation to their weight. In addition, properties such as corrosion resistance and low thermal expansion allow them to replace traditional materials, i.e., wood or metals, in many industries such as aerospace, automotive, marine, and sports goods. However, CFRPs, have some disadvantages -they have relatively low electrical conductivity and break brittle, which significantly limits their application possibilities. Moreover, conventional CFRPs are usually manufactured based on thermosets, which makes them difficult to recycle. The solution to these drawbacks is the use of the innovative thermoplastic resin (ELIUM from ARKEMA) as a matrix of composites and the modification by introducing into their structure thermoplastic nonwovens based on PET-G with the addition of multi-wall carbon nanotubes (MWCNTs). The acrylic-carbon composites, which were produced by the infusion technique, were tested for mechanical, thermo-mechanical, and electrical properties, and the effect of modifications on their microstructure was studied. Acknowledgment: This study was carried out with funding from grant no. LIDER/46/0185/L-11/19/NCBR/2020, financed by The National Centre for Research and Development.

Keywords: CFRP, MWCNT, ELIUM, electrical properties, infusion

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Authors: Sarbjit Singh

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This framework development explored the status of GSCM in manufacturing SMEs and concluded that there was a significant gap w.r.t carbon emissions measurement in the supply chain activities. The measurement of carbon emissions within supply chains is important green initiative toward its reduction. The majority of the SMEs were facing the problem to quantify the green house gas emissions in its supply chain & to make it a low carbon supply chain or GSCM. Thus, the carbon management initiatives were amalgamated with the supply chain activities in order to measure and reduce the carbon emissions, confirming the GHG protocol scopes. Henceforth, it covers the development of carbon management software (CMS) tool to quantify carbon emissions for effective carbon management. This tool is cheap and easy to use for the industries for the management of their carbon emissions within the supply chain.

Keywords: w.r.t carbon emissions, carbon management software, supply chain management, Indian Industry

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Authors: Krishna Prasad Maity, Narendra Tanty, Ananya Patra, V. Prasad

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Carbon nanotube (CNT) is a well-known material for very good electrical, thermal conductivity and high tensile strength. Because of that, it’s widely used in many fields like nanotechnology, electronics, optics, etc. In last two decades, polyaniline (PANI) with CNT and functionalized CNT (fCNT) have been promising materials in application of gas sensing, electromagnetic shielding, electrode of capacitor etc. So, the study of electrical conductivity of PANI/CNT and PANI/fCNT is important to understand the charge transport and interaction between PANI and CNT in the composite. It is observed that a transition in magnetoresistance (MR) with lowering temperature, increasing magnetic field and decreasing CNT percentage in CNT/PANI composite. Functionalization of CNT prevent the nanotube aggregation, improves interfacial interaction, dispersion and stabilized in polymer matrix. However, it shortens the length, breaks C-C sp² bonds and enhances the disorder creating defects on the side walls. We have studied electrical resistivity and MR in PANI with CNT and fCNT composites for different weight percentages down to the temperature 4.2K and up to magnetic field 5T. Resistivity increases significantly in composite at low temperature due to functionalization of CNT compared to only CNT. Interestingly a transition from negative to positive magnetoresistance has been observed when the filler is changed from pure CNT to functionalized CNT after a certain percentage (10wt%) as the effect of more disorder in fCNT/PANI composite. The transition of MR has been explained on the basis of polaron-bipolaron model. The long-range Coulomb interaction between two polarons screened by disorder in the composite of fCNT/PANI, increases the effective on-site Coulomb repulsion energy to form bipolaron which leads to change the sign of MR from negative to positive.

Keywords: coulomb interaction, magnetoresistance transition, polyaniline composite, polaron-bipolaron

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Authors: Rashad Al Araj, Adil K. Tamimi

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Concrete, despite being one of the most produced materials in the world, still has weaknesses and drawbacks. Significant concern of the cementitious materials in structural applications is their quasi-brittle behavior, which causes the material to crack and lose its durability. One of the very recently proposed mitigations for this problem is the implementation of nanotechnology in the concrete mix by adding carbon nanotubes (CNTs) to it. CNTs can enhance the critical mechanical properties of concrete as a structural material. Thus, this paper demonstrates a state-of-the-art review of reinforcing concrete with CNTs, emphasizing on the structural performance. It also goes over the properties of CNTs alone, the present methods and costs associated with producing them, the possible special applications of concretes reinforced with CNTs, the key challenges and drawbacks that this new technology still encounters, and the most reliable practices and methodologies to produce CNT-reinforced concrete in the lab. This work has shown that the addition of CNTs to the concrete mix in percentages as low as 0.25% weight of cement could increase the flexural strength and toughness of concrete by more than 45% and 25%, respectively, and enhance other durability-related properties, given that an effective dispersion of CNTs in the cementitious mix is achieved. Since nano reinforcement for cementitious materials is a new technology, many challenges have to be tackled before it becomes practiced at the mass level.

Keywords: sustainability, carbon nano tube, microsilica, concrete

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Authors: Ryoma Tokonami, Teruya Goto, Tatsuhiro Takahashi,

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For enhancing the mechanical property ofcarbon fiber reinforced plastic (CFRP), the surface modification of carbon fiber (CF) by multi-walled carbon nanotube (MWCNT) has received considerable attention using direct MWCNT growth on CF with a catalysis, MWCNT electrophoresis, and layer-by-layer of MWCNT with reactive polymers, etc. Among above approaches, the layer-by-layer method is the simplest process, however, the amount of MWCNTs on CF is very little, resulting in the small amount of improvement of the mechanical property of the composite. The remaining amount of MWCNT on CF after melt mixing of CF (short fiber) with thermoplastic matrix polymer was not examined clearly in the former studies. The present research aims to propose an effective layer-by-layer chemical grafting of a highly reactive oxazoline polymer, which has not been used before, and MWCNTs onto CF using the highly reactivity of oxazoline and COOH on the surface of CF and MWCNTs.With layer-by-layer method, the first uniform chemically bonded mono molecular layer on carbon fiber was formed by chemical surface reaction of carbon fiber, a reactive oxazoline polymer solution between COOH of carbon fiber and oxazoline. The second chemically bonded uniform layer of MWCNTs on the first layer was prepared through the first layer coated carbon fiber in MWCNT dispersion solution by chemical reaction between oxazoline and COOH of MWCNTs. The quantitative analysis of MWCNTs on carbon fiber was performed, showing 0.44 wt.% of MWCNTs based on carbon fiber, which is much larger amount compared with the former studies in layer-by-layer method. In addition, MWCNTs were also observed uniform coating on carbon fiber by scanning electron micrograph (SEM). Carbon fiber composites were prepared by melting mixing using polystyrene (PS) as a thermoplastic matrix because of easy removal of PS by solvent for additional analysis, resulting the 20% of enhancement of tensile strength and modulus by tensile strength test. It was confirmed bySEM the layer-by-layer structure on carbon fibers were remained after the melt mixing by removing PS with a solvent. As a conclusion, the effectiveness for the enhancement of the mechanical properties of CF(short fiber)/PS composite using the highly reactive oxazoline polymer for the first layer and MWCNT for the second layer, which act as the physical anchor, was demonstrated.

Keywords: interface, layer-by-layer, multi walled carbon nanotubes (MWCNTs), oxazoline

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Authors: Babak Safaei, A. M. Fattahi

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Polymer/carbon nanotube nanocomposites have a wide range of promising applications Due to their enhanced properties. In this work, free vibration analysis of single-walled carbon nanotube-reinforced composite plates is conducted in which carbon nanotubes are embedded in an amorphous polyethylene. The rule of mixture based on various types of plate model namely classical plate theory (CLPT), first-order shear deformation theory (FSDT), and higher-order shear deformation theory (HSDT) was employed to obtain fundamental frequencies of the nanocomposite plates. Generalized differential quadrature (GDQ) method was used to discretize the governing differential equations along with the simply supported and clamped boundary conditions. The material properties of the nanocomposite plates were evaluated using molecular dynamic (MD) simulation corresponding to both short-(10,10) SWCNT and long-(10,10) SWCNT composites. Then the results obtained directly from MD simulations were fitted with those calculated by the rule of mixture to extract appropriate values of carbon nanotube efficiency parameters accounting for the scale-dependent material properties. The selected numerical results are presented to address the influences of nanotube volume fraction and edge supports on the value of fundamental frequency of carbon nanotube-reinforced composite plates corresponding to both long- and short-nanotube composites.

Keywords: nanocomposites, molecular dynamics simulation, free vibration, generalized, differential quadrature (GDQ) method

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Authors: Mandeep Kaur, Jitendra K. Bera

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The search for atom-economical and green synthetic methods for the synthesis of functionalized molecules has attracted much attention. Metal ligand cooperation (MLC) plays a pivotal role in organometallic catalysis to activate C−H, H−H, O−H, N−H and B−H bonds through reversible bond breaking and bond making process. Towards this goal, a bifunctional N─heterocyclic carbene (NHC) based pyridyl-functionalized amide ligand precursor, and corresponding dearomatized iridium complex was synthesized. The NMR and UV/Vis acid titration study have been done to prove the proton response nature of the iridium complex. Further, the dearomatized iridium complex explored as a catalyst on the platform of MLC via dearomatzation/aromatization mode of action towards atom economical α and β─alkylation of ketones and secondary alcohols by using primary alcohols through hydrogen borrowing methodology. The key features of the catalysis are high turnover frequency (TOF) values, low catalyst loading, low base loading and no waste product. The greener syntheses of quinoline, lactone derivatives and selective alkylation of drug molecules like pregnenolone and testosterone were also achieved successfully. Another structurally similar iridium complex was also synthesized with modified ligand precursor where a pendant amide unit was absent. The inactivity of this analogue iridium complex towards catalysis authenticated the participation of proton responsive imido sidearm of the ligand to accelerate the catalytic reaction. The mechanistic investigation through control experiments, NMR and deuterated labeling study, authenticate the borrowing hydrogen strategy.

Keywords: C-C bond formation, hydrogen borrowing, metal ligand cooperation (MLC), n-heterocyclic carbene

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Authors: Z. Kolacinski, L. Szymanski. G. Raniszewski, D. Koza, L. Pietrzak

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Magnetic Bio-Nano-Fluid (BNF) can be composed of a buffer fluid such as plasma and magnetic nanoparticles such as iron, nickel, cobalt and their oxides. However iron is one of the best elements for magnetization by electromagnetic radiation. It can be used as a tool for medical diagnosis and treatment. Radio frequency (RF) radiation is able to heat iron nanoparticles due to magnetic hysteresis. Electromagnetic heating of iron nanoparticles and ferro-fluids BNF can be successfully used for non-invasive thermal ablation of cancer cells. Moreover iron atoms can be carried by carbon nanotubes (CNTs) if iron is used as catalyst for CNTs synthesis. Then CNTs became the iron containers and they screen the iron content against oxidation. We will present a method of CNTs addressing to the required cells. For thermal ablation of cancer cells we use radio frequencies for which the interaction with human body should be limited to minimum. Generally, the application of RF energy fields for medical treatment is justified by deep tissue penetration. The highly iron doped CNTs as the carriers creating magnetic fluid will be presented. An excessive catalyst injection method using electrical furnace and microwave plasma reactor will be presented. This way it is possible to grow the Fe filled CNTs on a moving surface in continuous synthesis process. This also allows producing uniform carpet of the Fe filled CNTs carriers. For the experimental work targeted to cell ablation we used RF generator to measure the increase in temperature for some samples like: solution of Fe2O3 in BNF which can be plasma-like buffer, solutions of pure iron of different concentrations in plasma-like buffer and in buffer used for a cell culture, solutions of carbon nanotubes (MWCNTs) of different concentrations in plasma-like buffer and in buffer used for a cell culture. Then the targeted therapies which can be effective if the carriers are able to distinguish the difference between cancerous and healthy cell’s physiology are considered. We have developed an approach based on ligand-receptor or antibody-antigen interactions for the case of colon cancer.

Keywords: cancer treatment, carbon nano tubes, drag delivery, hyperthermia, iron

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Authors: Illyas Md Isa, Mohamad Idris Saidin, Mustaffa Ahmad, Norhayati Hashim

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A highly selective and sensitive carbon paste electrode modified with multiwall carbon nanotubes and 2,6–diacetylpyridine-di-(1R)–(-)–fenchone diazine tetracarbonylmolybdenum(0) complex was used for determination of trace amounts of Cu(II) using square wave anodic stripping voltammetry (SWASV). The influences of experimental variables on the proposed electrode such as pH, supporting electrolyte, preconcentration potential and time, and square wave parameters were investigated. Under optimal conditions, the proposed electrode showed a linear relationship with concentration in the range of 1.0 × 10–10 to 1.0 × 10– 6 M Cu(II) with a limit of detection 8.0 × 10–11 M. The relative standard deviation (n = 5) for a solution containing 1.0 × 10– 6 M of Cu(II) was 0.036. The presence of various cations (in 10 and 100-folds concentration) did not interfere. Electrochemical impedance spectroscopy (EIS) showed that the charge transfer at the electrode-solution interface was favourable. The proposed electrode was applied for the determination of Cu(II) in several water samples. Results agreed very well with those obtained by inductively coupled plasma-optical emission spectrometry. The modified electrode was then proposed as an alternative for determination of Cu(II).

Keywords: chemically modified electrode, Cu(II), square wave anodic stripping voltammetry, tetracarbonylmolybdenum(0)

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Authors: Liu Zhiyuan, Sun Zongdi

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In this paper, the BP neural network model is established to predict the carbon trading price and carbon trading volume in Shanghai City. First of all, we find the data of carbon trading price and carbon trading volume in Shanghai City from September 30, 2015 to December 23, 2016. The carbon trading price and trading volume data were processed to get the average value of each 5, 10, 20, 30, and 60 carbon trading price and trading volume. Then, these data are used as input of BP neural network model. Finally, after the training of BP neural network, the prediction values of Shanghai carbon trading price and trading volume are obtained, and the model is tested.

Keywords: Carbon trading price, carbon trading volume, BP neural network model, Shanghai City

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Authors: Konstantinos G. Dassios, Guillaume Bonnefont, Gilbert Fantozzi, Theodore E. Matikas, Costas Galiotis

Abstract:

We report herein the development and preliminary mechanical characterization of fully-dense multi-wall carbon nanotube (MWCNT)-reinforced ceramics and glasses based on a completely new methodology termed High Shear Compaction (HSC). The tubes are introduced and bound to the matrix grains by aid of polymeric binders to form flexible green bodies which are sintered and densified by spark plasma sintering to unprecedentedly high densities of 100% of the pure-matrix value. The strategy was validated across a PyrexTM glass / MWCNT composite while no identifiable factors limit application to other types of matrices. Non-destructive evaluation, based on ultrasonics, of the dynamic mechanical properties of the materials including elastic, shear and bulk modulus as well as Poisson’s ratio showed optimum property improvement at 0.5 %wt tube loading while evidence of nanoscale-specific energy dissipative characteristics acting complementary to nanotube bridging and pull-out indicate a high potential in a wide range of reinforcing and multifunctional applications.

Keywords: ceramic matrix composites, carbon nanotubes, toughening, ultrasonics

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Authors: Rabindranath Jana, Biswajit Maity, Keka Rana

Abstract:

The most promising clean energy source is the fuel cell, since it does not generate toxic gases and other hazardous compounds. Again the direct methanol fuel cell (DMFC) is more user-friendly as it is easy to be miniaturized and suited as energy source for automobiles as well as domestic applications and portable devices. And unlike the hydrogen used for some fuel cells, methanol is a liquid that is easy to store and transport in conventional tanks. The most important part of a fuel cell is its membrane. Till now, an overall efficiency for a methanol fuel cell is reported to be about 20 ~ 25%. The lower efficiency of the cell may be due to the critical factors, e.g. slow reaction kinetics at the anode and methanol crossover. The oxidation of methanol is composed of a series of successive reactions creating formaldehyde and formic acid as intermediates that contribute to slow reaction rates and decreased cell voltage. Currently, the investigation of new anode catalysts to improve oxidation reaction rates is an active area of research as it applies to the methanol fuel cell. Surprisingly, there are very limited reports on nanostructured membranes, which are rather simple to manufacture with different tuneable compositions and are expected to allow only the proton permeation but not the methanol due to their molecular sizing effects and affinity to the membrane surface. We have developed a nanostructured fuel cell membrane from polydimethyl siloxane rubber (PDMS), ethylene methyl co-acrylate (EMA) and multi-walled carbon nanotubes (MWNTs). The effect of incorporating different proportions of f-MWNTs in polymer membrane has been studied. The introduction of f-MWNTs in polymer matrix modified the polymer structure, and therefore the properties of the device. The proton conductivity, measured by an AC impedance technique using open-frame and two-electrode cell and methanol permeability of the membranes was found to be dependent on the f-MWNTs loading. The proton conductivity of the membranes increases with increase in concentration of f-MWNTs concentration due to increased content of conductive materials. Measured methanol permeabilities at 60oC were found to be dependant on loading of f-MWNTs. The methanol permeability decreased from 1.5 x 10-6 cm²/s for pure film to 0.8 x 10-7 cm²/s for a membrane containing 0.5wt % f-MWNTs. This is due to increasing proportion of f-MWNTs, the matrix becomes more compact. From DSC melting curves it is clear that the polymer matrix with f-MWNTs is thermally stable. FT-IR studies show good interaction between EMA and f-MWNTs. XRD analysis shows good crystalline behavior of the prepared membranes. Significant cost savings can be achieved when using the blended films which contain less expensive polymers.

Keywords: fuel cell membrane, polydimethyl siloxane rubber, carbon nanotubes, proton conductivity, methanol permeability

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Authors: Surjyakanta Rana, Sreekantha B. Jonnalagadda

Abstract:

Synthesis of well distributed Pd nanoparticles (3 – 7 nm) on organo amine-functionalized graphene is reported, which demonstrated excellent catalytic activity towards Suzuki coupling reaction. The active material was characterized by X-ray diffraction (XRD), BET surface area, X-ray photoelectron spectra (XPS), Fourier-transfer infrared spectroscopy (FTIR), Raman spectra, Scanning electron microscope (SEM), Transmittance electron microscopy (TEM) analysis and HRTEM. FT-IR revealed that the organic amine functional group was successfully grafted onto the graphene oxide surface. The formation of palladium nanoparticles was confirmed by XPS, TEM and HRTEM techniques. The catalytic activity in the coupling reaction was superb with 100% conversion and 98 % yield and also activity remained almost unaltered up to six cycles. Typically, an extremely high turnover frequency of 185,078 h-1 is observed in the C-C Suzuki coupling reaction using organo di-amine functionalized graphene as catalyst.

Keywords: Di-amine, graphene, Pd nanoparticle, suzuki coupling

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Authors: Debananda Mohapatra, Subramanya Badrayyana, Smrutiranjan Parida

Abstract:

Recognizing the upcoming era of carbon nanostructures and their revolutionary applications, we investigated the formation and supercapacitor application of highly pure and hydrophilic carbon nano-onions (CNOs) by economical one-step flame-synthesis procedure. The facile and scalable method uses easily available organic carbon source such as clarified butter, restricting the use of any catalyst, sophisticated instrumentation, high vacuum and post processing purification procedure. The active material was conformally coated onto a locally available cotton wipe by “sonicating and drying” process to obtain novel, lightweight, inexpensive, flexible, binder-free electrodes with strong adhesion between nanoparticles and porous wipe. This interesting electrode with CNO as the active material delivers a specific capacitance of 102.16 F/g, the energy density of 14.18 Wh/kg and power density of 2448 W/kg which are the highest values reported so far in symmetrical two electrode cell configuration with 1M Na2SO4 as an electrolyte. Incorporation of CuO nanoparticles to these functionalized CNOs by one-step hydrothermal method add up to a significant specific capacitance of 420 F/g with deliverable energy and power density at 58.33 Wh/kg and 4228 W/kg, respectively. The free standing CNOs, as well as CNO-CuO composite electrode, showed an excellent cyclic performance and stability retaining 95 and 90% initial capacitance even after 5000 charge-discharge cycles at a current density of 5 A/g. This work presents a new platform for high performance supercapacitors for next generation wearable electronic devices.

Keywords: binder-free, flame synthesis, flexible, carbon nano-onion

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Authors: W. Rashmi, M. Khalid, O. Seiksan, R. Saidur, A. F. Ismail

Abstract:

Nanofluids have received much more attention since its discovery. They are believed to be promising coolants in heat transfer applications due to their enhanced thermal conductivity and heat transfer characteristics. In this study, the enhancement in heat transfer of CNT-nanofluids under turbulent flow conditions is investigated experimentally. Carbon nanotube (CNTs) concentration was varied between 0.051-0.085 wt%. The nanofluid suspension was stabilized by gum arabic (GA) through a process of homogenisation and sonication. The flow rates of cold fluid (water) is varied from 1.7-3 L/min and flow rates of the hot fluid is varied between 2-3.5 L/min. Thermal conductivity, density and viscosity of the nanofluids were also measured as a function of temperature and CNT concentration. The experimental results are validated with theoretical correlations for turbulent flow available in the literature. Results showed an enhancement in heat transfer range between 9-67% as a function of temperature and CNT concentration.

Keywords: nanofluids, carbon nanotubes (CNT), heat transfer enhancement, heat transfer

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Authors: Young Nam Chun, Mun Sup Lim

Abstract:

Carbon dioxide and methane, the major components of biomass pyrolysis/gasification gas and biogas, top the list of substances that cause climate change, but they are also among the most important renewable energy sources in modern society. The purpose of this study is to convert carbon dioxide and methane into high-quality energy using char and commercial activated carbon obtained from biomass pyrolysis as a microwave receptor. The methane reforming process produces hydrogen and carbon. This carbon is deposited in the pores of the microwave receptor and lowers catalytic activity, thereby reducing the methane conversion rate. The deposited carbon was removed by carbon gasification due to the supply of carbon dioxide, which solved the problem of microwave receptor inactivity. In particular, the conversion rate remained stable at over 90% when the ratio of carbon dioxide to methane was 1:1. When the reforming results of carbon dioxide and methane were compared after fabricating nickel and iron catalysts using commercial activated carbon as a carrier, the conversion rate was higher in the iron catalyst than in the nickel catalyst and when no catalyst was used. 

Keywords: microwave, gas reforming, greenhouse gas, microwave receptor, catalyst

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Authors: Adel Elomri

Abstract:

The notion of carbon footprinting is ever more widespread as companies are becoming increasingly aware that tackling carbon emissions and being seen to do so is a key issue to face governments, customers and other stakeholders’ pressures towards delivering environmentally friendly services and activities. In this contest, many firms are taking self-initiatives to reduce their own carbon emissions while some other are constrained to obey to different regulations/policies (e.g. carbon tax or carbon Cap) designed by higher authorities targeting a low-carbon environment. Using buyer-vendor framework, this paper provides some insights on how effective are these self-initiatives and regulatory policies when only concerning firms at the individual level and not the whole supply chain they are part of. We show that when firms individually engage in reducing their direct carbon emissions either under self-initiatives or regulatory policy, an opposite expected outcome resulting in a higher global supply chain emission can occur. This effect is referred to as the carbon seesaw effect. Moreover, we show that coordinating or centralizing the supply chain -contrary to what one may think at first- is not often the appropriate solution to get rid of this effect.

Keywords: carbon emissions, supply chain coordination, EOQ, sustainable operations

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Authors: K. Mondal, S. Talapatra, M. Terrones, S. Pokhrel, C. Frizzel, B. Sumpter, V. Meunier, A. L. Elias

Abstract:

Worldwide energy independence is reliant on the ability to leverage locally available resources for fuel production. Recently, syngas produced through gasification of carbonaceous materials provided a gateway to a host of processes for the production of various chemicals including transportation fuels. The basis of the production of gasoline and diesel-like fuels is the Fischer Tropsch Synthesis (FTS) process: A catalyzed chemical reaction that converts a mixture of carbon monoxide (CO) and hydrogen (H₂) into long chain hydrocarbons. Until now, it has been argued that only transition metal catalysts (usually Co or Fe) are active toward the CO hydrogenation and subsequent chain growth in the presence of hydrogen. In this paper, we demonstrate that carbon nanotube (CNT) surfaces are also capable of hydro-deoxygenating CO and producing long chain hydrocarbons similar to that obtained through the FTS but with orders of magnitude higher conversion efficiencies than the present state-of-the-art FTS catalysts. We have used advanced experimental tools such as XPS and microscopy techniques to characterize CNTs and identify C-O functional groups as the active sites for the enhanced catalytic activity. Furthermore, we have conducted quantum Density Functional Theory (DFT) calculations to confirm that C-O groups (inherent on CNT surfaces) could indeed be catalytically active towards reduction of CO with H₂, and capable of sustaining chain growth. The DFT calculations have shown that the kinetically and thermodynamically feasible route for CO insertion and hydro-deoxygenation are different from that on transition metal catalysts. Experiments on a continuous flow tubular reactor with various nearly metal-free CNTs have been carried out and the products have been analyzed. CNTs functionalized by various methods were evaluated under different conditions. Reactor tests revealed that the hydrogen pre-treatment reduced the activity of the catalysts to negligible levels. Without the pretreatment, the activity for CO conversion as found to be 7 µmol CO/g CNT/s. The O-functionalized samples showed very activities greater than 85 µmol CO/g CNT/s with nearly 100% conversion. Analyses show that CO hydro-deoxygenation occurred at the C-O/O-H functional groups. It was found that while the products were similar to FT products, differences in selectivities were observed which, in turn, was a result of a different catalytic mechanism. These findings now open a new paradigm for CNT-based hydrogenation catalysts and constitute a defining point for obtaining clean, earth abundant, alternative fuels through the use of efficient and renewable catalyst.

Keywords: CNT, CO Hydrodeoxygenation, DFT, liquid fuels, XPS, XTL

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